Principles of Geology, by Charles Lyell

Re: Principles of Geology, by Charles Lyell

Postby admin » Fri Jul 17, 2015 3:02 am

CHAPTER 23

Secondary formations – Brief enumeration of the principal groups – No species common to the secondary and tertiary rocks – Chasm between the Eocene and Maestricht beds – Duration of secondary periods – Former continents placed where it is now sea – Secondary fresh-water deposits why rare – Persistency of mineral composition why apparently greatest in older rocks – Supposed universality of red marl formations – Secondary rocks why more consolidated – Why more fractured and disturbed – Secondary volcanic rocks of many different ages

SECONDARY FORMATIONS.

As we have already exceeded the limits originally assigned to this work, it is not our intention to enter, at present, upon a detailed description of the formations usually called 'Secondary,' the elucidation of which might well occupy another volume. By 'secondary,' we mean those stratified rocks older than the tertiary, which contain distinct organic remains, and which sometimes pass into the strata called 'Primary,' to be described in our concluding chapters.

The observations which we are about to offer have chiefly for their object to show that the rules of interpretation adopted by us for the tertiary formations, are equally applicable to the phenomena of the secondary series. This last has been divided into several groups, and we shall briefly enumerate some of the principal of these for the convenience of reference, without pretending to offer to the student a systematic classification, founded on a full comparison of fossil remains.

PRINCIPAL SECONDARY GROUPS. (Descending Series.)

1. Strata from the chalk of Maestricht to the lower green-sand inclusive.

The number of species of testacea already procured from the different members of this division amount to about 1000. The principal subdivisions are the Maestricht beds, the chalk with and without flints, the upper green-sand, the gault, and the lower green-sand. The first of these groups is seen at St. Peter's Mount, Maestricht, reposing upon the upper flinty chalk of England and France. It is characterized by a peculiar assemblage of organic remains, perfectly distinct from those of the tertiary period. M. Deshayes, after a careful comparison, and after making drawings of more than 200 species of the Maestricht shells, has been unable to identify anyone of them with the numerous tertiary fossils in his collection. On the other hand, there are several shells which are decidedly common to the calcareous beds of Maestricht and the white chalk. The names of twelve of these, communicated by M. Deshayes, will be found in Appendix II., p. 60.

But the fossils of the Maestricht beds extend not merely into the white chalk of the French geologists, but into their 'green-sand,' which appears to correspond very nearly with the upper green-sand of the English geologists. A list of five species of shells, common to the Maestricht beds and the upper green-sand of France, will be found in Appendix II., p. 60.

It will be seen by the above lists, that the belemnite, one of the cephalopodes not found in any tertiary formation, occurs in the Maestricht beds; an ammonite has also been discovered in this group by Dr. Fitton, and is now in the collection of the Geological Society of London.

That gigantic species of reptile, the Mososaurus of Maestricht, has also been found by Mr. Mantell in the English chalk.

2. The Wealden, or the strata from the Weald clay to the Purbeck limestone inclusive.

The numerous fossil-shells of this group are referrible to freshwater genera, which are associated with many remains of fluviatile and terrestrial reptiles and land-plants. We believe that no species, whether animal or vegetable, in this group, has been distinctly identified with any found either in the superincumbent marine beds of the first division, or in the subjacent rocks of the group No. 3, which are also of marine origin.

3. Oolite, or Jura limestone formation.

This division, in which we do not include the lias, contains a great number of subordinate members, several of which may relate, perhaps, to periods as important as our subdivisions of the great tertiary epoch. The shells, even of the uppermost part of the series, appear to differ entirely from the species found in the division No. 1.

4. The Lias.

The shells of the argillaceous limestone, termed lias, and other associated strata, differ considerably from those of the preceding group, as do the greater number of species of vertebrated animals.

5. Strata intervening between the Lias and the Carboniferous group.

The formations which are referrible to the interval which separated the great coal formations from the division last mentioned, are very various, and some of them, like the new red sandstone, contain few organic remains. One group, however, belonging to this period, the Muschelkalk of the Germans, which has no precise equivalent among the English strata, contains many organic remains belonging to species perfectly distinct from the fossils of the lias, and equally so from those of the carboniferous era next to be mentioned.

6. Carboniferous group, comprising the coal-measures, the mountain limestone, the old red sandstone, the transition limestone, the coarse slates and slaty sandstones called graywacke by some writers, and other associated rocks.

The mountain and transition limestones of the English geologists contain many of the same species of shells in common, and we shall therefore refer them for the present to the same great period; and, consequently, the coal, which alternates in some districts with mountain limestone, and the old red sandstone which intervenes between the mountain and transition limestones, will be considered as belonging to the same period. The coal-bearing strata are characterized by several hundred species of plants, which serve very distinctly to mark the vegetation of part of this era. Some of the rocks, termed graywacke in Germany, are connected by their fossils with the mountain limestone.

With this group we shall conclude our enumeration for the present; for although other divisions may hereafter be requisite, we are not aware that any antecedent periods can yet be established on the evidence of a distinct assemblage of fossil remains. Traces of organization undoubtedly occur in rocks more ancient than the transition limestone, and its associated sandstones, called graywacke; but we cannot refer them to a distinct geological period, according to the principles laid down in this work, until we have obtained data for determining the specific characters of a considerable number of fossil remains.

In reviewing the above groups we may first call the reader's attention to the important fact stated on the authority of M. Deshayes, that no species of fossil shells has yet been found common to the secondary and tertiary formations. [1] This marked discordance in the organic remains of the two series is not confined to the testacea, but extends, so far as a careful comparison has yet been instituted, to all the other departments of the animal kingdom, and to the fossil plants. I am informed by M. Agassiz, whose great work on fossil fish is anxiously looked for by geologists, that after examining about 500 species of that class, in formations of all ages, he could discover no one common to the secondary and tertiary rocks; nay, all the secondary species hitherto known to him, belong to genera distinct from those established for the classification of tertiary and recent fish.

Chasm between the Eocene and Maestricht formations. -- There appears, then, to be a greater chasm between the organic remains of the Eocene and Maestricht beds, than between the Eocene and Recent strata; for there are some living shells in the Eocene formations, while there are no Eocene fossils in the newest secondary group. It is not improbable that a greater interval of time may be indicated by this greater dissimilarity in fossil remains. In the 3rd and 4th chapters we endeavoured to point out that we have no right to expect, even when we have investigated a greater extent of the earth's surface, that we shall be able to bring to light an unbroken chronological series of monuments from the remotest eras to the present; but as we have already discovered a long succession of deposits of different ages, between the tertiary groups first known and the recent formations, so we may, perhaps, hereafter detect an equal, or even greater series, intermediate between the Maestricht beds and the Eocene strata.

Duration of secondary periods. -- The different subdivisions of the secondary group No.1, extending from the chalk of Maestricht to the lower green-sand inclusive, may, perhaps, relate to a lapse of ages as immense as the united tertiary periods, of which we have sketched the eventful history in this volume. Such a conjecture, at least, seems warranted, if we can form any estimate of the quantity of time, by comparing the amount of vicissitude in animal life which has occurred during its lapse.

Position of former continents. -- The existence of sea as well as land, at every geological period, is attested by the remains of terrestrial plants imbedded in the deposits of all ages, even the most remote. We find fluviatile shells not unfrequently in the secondary strata, and here and there some fresh-water formations; but the latter are less common than in the tertiary series. For this fact we have prepared the reader's mind, by the views advanced in the third chapter respecting the different circumstances under which we conceive the secondary and tertiary strata to have originated. We have there hinted, that the former may have been accumulated in an ocean like the Pacific, where coralline and shelly limestone are forming, or in a basin like the bed of the western Atlantic, which may have received for ages the turbid waters of great rivers, such as the Amazon, and Orinoco, each draining a considerable extent of continent. The tertiary deposits, on the other hand, may have been accumulated during the growth of a continent, by the successive emergence of new lands, and the uniting together of islands. During such changes, inland seas and lakes would be caused, and afterwards filled up with sediment, and then raised above the level of the waters.

That the greater part of the space now occupied by the European continent was sea when some of the secondary rocks were produced, must be inferred from the wide areas over which several of the marine groups are diffused; but we do not suppose that the quantity of land was less in those remote ages, but merely that its position was very different. In the above tabular view of the secondary rocks, we have shown that immediately below the division No. 1, or 'the chalk and green-sand,' is placed a fresh-water formation called, in the south-east of England, the Wealden. This group has been ascertained to extend from west to east (from Lulworth Cove to the boundary of the Lower Boulonnois) about 200 English miles, and from north-west to south-east (from Whitchurch to Beauvais), about 220 miles, the depth or total thickness of the beds, where greatest, being about 2000 feet. [2]

Now these phenomena most clearly indicate, that there was a constant supply in this region, for a long period, of a considerable body of fresh water, such as might be supposed to have drained a continent, or a large island, containing within it a lofty chain of mountains. Dr. Fitton, in speaking of these appearances, recalls to our recollection that the delta of the newly-discovered Quorra, or Niger, in Africa, stretches into the interior for more than 170 miles, and occupies, it is supposed, a space of more than 300 miles along the coast, thus forming a surface of more than 25,000 square miles" or equal to about one half of England. [3]

Now if this modern 'delta,' or, in other words, that part of the bed of the Atlantic which has been converted into land by matter deposited immediately at the river's mouth, be so extensive, how much larger may be the space over which the same kind of sediment may be distributed by the action of the tides and currents! If, then, groups like the Wealden may be formed near the mouths of great rivers, others, like the lias, may be produced by the wider dispersion of similar materials over larger submarine areas. For we may conceive that the Niger may carry out the remains of land plants" and the carcasses and bones of fluviatile reptiles, into places where they may be swept away by currents and afterwards mingled far and wide with the marine shells and corals of the Atlantic.

The reader will remember that we stated, in the first volume, [4] that the common crocodile of the Ganges frequents both fresh and salt water, the same species being sometimes seen far inland, many hundred miles from the sea, and at the same time swarming on the sand- banks in the salt and brackish water beyond the limits of the delta.

If we are asked where the continent was placed from the ruins of which the Wealden strata were derived, we are almost tempted to speculate on the former existence of the Atlantis of Plato, which may be true in geology, although fabulous as an historical event. We know that the present European lands have come into existence almost entirely since the deposition of the chalk, and the same period may have sufficed for the disappearance of a continent of equal magnitude, situated farther to the west.

Secondary fresh-water deposits why rare. -- If there were extensive tracts of land in the secondary period, we may presume that there were lakes also; yet we are not aware of any pure lacustrine formations interstratified with rocks older than the chalk. Perhaps their absence may be accounted for by the adoption of the theoretical views above set forth; for if the present ocean coincides for the most part with the site of the ancient continent, the places occupied by lakes must have been submerged. It should also be recollected, that the area covered by lakes, at anyone time, is very insignificant in proportion to the sea, and, therefore, we may expect that, after the earth's surface has undergone considerable revolutions in its physical geography, the lacustrine strata will be concealed, for the most part, under superimposed marine deposits.

Persistency of mineral character. -- In the same manner as it is rare and difficult to find ancient lacustrine strata, so also we can scarcely expect to discover newer marine groups preserving the same lithological characters continuously throughout wide areas. The chalk now seen stretching for thousands of miles over different parts of Europe, has become visible to us by the effect, not of one, but of many distinct series of movements. Time has been required, and a succession of geological periods, to raise it above the waves in so many regions; and if calcareous rocks of the Eocene or Miocene periods have been formed, preserving an homogeneous mineral composition throughout equally extensive regions, it may require convulsions as numerous as all those which have occurred since the origin of the chalk, to bring them up within the sphere of human observation. Hence the rocks of more modern periods may appear of partial extent, as compared to those of remoter eras, not because there was any original difference of circumstances throughout the globe when they were formed, but because there has not been sufficient time for the development of a great series of subterranean volcanic operations since their origin.

At the same time, the reader should be warned not to place implicit reliance on the alleged persistency of the same mineral characters in secondary rocks. [5] When it was first ascertained that an order of succession could be traced in the principal groups of strata above enumerated by us, names were given to each, derived from the mineral composition of the rocks in those parts of Germany, England or France, where they happened to be first studied. When it was afterwards acknowledged that the zoological and phytological characters of the same formations were far more persistent than their mineral peculiarities, the old names were still retained, instead of being exchanged for others founded on more constant and essential characters. The student was given to understand, that the terms chalk, green-sand, oolite, red marl, coal, and others, were to be taken in a liberal and extended sense; that chalk was not always a cretaceous rock, but, in some places, as on the northern flanks of the Pyrenees, and in Catalonia, a saliferous red marl. Green-sand, it was said, was rarely green, and frequently not arenaceous, but represented in parts of the south of Europe by a hard dolomitic limestone. In like manner, it was declared that the oolitic texture was rather an exception to the general rule in rocks of the oolitic period, and that no particle of carbonaceous matter could often be detected in the true coal formation of many districts where it attains great thickness. It must be obvious to everyone, that inconvenience and erroneous prepossessions could hardly fail to arise from such a nomenclature, and accordingly a fallacious mode of reasoning has been widely propagated, chiefly by the influence of a language so singularly inappropriate.

After the admission that the identity or discordance of mineral character was by no means a sure test of agreement or disagreement in the age of rocks, it was still thought, by many geologists, that if they found a rock at the antipodes agreeing precisely in mineral composition with another well known in Europe, they could fairly presume that both are of the same age, until the contrary could be shown.

Now it is usually difficult or impossible to combat such an assumption, on geological grounds, so long as we are imperfectly acquainted with the geology of a distant country, inasmuch as there are often no organic remains in the foreign stratum, and even if these abound and are specifically different from the fossils of the supposed European equivalent, it may be objected, that we cannot expect the same species to have inhabited very distant quarters of the globe at the same time.

Supposed universality of red marl. -- We shall select a remarkable example of the erroneous mode of generalizing now alluded to. A group of red marl and sandstone, sometimes containing salt and gypsum, is found in England interposed between the lias and the carboniferous strata. For this reason, other red marls and sandstones, associated some of them with salt and others with gypsum, and occurring not only in different parts of Europe, but in Peru, India, the salt deserts of Asia, those of Africa, in a word, in every quarter of the globe, have been referred to one and the same period. The burden of proof is not supposed to rest with those who insist on the identity of age of all these groups, so that it is in vain to urge as an objection, the improbability of the hypothesis which would imply that all the moving waters on the globe were once simultaneously charged with sediment of a red colour.

But the absurdity of pretending to identify, in age, all the red sandstones and marls in question, has at length been sufficiently exposed, by the discovery that, even in Europe, they belong decidedly to many different epochs. We have already ascertained, that the red sandstone and red marl with which the rock-salt of Cardona is associated, may be referred to the period of our chalk and green-sand. [6] We have pointed out that in Auvergne there are red marls and variegated sandstones, which are undistinguishable in mineral composition, from the new red sandstone of English geologists, but which were deposited in the Eocene period; and, lastly, the gypseous red marl of Aix in Provence, formerly supposed to be a marine secondary group, is now acknowledged to be a tertiary freshwater formation.

Secondary rocks why more consolidated. -- One of the points where the analogy between the secondary and tertiary formations has been supposed to fail is the greater degree of solidity observable in the former. Undoubtedly the older rocks, in general, are more stony than the newer; and most of the tertiary strata are more loose and incoherent in their texture than the secondary. Many exceptions, however, may be pointed out, especially in those calcareous and siliceous deposits which have been precipitated in great part from the waters of mineral springs, and have been originally compact. Of this description are a large proportion of the Parisian Eocene rocks, which are more stony than most of the English secondary groups.

But a great number of strata have evidently been consolidated subsequently to their deposition by a slow lapidifying process. Thus loose sand and gravel are bound together by waters holding carbonate and oxide of iron, carbonate of lime, silica, and other ingredients, in solution. These waters percolate slowly the earth's crust in different regions, and often remove gradually the component elements of fossil organic bodies, substituting other substances in their place. It seems, moreover, that the draining off of the waters during the elevation of land may often cause the setting of particular mixtures, in the same manner as mortar hardens when desiccated, or as the recent soft marl of Lake Superior becomes highly indurated when exposed to the air. [7] The conversion of clay into shale, and of sand into sandstone, may, in many cases, be attributed to simple pressure, produced by the weight of superincumbent strata, or by the upward heaving of subjacent masses during earthquakes. Heat is another cause of a more compact and crystalline texture, which will be considered when we speak of the strata termed 'primary.' All the changes produced by these various means require time for their completion; and this may explain, in a satisfactory manner, why the older rocks are most consolidated, without entitling us to resort to any hypothesis respecting an original distinctness in the degree of lapidification of the secondary strata.

Secondary rocks why more disturbed. -- As the older formations are generally more stony, so also they are more fractured, curved, elevated, and displaced, than the newer. Are we, then to infer, with some geologists, that the disturbing forces were more energetic in remoter ages? No conclusion can be more unsound; for as the moving power acts from below, the newer strata cannot be deranged without the subjacent rocks participating in the movement j while we have evidence that the older have been frequently shattered, raised, and depressed, again and again, before the newer rocks were formed. It is evident that if the disturbing power of the subterranean causes be exerted with uniform intensity in each succeeding period, the quantity of convulsion undergone by different groups of strata will generally be great in proportion to their antiquity. But exceptions will occur, owing to the partial operation of the volcanic forces at particular periods, so that we sometimes find tertiary strata more elevated and disturbed, in particular countries, than are the secondary rocks in others.

Some of the enormous faults and complicated dislocations of the ancient strata may probably have arisen from the continued repetition of earthquakes in the same place, and sometimes from two distinct series of convulsions, which have forced the same masses in different, and even opposite directions, sometimes by vertical, at others by horizontal movements.

Secondary volcanic rocks of different ages. -- The association of volcanic rocks with different secondary strata is such as to prove, that there were igneous eruptions at many distinct periods, as also that they were confined during each epoch, as now, to limited areas. Thus, for example, igneous rocks contemporaneous with the carboniferous strata abound in some countries, but are wanting in others. So it is evident that the bottom of the sea, on which the oolite and its contemporary deposits were thrown down, was, for the most part, free from submarine eruptions; but at some points, as in the Hebrides, it seems that the same ocean was the theatre of volcanic action. We have mentioned in the first volume, [8] that as the ancient eruptions occurred in succession, sufficient time usually intervening between them to allow of the accumulation of many subaqueous strata, so also should we infer that subterranean movements, which are another portion of the volcanic phenomena, occurred separately and in succession.

_______________

Notes:

1. M. Deshayes assures me that he has seen no tertiary shells in the Gosau beds, supposed by some geologists to be intermediate between the secondary and tertiary formations; but that some of the most characteristic species of Gosau occur in the green-sand beneath the chalk, at Mons in Belgium.

2. Fitton's Geology of Hastings, p. 58.

3. Fitton's Geology of Hastings, p. 58, who cites Lander's Travels.

4. Page 243; Second Edition, p. 279.

5. See some remarks on this subject, vol. i. p. 90, and Second Edition, p. 102.

6. I was led to this opinion when I visited Cardona in 1830, and before I was aware that M. Dufrenoy had arrived at the same conclusions. Ann. des Sci. Nat., Avril, 1831, p.449.

7. Vol. i. p. 226, and Second Edition, p.259.

8. Chap. v. p. 88; and Second Edition, p. 100.
admin
Site Admin
 
Posts: 28480
Joined: Thu Aug 01, 2013 5:21 am

Re: Principles of Geology, by Charles Lyell

Postby admin » Fri Jul 17, 2015 3:03 am

CHAPTER 24

On the relative antiquity of different mountain-chains – Theory of M. Elie de Beaumont – His opinions controverted – His method of proving that different chains were raised at distinct periods – His proof that others were contemporaneous – His reasoning why not conclusive – His doctrine of the parallelism of contemporaneous lines of elevation – Objections – Theory of parallelism at variance with geological phenomena as exhibited in Great Britain – Objections of Mr. Conybeare – How far anticlinal lines formed at the same period are parallel – Difficulties in the way of determining the relative age of mountains

RELATIVE ANTIQUITY OF MOUNTAIN-CHAINS.

THAT the different parts of our continents have been elevated, in succession, to their present height above the level of the sea, is an opinion which has been gradually gaining ground with the progress of science; but no one before M. Elie de Beaumont had the merit even of attempting to collect together the recorded facts which bear on this subject, and to reduce them to one systematic whole. The above-mentioned geologist was eminently qualified for the task, as one who had laboured industriously in the field of original observation, and who combined a considerable knowledge of facts with an ardent love of generalization.

But he has been ambitious, we think unfortunately, of anticipating the march of discovery in reference to the comparative antiquity of different mountain-chains and their supposed connexion with changes in the animate world. His speculations differ entirely from the conclusions to which we have arrived, and we therefore think it necessary to explain fully the reasons of our dissent. In order to put the reader in possession of the principal points of M. de Beaumont's theory, we shall first offer a brief sketch of them, and then proceed to analyze the data on which they are founded.

Theory of M. Elie de Beaumont.

1st. He supposes 'that in the history of the earth there have been long periods of comparative repose, during which the deposition of sedimentary matter has gone on in regular continuity, and there have also been short periods of paroxysmal violence during which that continuity was broken.

'2ndly. At each of these periods of violence or "revolution" in the state of the earth's surface, a great number of mountain-chains have been formed suddenly.

'3rdly. All the chains thrown up by a particular revolution have one uniform direction, being parallel to each other within a few degrees of the compass, even when situated in remote regions; but the chains thrown up at different periods have, for the most part, different directions.

'4thly. Each "revolution," or, as it is sometimes termed, "frightful convulsion," has coincided in date with another geological phenomenon, namely, "the passage from one independent sedimentary formation to another," characterized by a considerable difference in "organic types."

'5thly. There has been a recurrence of these paroxysmal movements from the remotest geological periods, and they may still be reproduced, and the repose in which we live may hereafter be broken by the sudden upthrow of another system of parallel chains of mountains.

'6thly. We may presume that one of these revolutions has occurred within the historical era when the Andes were upheaved to their present height, for that chain is the best defined and least obliterated feature observable in the present exterior configuration of the globe, and was probably the last elevated.

'7thly. The instantaneous upheaving of great mountain masses must cause a violent agitation in the waters of the sea, and the rise of the Andes may, perhaps, have produced that transient deluge which is noticed among the traditions of so many nations.

'Lastly. The successive revolutions above mentioned cannot be referred to ordinary volcanic forces, but may depend on the secular refrigeration of the heated interior of our planet.' [1]

It will at once be seen, that the greater number of the above propositions are directly opposed to that theory which we have endeavoured to deduce, partly from the study of the earth's structure, and partly from the analogy of changes now in progress in the animate and inanimate world.

Our opinions respecting the alternation of periods of general repose and disorder have been explained in former chapters; [2] and we have pointed out our objections to the hypothesis which substitutes paroxysmal violence for the reiterated recurrence of minor convulsions. [3]

The speculation of M. de Beaumont concerning the 'secular refrigeration' of the internal nucleus of the globe, considered as a cause of the instantaneous rise of mountain-chains, appears to us mysterious in the extreme, and not founded upon any induction from facts; whereas the intermittent action of subterranean volcanic heat is a known cause capable of giving rise to the elevation and subsidence of the earth's crust without interruption to the general repose of the habitable surface.

We have shown, in the second volume, that we believe the changes in physical geography, which are unceasingly in progress, to be among the causes which contribute, in the course of ages, to the extermination of certain species of animals and plants; but the influence of these causes is slow and, for the most part, indirect, and has no analogy with those sudden catastrophes which are introduced into the theory now under review. What have appeared to us to be the true causes of the abrupt transitions from one set of strata to another, containing distinct organic remains, have been explained at length in the third and fourth chapters of this volume. [4]

The notion of deluges accompanying the protrusion of mountain-chains is founded on a belief of the instantaneousness of the movement which we are prepared to controvert, and on other assumptions which we have discussed in a former part of this volume. [5] On these topics, therefore, it will be unnecessary for us to dilate at present, and we shall merely address ourselves to the analysis of that evidence whereby M. de Beaumont endeavours to establish the successive elevation of different mountain-chains, and the supposed law of parallelism in the lines of contemporaneous elevation.

M. de Beaumont's proofs that different chains were raised at different epochs. -- 'We observe,' says M. Elie de Beaumont, 'along nearly all mountain-chains, when we attentively examine them, that the most recent rocks extend horizontally up to the foot of such chains, as we should expect would be the case if they were deposited in seas or lakes of which these mountains have partly formed the shores; whilst the other sedimentary beds tilted up, and more or less contorted on the flanks of the mountains, rise in certain points even to their highest crests.' [6] There are, therefore, in each chain two classes of sedimentary rocks, the ancient or inclined beds, and the newer or horizontal. It is evident that the first appearance of the chain itself was an event 'intermediate between the period when the beds, now upraised, were deposited, and that when the strata were produced horizontally at its feet.'

Image
No. 82.

Thus the chain A received its present form after the deposition of the strata b, which have undergone great movements, and before the deposition of the group c, in which the strata have not suffered derangement.

If we then discover another chain, B, in which we find not only the formation b, but the group c also, disturbed and thrown on its edges, we may infer that the latter chain is of subsequent date to A; for B was elevated after the deposition of c, and before that of the group d; whereas A originated before the strata c were formed.

Image
No. 83.

In order to ascertain whether other mountain ranges are of contemporaneous date with A and B, or whether they are referrible to distinct periods, we have only to inquire whether the geological phenomena are identical, namely, whether the inclined and undisturbed sets of strata correspond to those in the types above mentioned.

Objections to M. de Beaumont's theory. -- Now all this reasoning is perfectly correct, so long as the particular groups of strata band c are not confounded with the geological periods to which they may belong, and provided due latitude is given to the term contemporaneous; for it should be understood to allude not to a moment of time, but to the interval, whether brief or protracted, which has elapsed between two events, namely, between the accumulation of the inclined and that of the horizontal strata.

But, unfortunately, the distinct import of the terms 'formation' and 'period' has been overlooked, or not attended to by M. de Beaumont, and hence the greater part of his proofs are equivocal, and his inferences uncertain; and even if no errors had arisen from this source, the length of some of his intervals is so immense, that to affirm that all the chains raised in such intervals were contemporaneous, is an abuse of language.

In order to illustrate our argument, let us select the Pyrenees as an example. This range of mountains, says M. de Beaumont, rose suddenly (a un seul jet) to its present elevation at a certain epoch in the earth's history, namely, between the deposition of the chalk and that of the tertiary formations; for the former are seen in vertical, curved, and distorted beds on the flanks of the chain, while the latter rest upon them in horizontal strata at its base.

The only proof offered of the extreme suddenness of the convulsion is the shortness of the time which intervened between the formation of the chalk and that of the tertiary strata. 'For it follows,' we are told, 'from the unconformable position of two systems of beds, the inclined and the horizontal. that the elevation of the former has not been effected in a continuous and progressive manner, but that it has been produced in a space of time comprised between the periods of deposition of the two consecutive rocks, and during which no regular series of beds was formed; in a word, that it was sudden and of short duration.' [7]

We are prepared to show that the Pyrenees cannot be assumed to have risen, as M. de Beaumont imagines, in the interval between the period of the chalk and that of the tertiary strata; for we can only say that the movement took place after the commencement of the chalk epoch, and before the close of the Miocene tertiary period. But, first. let us suppose the premises of our author to be correct, and let us permit him to exclude the whole period of the chalk, on one hand, and of the tertiary formations in contact with it on the other; what will then be the duration of the interval? We can only estimate its importance by ascertaining what description of chalk is found on the flanks of the Pyrenees, and what horizontal tertiary formations at their base.

Now the beds called chalk, although they differ widely in mineral composition from the white chalk with flints of England and France, contain the same species of fossil shells, and may, therefore, on that evidence, be referred to the same age. [8] On the other hand, the horizontal tertiary strata at the western end of the Pyrenees, near Bayonne, are certainly of the Miocene period.

Such, then, being the age of the strata, and granting even that the movement occurred after the period of the white chalk, and before the beginning of the Miocene era, there still remains ample scope for conjecture as to the date of the event. For the upheaving of the Pyrenees may have been going on when the animals of the Maestricht beds flourished, or during the indefinite ages which may have elapsed between their extinction and the introduction of the Eocene tribes, or during the Eocene epoch. or between that and the Miocene. Or the rise may have been going on continuously throughout several or all of these periods.

But this is not all; we must include within the possible space of time wherein the convulsions may have happened, part of the epochs both of the chalk and of the Miocene species. We have stated, that the newer Pliocene beds in Sicily have been raised during the newer Pliocene epoch, partly, perhaps, in the Recent, but this latter supposition will lend equal support to our present argument. Now, it is evident that the greater part of the species of testacea which pre-existed in the Mediterranean have survived the elevation of the newer Pliocene beds in Sicily, and in the same manner there is no reason to conclude that the rise of the chalk in the Pyrenees exterminated the animals which lived in the sea wherein the chalk was formed. In that case, a series of convulsions may not only have begun, but may even have been completed before the era when the Maestricht beds originated.

In like manner the sea may have been inhabited by Miocene testacea for ages before the deposition of those particular Miocene strata which occur at the foot of the Pyrenees, and the disturbing forces may have operated in the Miocene period, notwithstanding the horizontality of the tertiary formations of that age.

In order to illustrate the grave objections above advanced, which are aimed at the validity of the whole of de Beaumont's reasoning, let the reader suppose, that in some country three styles of architecture had prevailed in succession, each for a period of 1000 years; first the Greek, then the Roman, and then the Gothic; and that a tremendous earthquake was known to have occurred in the same district during some part of the three periods, -- a shock of such violence as to have levelled to the ground every building. If an antiquary, desirous of discovering the date of the catastrophe, should first arrive at a city where several Greek temples were lying in ruins and half engulphed in the earth, while many Gothic edifices were standing uninjured, could he determine on these data the era of the shock? Certainly not. He could merely affirm that it happened at some period after the introduction of the Greek style, and before the Gothic had fallen into disuse. Should he pretend to define the date of the convulsion with greater precision, and decide that the earthquake must have occurred in the interval between the Greek and Gothic periods, that is to say, when the Roman style was in use, the fallacy in his reasoning would be too palpable to escape detection for a moment.

Yet such is the nature of the erroneous induction which we are now exposing. For, in the example above proposed, the erection of a particular edifice is not more distinct from the period of architecture in which it may have been raised, than is the deposition of chalk, or any other set of strata, from the geological epoch to which they may belong. Yet, if on these grounds we are compelled to include in the interval in which the elevation of each chain may have happened, the periods of those two classes of formations before alluded to, the deranged and the horizontal, it follows that, even if all the facts appealed to by de Beaumont are correct, his intervals are of indefinite extent. He is not even warranted in asserting that the chain A (p. 340) is older than B (p. 341), if he means that it was elevated at a different geological period, for both may have been upheaved during the same period, namely, that when the strata c were formed.

Supposed parallelism of contemporaneous lines of elevation. -- So, also, when he infers that two chains were simultaneously upraised, the proof fails, since the close of the period of the disturbed strata and the commencement of the era of the undisturbed must be added to the lapse of time during which the two chains may have originated, and in separate parts of which each may have been produced. With the insufficiency of the above evidence the whole force of the argument in support of the parallelism of lines of contemporaneous movement is annihilated.

This hypothesis, indeed, of parallelism appears, even as stated by the author, in some degree at variance with itself. When certain European chains had been assumed to have been raised at the same time on the data already impugned, it was found that several of these contemporaneous chains had a parallel direction. Hence it was presumed to be a general law in geological dynamics that the chains upheaved at the same time are parallel. For example, it was said that the Pyrenees and other coetaneous chains, such as the northern Apennines, have a direction about W. N. W. and E. S. E., and to this line the Alleghanies in North America conform, as also the ghauts of Malabar, and certain chains in Egypt, Syria, northern Africa, and other countries; and from this mere conformity in direction it was presumed that all these mountain-ranges were thrown up simultaneously.

To select another example, the principal chain of the Alps, differing in age and direction from the Pyrenees, is parallel to the Sierra Morena, the Balkan, the chain of Mount Atlas, the central chain of the Caucasus, and the Himalaya. All these ridges, therefore, were probably heaved up by the same paroxysmal convulsion! The western Alps, on the other hand, rose at a still earlier period, when the parallel chains of Kiol, in Scandinavia, certain chains in Morocco, and the littoral Cordillera of Brazil, were formed!

Not only do these speculations refer to mountains never touched, as M. Boue remarks, by the hammer of the geologist, but they proceed on the supposition, that in these distant chains the geological and geographical axes always coincide. Now we know that in Europe the strike [9] of the beds is not always parallel to the direction of the chain. As an exception, we may instance that pointed out by Von Dechen, [10] who states that in the Hartz the direction or strike of the strata of slate and greywacke is sometimes from E. and W. and frequently N. E. and S. W.; whereas the geographical direction of the mountain-chain is decidedly from E. S. E. to W. N. W.

In addition to these uncertainties, which should, in the present state of science, have deterred a geologist even from speculating on the phenomena of unexplored regions, the important admission is made by M. de Beaumont himself, that the elevating forces, whose activity must be referred to different epochs, have sometimes acted in Europe in parallel lines. 'It is worthy of remark, says that author, that the directions of three systems of mountains, namely, first, that of the Pilas and the Cote d'Or; secondly, that of the Pyrenees; and thirdly, that of the islands of Corsica and Sardinia, are respectively parallel to three other systems, namely, first, that of Westmoreland and the Hunsdruck, secondly, that of the Ballons (or Vosges) and the hills of the Bocage, in Calvados; and thirdly, the system of the north of England. The corresponding directions only differ in a few degrees, and the two series have succeeded each other in the same order, leading to the supposition, that there has been a kind of periodical recurrence of the same, or nearly the same, directions of elevation.' [11]

Here then we have three systems of mountains, A, B, C, which were formed at successive epochs, and have each a different direction; and we have three other systems, D, E, F, which, although they are assumed to have the same strike, as the series first mentioned (D corresponding with A, E with B, and F with C), are nevertheless declared to have been formed at different periods. On what principle, then, is the age of an Indian or transatlantic chain referred to one of these European lines rather than another? why is the age of the Alleghanies, or the ghauts of Malabar, determined by their parallelism to B rather than to E, to the Pyrenees rather than to the Ballons of the Vosges?

The substance of the last objection has been anticipated by M. Boue, [12] who, at the same time, disputes the accuracy of many of the facts appealed to by M. de Beaumont. Other errors in fact have also been pointed out by MM. Keferstein, Von Dechen, and De la Beche. [13] But the incorrectness of some of these data might not have affected the validity of the general theory if it had been founded on a solid basis. In regard to the Alps, MM. Necker and Studer have informed me, that on re-examining that chain since de Beaumont's memoirs were published, they have been unable to reconcile the phenomena there exhibited with his views relating to the strike and dip of that great chain.

Professor Sedgwick has declared his adhesion to the opinions of de Beaumont; but we are not aware that he had maturely considered them in all their bearings; and he has stated some important objections to the doctrine of 'parallelism.' [14] Among others, he has remarked, that in consequence of the spheroidal figure of the earth, different mountain-chains, running north and south, cannot be strictly said to be parallel, since they would, if prolonged, cross each other at the poles.

Objections of Mr. Conybeare. -- An inquiry was proposed, in 1831, by the British Association for the Promotion of Science, 'whether the theory of M. Elie de Beaumont, concerning the parallelism of lines of elevation of the same geological era, is agreeable to the phenomena as exhibited in Great Britain?' Mr. Conybeare, in the first part of his report, in answer to this inquiry, [15] points out many lines of distinct ages in England which are exactly parallel, and others which, according to the rules laid down by M. de Beaumont, ought to agree in age with certain continental chains, and yet do not, having an entirely different direction. He imagines that the general strike of the secondary strata of our island, from N. E. to S. W., has been the result, not of any violent or single convulsion, but, on the contrary, of 'a gradual, gentle, and protracted upheaving, continued without interruption during the whole period of the formation of all these strata.'

The same author has also adverted to some of the difficulties attending the exact determination of the geological epochs of the elevation of each chain, especially where the disturbed and undisturbed strata in contact are not very nearly of the same age, or, as he expresses it, 'where they are not terms immediately following one another in the regular geological series.' [16] We were forcibly struck with the uncertainty arising from this cause during a late tour, when we discovered that at the eastern end of the Pyrenees, on the side of France, tertiary strata of the older Pliocene epoch abut against vertical mica-schist; while at the western extremity of the same mountain-range we find the disturbed series to consist of chalk, the undisturbed of Miocene strata. The chain is then lost in the sea, and we are precluded from pushing our investigations farther to the westward; but if we could follow the strike of the beds in their submarine prolongation, who shall say that the tilted group might not be found to include strata newer than the chalk, the horizontal beds older than the Miocene?

Supposed instantaneous rise of a mountain-chain. -- 'Everything shows, says M. Elie de Beaumont, that the instantaneous elevation of the beds of a whole mountain-chain is an event of a different order from those which we daily witness.' [17]

We observe with pleasure the rejection, by Mr. Conybeare, of the hypothesis that the disturbances affecting large geographical districts have been produced at one blow, rather than by a series of shocks which may have occurred at intervals through a long period of ages, and that he contends for the greater probability of successive convulsions, on the ground that such an hypothesis is most conformable to the only analogy presented by actual causes -- 'the operations of volcanic forces.' [18]

Modern 'Volcanic lines not parallel. -- By that analogy we are led to suppose that the lines of convulsion, at former epochs, were far from being uniform in direction, for the trains of active volcanos are not parallel, as everyone is aware who has studied Von Buch's masterly survey of the general range of volcanic lines over the globe, [19] and the elevations and subsidences caused by modern earthquakes, although they may sometimes run in parallel lines within limited districts, have not been observed to have a common direction in distant and independent theatres of volcanic action.

We do not doubt that in many regions the ridges, troughs, and fissures caused by modern earthquakes, are, to a certain extent, parallel to each other, but only within a limited range of country; and such appears to have been the case in many districts at former eras. The anticlinal lines of the Weald Valley, before alluded to, and of the Isle of Wight, may, in this manner, have been contemporaneous, that is to say, both may have been formed in some part of the Eocene period, -- an hypothesis which does not involve the theory of their having been due to paroxysmal convulsions during one part of that vast period.

It should be observed, that as some trains of burning volcanos are parallel to each other, so at all periods some independent lines of elevation may be parallel accidentally, or not in obedience to any known law of parallelism; but, on the contrary, as exceptions to the general rule. We hope that the speculations of M. de Beaumont will be useful in inducing geologists to inquire how far the uniformity in the direction of the beds, in a region which has been agitated at any particular period, may extend; but we trust that travellers will not be led away with the idea that, on arriving in India, America, or New Holland, they have only to use the compass and examine the strike of the beds in order to discover the relative era of the movement by which they were upraised. Such problems can in truth be only solved by a patient and laborious investigation of the sedimentary formations occurring in each region, and especially by the study of their organic remains.

Difficulties attending the determination of the relative age of mountains. -- If we are asked whether we cherish no expectation of fixing a chronological succession of epochs of elevation of different mountain-chains, we reply, that in the present state of our science we have no hope of making more than a loose approximation to such a result. The difficulty depends chiefly on the broken and interrupted nature of the series of sedimentary formations hitherto brought to light, which appears so imperfect that we can rarely be sure that the memorials of some great interval of time are not wanting between two groups now classed as consecutive. Another great source of ambiguity arises from the small progress which we have yet made in identifying strata in countries somewhat distant from each other.

There may be instances where the same set of strata, preserving throughout a perfect identity of mineral character, may be traced continuously from the flanks of one independent mountain-chain to the base of another, the beds being vertical or inclined in one chain, and horizontal in the other. We might then decide with confidence, according to the method proposed by M. de Beaumont, on the relative eras when these chains had undergone disturbance; and from one point thus securely established, we might proceed to another, until we had determined the dates of many neighbouring lines of convulsion.

We fear that the cases are rare where such evidence can be obtained; and, {or the most part, we can identify the age of strata, not by their continuity and homogeneous mineral character, but by organic remains. When by their aid we prove strata to be contemporaneous, we must generally speak with great latitude, merely intending that they were deposited in the same geological epoch during which certain animals and plants flourished.

_______________

Notes:

1. Ann. des Sci. Nat., Septembre, Novembre, et Decembre, 1829. Revue Francaise, No. 15, May, 1830. The last version by M. de B. which I have seen is in the Phil. Mag. and Annals, No. 58, new series, p. 241.

2. Vol. i. pp. 64 and 88, and Second Edition, pp. 73 and 100; vol. ii. p. 196, and Second Edition, p. 203.

3. Vol. i. p. 79, and Second Edition, p. 90.

4. See particularly from p. 26 to p. 34.

5. See above, p. 148.

6. Phil. Mag. and Annals, No. 58, new series, p. 242.

7. Phil. Mag. and Annals, No. 58, new series, p. 243.

8. The fossils which I collected in company with Captain S. E. Cook, R. N,. from the newest secondary beds on the flanks of the Pyrenees, near Bayonne, were examined by M. Deshayes, and found identical with species of the chalk near Paris.

9. The term 'strike' has been recently adopted by some or our most eminent geologists from the German 'streich,' to signify what our miners call the 'line of bearing' of the strata. Such a term was much wanted, and as we often speak or striking off in a given direction, the expression seems sufficiently consistent with analogy in our language.

10. Trans. of De la Beebe's Geol. Manual, p. 41.

11. Phil. Mag. and Annals, No. 58, new series, pp. 255, 256.

12. Journ. de Geologie, tome iii. p. 338.

13. Geol. Manual, p. 501, and Second Edition, p. 519.

14. Anniv. Address to the Geol. Soc., Feb., 1831.

15. Phil. Mag. and Journ. of Sci., No. 2, third series, p. 118. The second part, I believe, is not yet published.

15. Ibid., p. 120.

16. Phil. Mag. and Annals, No. 58, new series, p. 243.

17. Phil. Mag. and Journ. of Sci., No. 2, third series, p. 121.

18. Physical. Besch. der Canarischen Inseln. Berlin, 1825.
admin
Site Admin
 
Posts: 28480
Joined: Thu Aug 01, 2013 5:21 am

Re: Principles of Geology, by Charles Lyell

Postby admin » Fri Jul 17, 2015 3:06 am

CHAPTER 25

On the rocks usually termed 'Primary' – Their relation to volcanic and sedimentary formations – The 'primary' class divisible into stratified and unstratified – Unstratified rocks called Plutonic – Granite veins – Their various forms and mineral composition – Proofs of their igneous origin – Granites of the same character produced at successive eras – Some of these newer than certain fossiliferous strata – Difficulty of determining the age of particular granites – Distinction between the volcanic and the plutonic rocks – Trappean rocks not separable from the volcanic – Passage from trap into granite – Theory of the origin of granite at every period from the earliest to the most recent

ON THE ROCKS COMMONLY CALLED PRIMARY.

WE shall now treat of the class of rocks usually termed 'primary,' a name which, as we shall afterwards show, is not always applicable, since the formations so designated sometimes belong to different epochs, and are not, in every case, more ancient than the secondary strata. In general, however, this division of rocks may justly be regarded as of higher antiquity than the oldest secondary groups before described, and they may, therefore, with propriety be spoken of in these concluding chapters, for we have hitherto proceeded in our retrospective survey of geological monuments from the newer to those of more ancient date.

In order to explain to the reader the relation which we conceive the rocks termed' primary' to bear to the tertiary and secondary formations, we shall resume that general view of the component parts of the earth's crust of which we gave a slight sketch in the preliminary division of our subject in the 2nd chapter. [1]

We there stated that sedimentary formations, containing organic remains, occupy a large part of the surface of our continents, but that here and there volcanic rocks occur, breaking through, alternating with, or covering the sedimentary deposits, so that there are obviously two orders of mineral masses formed at the surface which have a distinct origin, the aqueous and the volcanic.

Image
No. 84.
a, Formations called primary (stratified and unstratified).
b, Aqueous formations.
c, Volcanic rocks.


Besides these, however, there is another class, which cannot be assimilated precisely to either of the preceding, and which is often seen underlying the sedimentary, or breaking up to the surface in the central parts of mountain-chains, constituting some of the highest lands, and, at the same time, passing down and forming the inferior parts of the crust of the earth. This class, usually termed 'primary,' is divisible into two groups, the stratified and the unstratified. The stratified consists of the rocks called gneiss, mica-schist, argillaceous- schist (or clayslate), hornblende-schist, primary limestone, and some others. The unstratified, or Plutonic, is composed in great measure of granite, and rocks closely allied. to granite. Both these groups agree in having, for the most part, a highly crystalline texture, and in not containing organic remains.

Plutonic rocks. -- The unstratified crystalline rocks have been very commonly called Plutonic, from the opinion that they were formed by igneous action at great depths, whereas the volcanic, although they also have risen up from below, have cooled from a melted state upon or near to the surface. The theory conveyed by the name Plutonic is, we believe, correct. Granite, porphyry, and other rocks of the same family, often occur in large amorphous masses, from which small veins and dikes are sent off, which traverse the stratified rocks called 'primary,' precisely in the manner in which lava is seen in some places to penetrate the secondary strata.

Granite Veins. -- We find also one set of granite veins intersecting another, and granitiform porphyries intruding themselves into granite, in a manner analogous to that of the volcanic dikes of Etna and Vesuvius, where they cut and shift each other, or pass through alternating beds of lava and tuff.

Image
No. 85: Granite veins traversing stratified rocks.

The annexed diagram will explain to the reader the manner in which these granite veins often branch off' from the principal mass. Those on the right-hand side, and in the middle, are taken from Dr. Macculloch's representation of veins passing through the gneiss at Cape Wrath, in Scotland. [2] The veins on the left are described, by Captain Basil Hall, as traversing the argillaceous schist of the Table- Mountain at the Cape of Good Hope. [3]

Image
No. 86: Granite veins traversing gneiss at Cape Wrath, in Scotland.

We subjoin another sketch from Dr. Macculloch's interesting representations of the granite veins in Scotland, in which the contrast of colour between the vein and some of the dark varieties of hornblende-schist associated with the gneiss renders the phenomena more conspicuous.

The following sketch of a group of granite veins in Cornwall is given by Messieurs Von Oeynhausen and Von Dechen. [4] The main body of the granite here is of a porphyritic appearance with large crystals of felspar; but in the veins it is fine-grained and without these large crystals. The general height of the veins is from 16 to 20 feet, but some are much higher.

Image
No. 87: Granite veins passing through Hornblende slate, Carnsilver Cove, Cornwall.

The vein-granite of Cornwall very generally assumes a finer grain, and frequently undergoes a change in mineral composition, as is very commonly observed in other countries. Thus, according to Professor Sedgwick, the main body of the Cornish granite is an aggregate of mica, quartz, and felspar; but the veins are sometimes without mica, being a granular aggregate of quartz and felspar. In other varieties quartz prevails to the almost entire exclusion both of felspar and mica; in others, the mica and quartz both disappear, and the vein is simply composed of white granular felspar. [5]

Changes are sometimes caused in the intersected strata very analogous to those which the contact of a fused mass might be supposed to produce.

Image
No. 88: Junction of granite and limestone in Glen Tilt.
a, Granite.
b, Limestone.
c, Blue argillaceous schist.


The above diagram from a sketch of Dr. Macculloch, represents the junction of the granite of Glen Tilt in Perthshire, with a mass of stratified limestone and schist. The granite, in this locality, often sends forth so many veins as to reticulate the limestone and schist, the veins diminishing towards their termination to the thickness of a leaf of paper or a thread. In some places fragments of granite appear entangled as it were in the limestone, and are not visibly connected with any larger mass, while sometimes, on the other hand, a lump of the limestone is found in the midst of the granite. The ordinary colour of the limestone of Glen Tilt is lead blue, and its texture large grained and highly crystalline; but where it approximates to the granite" particularly where it is penetrated by the smaller veins, the crystalline texture disappears, and it assumes an appearance exactly resembling that of horn-stone. The associated argillaceous schist often passes into hornblende slate, where it approaches very near to the granite. [6]

In the plutonic, as in the volcanic rocks, there is every gradation from a tortuous vein to the most regular form of a dike, such as we have described as intersecting the tuffs and lavas of Vesuvius and Etna. In these dikes of granite, which may be seen, among other places, on the southern flank of Mount Battoch, one of the Grampians, the opposite walls sometimes preserve an exact parallelism for a considerable distance. It is not uncommon for one set of granite veins to intersect another, and sometimes there are three sets, as in the environs of Heidelberg, where the granite of the right bank of the Rhine is seen to consist of three varieties differing in colour, grain, and various peculiarities of mineral composition. One of these, which is evidently the second in age, is seen to cut through an older granite, and another, still newer, traverses both the second and the first. These phenomena were lately pointed out to me by Professor Leonhard at Heidelberg.

In Shetland there are two kinds of granite. One of these, composed of hornblende, mica, felspar, and quartz, is of a dark colour, and is seen underlying gneiss. The other is a red granite which penetrates the former everywhere in veins. [7]

Granites of different ages. -- It was formerly supposed that granite was the oldest of rocks, the mineral product of a particular period or state of the earth formed long antecedently to the introduction of organic beings into the planet. But it is now ascertained that this rock has been produced again and again, at successive eras, with the same characters, penetrating the stratified rocks in different regions, but not always associated with strata of the same age. Nor are organic remains always entirely wanting in the formations invaded by granite, although their absence is more usual. Many well authenticated exceptions to the rule are now established on the authority of numerous observers, amongst the earliest of whom we may cite Von Buch, who discovered in Norway a mass of granite overlying an ancient secondary limestone, containing orthocerata and other shells and zoophytes. [8]

A considerable mass of granite in Sky is described by Dr. Macculloch as incumbent on limestone and shale, which are of the age of the English lias. [9] The limestone, which, at a greater distance from the granite, contains shells, exhibits no traces of them near the junction of the igneous rock, where it has been converted into a pure crystalline marble. [10]

This granite of Sky was at first termed 'Syenite,' by which name many geologists have denominated the more modern granites; but authors have entirely failed in their attempt to establish a distinction between granites and syenites on mineralogical characters. The latter have sometimes been defined to consist of a triple compound of felspar, quartz, and hornblende, but the oldest granites are very commonly composed of these ingredients only. In his later publications Dr. Macculloch has with great propriety, we think, called the plutonic rock of Sky a granite. [11]

In different parts of the Alps a comparatively modern granite is seen penetrating through secondary strata, which contain belemnites, and other fossils, and are supposed to be referrible to the age of the English lias. According to the observations of M. Elie de Beaumont and Hugi, masses of this granite are sometimes found partially overlying the secondary beds, and altering them in a manner which we shall describe more particularly when we treat of the changes in composition and structure superinduced upon sedimentary deposits in contact with Plutonic rocks [12] (see wood-cut, No. 90, p. 371).

In such examples we can merely affirm, that the granite is newer than a secondary formation containing belemnites, but we can form no conjecture when it originated, not even whether it be of secondary or tertiary date. It is, indeed, very necessary to be on our guard against the inference that a granite is usually of about the same age as the group of strata into which it has intruded itself, for in that case we shall be inclined to assume rashly that the granites found penetrating a more modern secondary rock, such as the lias for example, are much newer than those found invading strata older than the carboniferous series. The contrary may often be true, for the plutonic rock which was last in a melted state, may not have been forced up anywhere so near the surface as to enter into the newer groups of strata, and it may have been injected into a part of the earth's crust formed exclusively of the older sedimentary formations.

'In a deep series of strata,' says Dr. Macculloch, 'the superior or distant portions may have been but slightly disturbed, or have entirely escaped disturbance, by a granite which has not emitted its veins far beyond its immediate boundary. However certain, therefore, it may be, that any mass of granite is posterior to the gneiss, the micaceous schist, or the argillaceous schists, which it traverses, or into which it intrudes, we are unable to prove that it is not also posterior to the secondary strata that lie above them.' [13]

There can be no doubt, however, that some granites are more ancient than any of our regular series which we identify by organic remains, because there are rounded pebbles of granite, as well as gneiss, in the conglomerates of the oldest fossiliferous groups.

Distinction between volcanic and plutonic rocks -- Trap. -- The next point to consider is the distinction between the plutonic and volcanic rocks. When geologists first began to examine attentively the structure of the northern parts of Europe, they were almost entirely ignorant of the phenomena of existing volcanos, and when they met with basalt and other rocks composed chiefly of augite, hornblende, and felspar, which are now admitted by all to have been once in a state of fusion, they were divided in opinion whether they were of igneous or of aqueous origin. We have shown in our sketch of the history of geology in the first volume, how much the polemical controversies on this subject retarded the advancement of the science, and how slowly the analogy of the rocks in question to the products of burning volcanos was recognized. Most of the igneous rocks first investigated in Germany, France, and Scotland, were associated with marine strata, and in some places they occurred in tabular masses or platforms at different heights, so as to form on the sides of some hills a succession of terraces or steps, from which circumstance they were called 'trap' by Bergman (from trappa, Swedish for a staircase), a name afterwards adopted very generally into the nomenclature of the science.

When these trappean rocks were compared with lavas produced in the atmosphere, they were found to be in general less porous and more compact; but in this instance the terms of comparison were imperfect, for a set of rocks, formed almost entirely under water, was contrasted with another which had cooled in the open air.

Yet the ancient volcanos of Central France were classed, in reference probably to their antiquity, with the trap rocks, although they afford perfect counterparts to existing volcanos, and were evidently formed in the open air. Mont Dor and the Plomb du Cantal, indeed, may differ in many respects from Vesuvius and Etna in the mineral constitution and structure of their lavas; but it is that kind of difference which we must expect to discover when we compare the products of any two active volcanos, such as Teneriffe and Hecla, or Hecla and Cotopaxi.

The amygdaloidal structure in many of the trap formations proves that they were originally cellular and porous like lava, but the cells have been subsequently filled up with silex, carbonate of lime, zeolite, and other ingredients which form the nodules. Dr. Macculloch, after examining with great attention the igneous rocks of Scotland, observes' that it is a mere dispute about terms to refuse to the ancient eruptions of trap the name of submarine volcanos, for they are such in every essential point, although they no longer eject fire and smoke.' [14]

The same author also considers it not improbable that some of the volcanic rocks of the same country may have been poured out in the open air. [15]

The recent examination of the igneous rocks of Sicily, especially those of the Val di Noto, has proved that all the more ordinary varieties of European trap have been produced under the waters of the sea in the Newer Pliocene period, that is to say, since the Mediterranean has been inhabited by a great proportion of the existing species of testacea. We are, therefore, entitled to feel the utmost confidence, that if we could obtain access to the existing bed of the ocean, and explore the igneous rocks poured out within the last 5000 years beneath the pressure of a sea of considerable depth, we should behold formations of modern date scarcely distinguishable from the most ancient trap rocks of our island. We cannot, however, expect the identity to be perfect, for time is ever working some alteration in the composition of these mineral masses, as, for example, by converting porous lava into amygdaloids.

Passage from trap into granite. -- If a division be attempted between the trappean and volcanic rocks, it must be made between different parts of the same volcano,-nay even the same rock, which would be called 'trap,' where it fills a fissure and has assumed a solid crystalline form on slow cooling, must be termed volcanic, or lava, where it issues on the flanks of the mountain. Some geologists may perhaps be of opinion that melted matter, which has been poured out in the open air, may be conveniently called volcanic, while that which appears to have cooled at the bottom of the sea, or under pressure, but at no great depth from the surface, may be termed 'trap;' but we believe that such distinctions will lead only to confusion, and that we must consider trap and volcanic as synonymous. On the other hand, the difficulty of discriminating the volcanic from the plutonic rocks is sufficiently great; for we must draw an arbitrary line between them, there being an insensible passage from the most common forms of granite into trap or lava.

'The ordinary granite of Aberdeenshire,' says Dr. Macculloch, 'is the usual ternary compound of quartz, felspar, and mica, but sometimes hornblende is added to these, or the hornblende is substituted for the mica. But in many places a variety occurs which is composed simply of felspar and hornblende, and in examining more minutely this duplicate compound, it is observed in some places to assume a fine grain, and at length to become undistinguishable from the greenstones of the trap family. It also passes in the same uninterrupted manner into a basalt, and at length into a soft claystone, with a schistose tendency on exposure, in no respect differing from those of the trap islands of the western coast.' [16] The same author mentions, that in Shetland a granite composed of hornblende, mica, felspar, and quartz, graduates in an equally perfect manner into basalt. [17]

It would be easy to multiply examples to prove that the granitic and trap-rocks pass into each other, and are merely different forms which the same elements have assumed according to the different circumstances under which they have consolidated from a state of fusion. What we have said respecting the mode of explaining the different texture of the central and external parts of the Vesuvian dikes may enable the reader in some measure to comprehend how such differences may originate. [18]

The same lava which is porous where it has flowed over from the crater, and where it has cooled rapidly and under comparatively slight pressure, is compact and porphyritic in the dike. Now these dikes are evidently the channels of communication between the crater and the volcanic foci below; so that we may suppose them to be continuous to the depth of several hundred fathoms, or perhaps two or three miles, or even more; and the fluid matter below, which cools and consolidates slowly under so enormous a pressure, may be supposed to acquire a very distinct texture and become granite.

If it be objected that we do not find in mountain-chains volcanic dikes passing upwards into lava, and downwards into granite, we may answer that our vertical sections are usually of small extent, and it is enough that we find in certain localities a transition from trap to porous lava, and in others a passage from granite to trap. It should also be remembered, that a large proportion of the igneous rocks, when first formed, cannot be supposed to reach the surface, and these may assume the usual granitic texture without graduating into trap, or into such lava and scoriae as are found on the flanks of a volcanic cone.

Theory of the origin of granite at all periods. -- It is not uncommon for lava-streams to require more than ten years to cool in the open air, and a much longer period where they are of great depth. The melted matter poured out from Jorullo, in Mexico, in the year 1759, which accumulated in some places to the height of 550 feet, was found to retain a high temperature half a century after the eruption. [19] For what immense periods, then, must we not conclude that great masses of subterranean lava in the volcanic foci may remain in a red hot or incandescent state, and how gradual must be the process of refrigeration! This process may be sometimes retarded for an indefinite period, by the accession of fresh supplies of heat, for we find that the lava in the crater of Stromboli, one of the Lipari islands, has been in a state of constant ebullition for the last 2000 years, and we must suppose this fluid mass to communicate with some cauldron or reservoir of fused matter below. In the Isle of Bourbon, also, where there has been an emission of lava once in every two years for a long period, we may infer that the lava below is permanently in a state of liquefaction.

When melted matter is injected into the fissures of a contiguous rock at a considerable depth, it may cool rapidly if that rock has not acquired a high temperature; but suppose, on the contrary, that it has been heated, and still continues for centuries, or thousands of years, at a red heat, the vein may acquire a highly crystalline texture.

The great pressure of a superincumbent mass, and exclusion from contact with air or water, are probably the usual conditions necessary to produce the granitic texture; but the same may sometimes be superinduced at a slighter distance from the surface by slow refrigeration, when additional supplies of heat check, from time to time, the cooling process and cause it to be indefinitely protracted.

If, for the reasons above alluded to, we conceive it probable that plutonic rocks have originated in the nether parts of the earth's crust, as often as the volcanic have been generated at the surface, we may imagine that no small quantity of the former class has been forming in the recent epoch, since we suppose that about 2000 volcanic eruptions may occur in the course of every century, either above the waters of the sea or beneath them. [20]

We may also infer, that during each preceding period, whether tertiary or secondary, there have been granites and granitiform rocks generated, because we have already discovered the monuments of ancient volcanic eruptions at almost every period.

In the next chapter we shall endeavour to show, that in consequence of the great depths at which the plutonic rocks usually originate, and the manner in which they are associated with the older sedimentary strata of each district, it is rarely possible to determine with exactness their relative age. Yet there is reason to believe that the greater portion of the plutonic formations now visible are of higher antiquity than the oldest secondary strata. We shall also endeavour to point out, that this opinion is by no means inconsistent with the theory that equal quantities of granite may have been produced in succession, during equal periods of time, from the earliest to the most modern epochs.

_______________

Notes:

1. See above, p. 8.

2. Western Islands, plate 31.

3. Account of the structure of the Table-Mountain, &c., Trans. Roy. Soc. Edin., vol. vii.

4. Phil. Mag. and Annals, No. 27, new Series, March, 1829.

5. On Geol. of Cornwall. Trans. of Cambridge Soc., vol. i. p. 124.

6. Macculloch, Geol. Trans., vol. iii. p. 259.

7. Macculloch, Syst. of Geol., vol. i. p. 58.

8. Travels through Norway and Lapland, p. 45. London, 1813.

9. See Murchison, Geol. Trans., 2nd Series, vol. ii. part ii. p. 311-321.

10. Western Islands, vol. i. p. 330.

11. Syst. of Geol., vol. i. p. 150.

12. Elie de Beaumont, Sur les Montagnes de 1'Oisans, Mem. de la Soc. d'Hist. Nat. de Paris, tome v. Hugi, Natur, Historische Alpenreise, Soleure, 1830.

13. Syst. of Geol., vol. i. p. 136.

14. Syst. of Geol., vol. ii. p. 114.

15. Ibid.

16. Syst. of Geol., vol. i. p. 157.

17. Ibid., p. 158.

18. See above, p. 124.

19. See vol. i. p. 378, and Second Edition, p. 433.

20. See vol. i. chap. xxii.
admin
Site Admin
 
Posts: 28480
Joined: Thu Aug 01, 2013 5:21 am

Re: Principles of Geology, by Charles Lyell

Postby admin » Fri Jul 17, 2015 3:08 am

CHAPTER 26

On the stratified rocks usually called 'primary' – Proofs from the disposition of their strata that they were originally deposited from water – Alternation of beds varying in composition and colour – Passage of gneiss into granite – Alteration of sedimentary strata by trappean and granitic dikes – Inference as to the origin of the strata called 'primary' – Conversion of argillaceous into hornblende schist – The term 'Hypogene' proposed as a substitute for primary – 'Metamorphic' for 'stratified primary' rocks – No regular order of succession of hypogene formations – Passage from the metamorphic to the sedimentary strata – Cause of the high relative antiquity of the visible hypogene formations – That antiquity consistent with the hypothesis that they have been produced at each successive period in equal quantities – Great volume of hypogene rocks supposed to have been formed since the Eocene period – Concluding remarks

ON THE STRATIFIED ROCKS CALLED 'PRIMARY.'

WE stated in the last chapter, that the rocks usually termed 'primary' are divisible into two natural classes, the stratified and the unstratified. The propriety of the term stratified, as applied to the first-mentioned class, will not be questioned when the rocks so designated are carefully compared with strata known to result from aqueous deposition.

Mode of stratification. -- If we examine gneiss, which consists of the same materials as granite, or mica-schist which is a binary compound of quartz and mica, or clay-slate, or any other member of the so-called primary division, we find that it is made up of a succession of beds, the planes of which are, to a certain extent, parallel to each other, but which frequently deviate from parallelism in a manner precisely analogous to that exhibited by sedimentary formations of all ages. 'The resemblance is often carried farther, for in the crystalline series we find beds composed of a great number of layers placed diagonally, as we have shown to be the case in the Crag and other formations. [1] This disposition of the layers is illustrated in the accompanying diagram, in which I have represented carefully the stratification of a coarse argillaceous schist, which I examined in the Pyrenees, part of which approaches in character to a green and blue roofing slate, while part is extremely quartzose, the whole mass passing downwards into micaceous schist. The vertical section here exhibited is about three feet in height, and the layers are sometimes so thin that fifty may be counted in the thickness of an inch. Some of them consist of pure quartz.

Image
No. 89: Lamination of clag-slate, Montagne de Seguinat, near Gavarnie, in the Pyrenees.

The stratification now alluded to must not be confounded with that fissile texture sometimes observed in the older rocks, by virtue of which they divide in a direction different both from the general planes of stratification and from the planes of those transverse layers of which a single stratum may be made up.

Another striking point of analogy between the stratification of the crystalline formations and that of the secondary and tertiary periods is the alternation in each of beds varying greatly in composition, colour, and thickness. We observe, for instance, gneiss alternating with layers of black hornblende-schist, or with granular quartz or limestone, and the interchange of these different strata may be repeated for an indefinite number of times. In like manner, mica-schist alternates with chlorite-schist, and with granular limestone in thin layers.

As we observe in the secondary and tertiary formations strata of pure siliceous sand alternating with micaceous sand and with layers of clay, so in the 'primary' we have beds of pure quartz rock alternating with mica-schist and clay-slate. As in the secondary and tertiary series we meet with limestone alternating again and again with micaceous or argillaceous sand, so we find in the 'primary' gneiss and mica-schist alternating with pure and impure granular limestones.

Passage of gneiss into granite -- If, then, reasoning from the principle that like effects have like causes, we attribute the stratification of gneiss, mica-schist, and other associated rocks, to sedimentary deposition from a fluid, we encounter this difficulty, that there is often a transition from gneiss, one of the stratified series, into granite, which, as we have shown, is of igneous origin. Gneiss is composed of the same ingredients as granite, and its texture is equally crystalline. It sometimes occurs in thick beds, and in these the rock is often quite undistinguishable, in hand specimens, from granite; yet the lines of stratification are still evident. These lines imply deposition from water, while the passage into granite would lead us to infer an igneous origin. In what manner can we reconcile these apparently conflicting views? The Huttonian hypothesis offers, we think, the only satisfactory solution of this problem. According to that theory, the materials of gneiss were originally deposited from water in the usual form of aqueous strata, but these strata were subsequently altered by their proximity to granite, and to other plutonic masses in a state of fusion, until they assumed a granitiform texture. The reader will be prepared, by what we have said of granite, to conclude, that when voluminous masses of melted rock have been for ages in an incandescent state, in contact with sedimentary deposits, they must produce some alteration in their texture, and this alteration may admit of every intermediate gradation between that resulting from perfect fusion, and the slightest modification which heat can produce.

The geologist has been conducted, step by step, to this theory by direct experiments on the fusion of rocks in the laboratory, and by observation of the changes in the composition and texture of stratified masses, as they approach or come in contact with igneous veins and dikes. In studying the latter class of phenomena, we have the advantage of examining the condition of the rock at some distance from the dike where it has escaped the influence of heat, and its state where it has been near to, or in contact with, the fused mass. The changes thus exhibited may be regarded as the results of a series of experiments, made on a great scale by nature under every variety of condition, both as relates to the mineral ingredients of the rocks, the intensity of heat or pressure, the celerity or slowness of the cooling process, and other circumstances.

Strata altered by volcanic dikes -- Plas Newydd. -- We shall select a few examples of these alterations in illustration of our present argument. One of the most interesting is the modification of strata in the proximity of a volcanic dike near Plas Newydd, in Anglesea, described by Professor Henslow. The dike is 134 feet wide, and consists of basalt (dolerite of some authors), a compound of felspar and augite. Strata of shale and argillaceous limestone, through which it cuts perpendicularly, are altered to a distance of thirty, or even in some places to thirty-five feet, from the edge of the dike. The shale, as it approaches the basalt, becomes gradually more compact, and is most indurated where nearest the junction. Here it loses part of its schistose structure, but the separation into parallel layers is still discernible. In several places the shale is converted into hard porcellanous jasper. In the most hardened part of the mass the fossil shells, principally Productae, are nearly obliterated, yet even here their impressions may frequently be traced. The argillaceous limestone undergoes analogous mutations, losing its earthy texture as it approaches the dike, and becoming granular and crystalline. But the most extraordinary phenomenon is the appearance in the shale of numerous crystals of analcime and garnet, which are distinctly confined to those portions of the rock affected by the dike. [2] Garnets have been observed, under very analogous circumstances, in High Teesdale, by Professor Sedgwick, where they also occur in shale and limestone, altered by a basaltic dike. This discovery is most interesting, because garnets often abound in mica-schist, and we see in the instances above cited, that they did not previously exist in the shale and limestone, and that they have evidently been produced by heat in rocks in which the marks of stratification have not been
effaced.

Stirling Castle. -- To select another example: we find in the rock of Stirling Castle, a calcareous sandstone fractured and forcibly displaced by a mass of green-stone, which has evidently invaded the strata in a melted state. The sandstone has been indurated, and has assumed a texture approaching to hornstone near the junction. So also in Arthur's Seat and Salisbury Craig, near Edinburgh, a sandstone is seen to come in contact with greenstone, and to be converted into a jaspideous rock. [3]

Antrim. -- In the north of Ireland, in several parts of the county of Antrim, chalk, with flints, is traversed by basaltic dikes. The chalk is converted into granular marble near the basalt, the change sometimes extending eight or ten feet from the wall of the dike, being greatest at that point, and thence gradually decreasing till it becomes evanescent. 'The extreme effect,' says Dr. Berger, 'presents a dark brown crystalline limestone, the crystals running in flakes as large as those of coarse primitive limestone; the next state is saccharine, then fine- rained and arenaceous; a compact variety having a porcellanous aspect, and a bluish-grey colour succeeds; this, towards the outer edge, becomes yellowish-white, and insensibly graduates into the unaltered chalk. The flints in the altered chalk usually assume a grey yellowish colour.' [4] All traces of organic remains are effaced in that part of the limestone which is most crystalline.

As the carbonic acid has not been expelled, in this instance, from that part of the rock which must be supposed to have been melted, the change must have taken place under considerable pressure; for we know, by the experiments of Sir James Hall, that it would require the weight of about 1700 feet of sea-water, which would be equivalent to the pressure of a column of liquid lava 600 feet high, to prevent this acid from being given off.

Another of the dikes of the north-east of Ireland has converted a mass of red sandstone into hornstone. [5] By another, the slate-clay of the coal-measures has been indurated, and has assumed the character of flinty slate; [6] and in another place the slate-clay of the lias has been changed into flinty slate, which still retains numerous impressions of ammonites. [7] One of the greenstone dikes of the same country passes through a bed of coal, which it reduces to a cinder for the space of nine feet on each side. [8]

The secondary sandstones in Sky are converted into solid quartz in several places where they come in contact with veins or masses of trap; and a bed of quartz, says Dr. Macculloch, has been found near a mass of trap, among the coal-strata of Fife, which was in all probability a stratum of ordinary sandstone subsequently indurated by the action of heat. [9]

Alterations of strata in contact with granite. -- Having selected these from innumerable examples of mutations caused by volcanic dikes, we may next consider the changes produced by the contiguity of plutonic rocks. To some of these we have already adverted, when speaking of granite veins, and endeavouring to establish the igneous origin of granite. We mentioned that the main body of the Cornish granite sends forth veins through the killas of that country, [10] a coarse argillaceous schist, which is converted into hornblende- schist near the contact with the veins. These appearances are well seen at the junction of the granite and killas in St. Michael's l\fount, a small island nearly 300 feet high, situated in the bay, at the distance of about three miles from Penzance.

In the department of the Hautes Alpes, in France, near Vizille, M. Elie de Beaumont traced a black argillaceous limestone, charged with belemnites to within a few yards of a mass of granite. Here the limestone begins to put on a granular texture, but is extremely fine- grained. When nearer the junction it becomes grey and has a saccharoid structure. In another locality, near Champoleon, a granite composed of quartz, black mica, and rose-coloured felspar, is observed partly to overlie the secondary rocks, producing an alteration which extends for about thirty feet downwards, diminishing in the inferior beds which lie farthest from the granite. (See woodcut No. 90.) In the altered mass the argillaceous beds are hardened, the limestone is saccharoid, the grits quartzose, and in the midst of them is a thin layer of an imperfect granite. It is also an important circumstance, that near the point of contact both the granite and the secondary rocks become metalliferous, and contain nests and small veins of blende, galena, iron, and copper pyrites. The stratified rocks become harder and more crystalline, but the granite, on the contrary, softer and less perfectly crystallized near the junction. [11]

Image
No. 90: Junction of granite with Jurassic or oolite strata in the Alps, near Champoleon.

It will appear from sections described by M. Hugi, that some of the secondary beds of limestone and slate, which are in a similar manner overlaid by granite, have been altered into gneiss and mica-schist. [12] Some of these altered sedimentary formations are supposed, by M. Elie de Beaumont, to be of the age of the lias of England, and others to be even as modern as the jurassic or oolite formations.

We can scarcely doubt, in these cases, that the heat communicated by the granitic mass reduced the contiguous strata to semi-fusion, and that on cooling slowly the rock assumed a crystalline texture. The experiments of Gregory Watt prove, distinctly, that a rock need not be perfectly melted in order that a re-arrangement of its component particles should take place, and that a more crystalline texture should ensue. We may easily suppose, therefore, that all traces of shells and other organic remains may be destroyed, and that new chemical combinations may arise, without the mass being so fused as that the lines of stratification should be wholly obliterated.

In allusion to the passage from granite to gneiss before described, Dr. Macculloch remarks, that 'in numerous parts of Scotland, where the leading masses of gneiss are schistose, evenly stratified, and scarcely ever traversed by granite veins, they become contorted and irregular as they approach the granite; assuming also the granitic character, and becoming intersected by veins, numerous in proportion to the vicinity of the mass. The conclusion,' he adds, 'is obvious; the fluid granite has invaded the aqueous stratum as far as its influence could reach, and thus far has filled it with veins, disturbed its regularity and generated in it a new mineral character, often absolutely confounded with its own. And if the more remote beds, and those alternating with other rocks, are not thus affected, it is not only that it has acted less on those, but that, if it had equally affected them, they never could have existed, or would have been all granitic and venous gneiss. [13]

According to these views, gneiss and mica-schist may be nothing more than micaceous and argillaceous sandstones altered by heat, and certainly, in their mode of stratification and lamination, they correspond most exactly. Granular quartz may have been derived from siliceous sandstone, compact quartz from the same. Clay-slate may be altered shale, and shale appears to be clay which has been subjected to great pressure. Granular marble has probably originated in the form of ordinary limestone, having in many instances been replete with shells and corals now obliterated, while calcareous sands and marls have been changed into impure crystalline limestones.

Associated with the rocks termed primary we meet with anthracite, just as we find beds of coal in sedimentary formations, and we know that, in the vicinity of some trap dikes, coal is converted into anthracite. 'Hornblende schist,' says Dr. Macculloch, 'may at first have been mere clay, for clay or shale is found altered by trap into Lydian stone, a substance differing from hornblende-schist almost solely in compactness and uniformity of texture.' [14] 'In Shetland,' remarks the same author, 'argillaceous schist (or clay-slate), when in contact with granite, is sometimes converted into hornblende-schist, the schist becoming first siliceous, and ultimately, at the contact, hornblende-schist.' [15]

This theory, if confirmed by observation and experiment, may enable us to account for the high position in the series usually held by clay slate relatively to hornblende-schist, as also to gneiss and mica-schist, which so commonly alternate with hornblende-schist. .For we must suppose the heat which alters the strata to proceed, in almost all cases, from below upwards, and to act with greatest intensity on the inferior strata. If, therefore, several sets of argillaceous strata or shales be superimposed upon each other in a vertical series of beds in the same district, the lowest of these will be converted into hornblende-schist, while the uppermost may continue in the condition of clay- slate.

The term 'Hypogene' proposed for Primary. -- If our readers have followed us in the train of reasoning explained in this and the preceding chapter, they must already be convinced that the popular nomenclature of Geology, in reference to the so called' primary' rocks, is not only imperfect, but in a great degree founded on a false theory; inasmuch as some granites and granitic schists are of origin posterior to many secondary rocks. In other words, some primary formations can already be shown to be newer than many secondary groups -- a manifest contradiction in terms.

Yet granite and gneiss, and the families of stratified and unstratified rocks connected with each, belong to one great natural division of mineral masses, having certain characters in common, and it is therefore convenient that the class to which they belong should receive some common name-a name which must not be of chronological import, and must express, on the one hand, some peculiarity equally attributable to granite and gneiss (to the plutonic as well as the altered rocks), and which, on the other, must have reference to characters in which those rocks differ both from the volcanic and from the unaltered sedimentary strata. We propose the term 'hypogene' for this purpose, derived from Image subter, and Imagenascor, a word implying the theory that granite and gneiss are both nether-formed rocks, or rocks which have not assumed their present form and structure at the surface. It is true that gneiss and all stratified rocks must have been deposited originally at the surface, or on that part of the surface of the globe which is covered by water; but according to the views explained in this and the foregoing chapter, they could never have acquired their crystalline texture, unless acted upon by heat under pressure in those regions, and under those circumstances where the plutonic rocks are generated.

The term 'Metamorphic' proposed for stratified primary. -- We divide the hypogene rocks, then, into the unstratified, or plutonic, and the altered stratified. For these last the term 'metamorphic' (from Image trans, and Image form) may be used. The last-mentioned name need not, however, be often resorted to, because we may speak of hypogene strata, hypogene limestone, hypogene schist, and this appellation will suffice to distinguish the formations so designated from the plutonic rocks. By referring to the table (No. I.) at the close of this chapter, the reader will see the chronological relation which we conceive the two classes of hypogene rocks to bear to the strata of different ages.

No order of succession in hypogene formations. -- When we regard the tertiary and secondary formations simply as mineral masses uncharacterized by organic remains, we perceive an indefinite series of beds of limestone, clay, marl, siliceous sand, sandstone, coal, and other materials, alternating again and again without any fixed or determinate order of position. The same may be said of the hypogene formations, for in these a similar want of arrangement is manifest, if we compare those occurring in different countries. Gneiss, mica- schist, hornblende-schist, quartz rock, hypogene limestone, and the rest, have no invariable order of superposition, although, for reasons above explained, clay-slate must usually hold a superior position relatively to hornblende schist.

We do not deny, that in a particular mountain-chain, a chronological succession of hypogene formations may be recognized, for the same reason that in a country of limited extent there is an order of position in the secondary and tertiary rocks, limestone predominating in one part of the series, clay in another, siliceous sand in a third, and so of other compounds. It is probable that a similar prevalence of a regular order of arrangement in the hypogene series throughout certain districts, led the earlier geologists into a belief, that they should be able to fi x a definite order of succession for the various members of this great class throughout the world.

That expectation has not been realized; yet was it more reasonable than the doctrine of the universality of certain rocks which were admitted to be of sedimentary origin; for there is certainly a remarkable identity in the mineral character of the hypogene formations, both stratified and unstratified, in all countries; although the notion of a uniform order of succession in the different groups must be abandoned.

The student may, perhaps, object to the views above given of the relation of the sedimentary and metamorphic rocks, on the ground that there is frequently, indeed usually, an abrupt passage from one to the other. This phenomenon, however, admits of the same explanation as the fact, that the beds of lakes and seas are now frequently composed of hypogene rocks. In these localities the hypogene formations have been brought up to the surface and laid bare by denudation. New sedimentary strata are thrown down upon them, and in this manner the two classes of rocks, the aqueous and the hypogene, come into immediate contact, without any gradation from one to the other. As we suppose the plutonic and metamorphic rocks to have been uplifted at all periods in the earth's history, so as to have formed the bottom of the ocean and of lakes, by the same operations which have carried up marine strata to the summits of lofty mountains, we must suppose the juxtaposition of the two great orders of rocks now alluded to, to have been a necessary result of all former revolutions of the globe.

But occasionally a transition is observable from strata containing shells, and displaying an evident mechanical structure, to others which are partially altered, and from these again we sometimes pass insensibly into the hypogene series. Some of the argillaceous-schists in Cornwall are of this description, being undistinguishable from the hypogene schists of many countries, and yet exhibiting, in a few spots, faint traces of organic remains. In parts of Germany, also, there are schists which, from their chemical condition, are identical with hypogene-schists, yet are interstratified with greywacke, a rock probably modified by heat, but which contains casts of shells, and often displays unequivocal marks of being an aggregate of fragments of pre-existing rocks.

Those geologists who shrink from the theory, that all the hypogene strata, so beautifully compact and crystalline as they are, have once been in the state of the ordinary mud, clay, marl, sand, gravel, limestone, and other deposits now forming beneath the waters, resort, in their desire to escape from such conclusions, to the hypothesis, that chemical causes once acted with intense energy, and that by their influence more crystalline strata were precipitated; but this theory appears to us to be as mysterious and unphilosophical as the doctrine of a 'plastic virtue,' introduced by the earlier writers to explain the origin of fossil-shells and bones.

Relative age of the visible hypogene rocks. -- We shall now return to the subject already in part alluded to at the close of the last chapter-the relative age of the hypogene rocks as compared to the secondary. How far are they entitled in general to the appellation of 'primary,' in the sense of being anterior in age to the period of the carboniferous strata, in which last we include the greywacke and many of the rocks commonly called transition? It is undoubtedly true that we can rarely point out metamorphic or plutonic rocks which can be proved to have been formed in any secondary or tertiary period. We can, in some instances, demonstrate, as we have already shown, that there are granites of posterior origin to certain secondary strata, and that secondary strata have sometimes been converted into the metamorphic. But examples of such phenomena are rare, and their rarity is quite consistent with the theory, that the hypogene formations, both stratified and unstratified, have been always generated in equal quantities during periods of equal duration.

We conceive that the granite and gneiss, formed at periods more recent than the carboniferous era, are still for the most part concealed, and those portions which are visible can rarely be shown, by geological evidence, to have originated during secondary periods. It is very possible, for example, that considerable tracts of hypogene strata in the Alps may be altered oolite, altered lias, or altered secondary rocks inferior to the lias; but we can scarcely ever hope to substantiate the fact, because, whenever the change of texture is complete, no characters remain to afford us any insight into the probable age of the mass. Where granite happens to have intruded itself in such a manner as partially to overlie a mass of lias or other strata, as in the case before alluded to (diagram No. 90, p. 371), we may prove that fossilliferous strata have become gneiss, mica-schist, clay-slate, or granular marble; but if the action of the heat upon the strata had been more intense, the same inferences could not have been drawn. It might then have been supposed that no Alpine hypogene strata were newer than the carboniferous period.

The metamorphic strata of Scotland are certainly in great part older than the carboniferous, which are found incumbent upon them in an unaltered state; but it appears that secondary deposits as new, or newer than the lias, have come in contact, in the Western Islands, with granite, and have there assumed the hypogene texture.

A considerable source of difficulty and misapprehension, in regard to the antiquity of the metamorphic rocks, may arise from the circumstance of their having been deposited at one period, and having assumed their crystalline texture at another. Thus, for example, if an Eocene granite should invade the lias and superinduce a hypogene structure, to what period shall we refer the altered strata? Shall we say that they are metamorphic rocks of the Eocene or Liassic eras? They assumed their stratified form when the animals and plants of the lias flourished; they became metamorphic during the Eocene period. It would be preferable in such instances, we think, to consider them as hypogene strata of the Eocene period, or of that in which they were altered; yet it would rarely be possible to establish their true age. We should know the granite, to which the change of texture was due, to be newer than the lias which it penetrated; but there would rarely be any date to show that it might not have been injected at the close of the Liassic period, or at some much later era.

The metamorphic rocks must be the oldest, that is to say, they must lie at the bottom of each series of superimposed strata, because the influence of the volcanic heat proceeds from below upwards; but the hypogene strata of one country may be, and frequently are, of a very different age from those of another. The greater part, however, of the visible hypogene rocks are, we believe, more ancient than the carboniferous formations. In the latter, we frequently discover pebbles of hypo gene rocks, namely, granite, gneiss, mica-schist, and clay-slate; and the carboniferous rocks often rest unchanged upon the hypogene. According to our views of the operations of earthquakes, we ought not to expect plutonic and metamorphic rocks of the more modern eras to have reached the surface generally, for we must imagine many geological periods to elapse before a mass which has put on its particular form far below the level of the sea, can have been upraised and laid open to view above that level. Beds containing marine shells sometimes appear at the height of two or three miles in the principal mountain-chains, but they always belong to formations of considerable antiquity; still more should we be prepared to find the hypogene rocks now in sight to be of high relative antiquity, since, in order to be brought up to view, they must probably have risen from a position far inferior to the bottom of the ocean.

We shall endeavour to elucidate the cause of the great age of the plutonic and metamorphic rocks, now in sight, by a familiar illustration. Suppose two months to be the usual time required for passing from some tropical country to our island, and that an annual importation takes place of a certain tropical species of insect, the ordinary term of whose life is two months, and which can only be reared in the climate of that equatorial country. It is evident that no living individuals could ever be seen in England except in extreme old age. The young may come annually into the world in great numbers, but in order to see them, we must travel to lands near the equator.

In like manner, if the hypogene rocks can only originate at great depths in the regions of subterranean heat, and if it requires many geological epochs to raise them to the surface, they must be very ancient before they make their appearance in the superficial parts of the earth's crust. They may still be forming in every century, and they may have been produced in equal quantities during each successive geological period of equal duration; but in order to see them in a nascent state, slowly consolidating from a state of fusion, or semi- fusion, we must descend into the' fuelled entrails' of the earth, into the regions described by the poets, where for ages the land has

--ever burn'd
With solid, as the lake with liquid fire.


As the progress of decay and reproduction by aqueous agency is incessant on the surface of the continents, and in the bed of the ocean, while the hypogene rocks are generated below, or are rising gradually from the volcanic foci, thus there must ever be a remodelling of the earth's surface in the time intermediate between the origin of each set of plutonic and metamorphic rocks, and the protrusion of the same into the atmosphere or the ocean. Suppose the principal source of the Etnean lavas to lie at the depth of ten miles, we may easily conceive that before they can be uplifted to the day several distinct series of earthquakes must occur, and between each of these there might usually be one or more periods of tranquillity. The time required for so great a development of subterranean elevatory movements might well be protracted until the deposition of a series of sedimentary rocks, equal in extent to all our secondary and tertiary formations, had taken place. We conceive, therefore, that the relative age of the visible plutonic and metamorphic rocks, as compared to the unaltered sedimentary strata, must always be determined by the relations of two forces, -- the power which uplifts the hypogene rocks, and that aqueous agency which degrades and renovates the earth's surface; or, in other words, it must depend on the quantity of aqueous action which takes place between two periods, that when the heated and melted rocks are cooled and consolidated in the nether regions, and that when the same emerge to the day.

Volume of hypogene rocks supposed to have been formed since the Eocene period. -- If we were to indulge in speculations on the probable quantity of hypogene formations, both stratified and unstratified, which may have been formed beneath Europe and the European seas since the commencement of the Eocene period, we should conjecture, that the mass has equalled, if not exceeded in volume, the entire European continents. The grounds of this opinion will be understood by reference to what we have said of the causes which may have upheaved part of Sicily to a great height above the level of the sea since the beginning of the Newer Pliocene period. [16] If the theory which, in that instance, attributes the disturbance and upheaving of the superficial strata to the action of subterranean heat be deemed admissible, the same argument will apply with no less force to every other district, elevated or depressed, since the commencement of the tertiary period.

But we have shown, in our remarks on the map of Europe, in the second volume, that the conversion of sea into land, since the Eocene period, embraces an area equal to the greater part of Europe, and even those tracts which had in part emerged before the Eocene era, such as the Alps, Apennines, and other mountain-chains, have risen to the additional altitude of from 1000 to 4000 feet since that era. We have also stated the probability of a great amount of subsidence and the conversion of considerable portions of European land into sea during the same period-changes which may also be supposed to arise from the influence of subterranean heat.

From these premises we conclude, that the liquefaction and alteration of rocks by the operation of volcanic heat at successive periods, has extended over a subterranean space equal at least in area to the present European continent, and often through a portion of the earth's crust 4000 feet or more in thickness.

The principal effect of these volcanic operations in the nether regions, during the tertiary periods, or since the existing species began to flourish, has been to heave up to the surface hypogene formations of an age anterior to the carboniferous. We imagine that the repetition of another series of movements, of equal violence, might upraise the plutonic and metamorphic rocks of many of the secondary periods; and if the same force should still continue to act, the next convulsions might bring up the tertiary and recent hypogene rocks, by which time we imagine that nearly all the sedimentary strata now in sight would either have been destroyed by the action of water, or would have assumed the metamorphic structure, or would have been melted down into plutonic and volcanic rocks.

At the close of this chapter the reader will find a table of the chronological relations of the principal divisions of rocks according to the views above set forth. The sketch is confessedly imperfect, but it will elucidate our theory of the connexion which may exist between the hypogene rocks of different periods, and the alluvial, volcanic, and sedimentary formations. A second table is added, containing the names of some of the principal groups of sedimentary strata mentioned in this work, arranged in their order of superposition.

Concluding Remarks. -- In our history of the progress of geology, in the first volume, we stated that the opinion originally promulgated by Hutton, 'that the strata called primitive were mere altered sedimentary rocks,' was vehemently opposed for a time, the main objection to the theory being its supposed tendency to promote a belief in the past eternity of our planet. Previously the absence of animal and vegetable remains in the so-called primitive strata, had been appealed to, as proving that there had been a period when the planet was uninhabited by living beings, and when, as was also inferred, it was uninhabitable, and, therefore, probably in a nascent state.

The opposite doctrine, that the oldest visible strata might be the monuments of an antecedent period, when the animate world was already in existence, was declared to be equivalent to the assumption, that there never was a beginning to the present order of things. The unfairness of this charge was clearly pointed out by Playfair, who observed, 'that it was one thing to declare that we had not yet discovered the traces of a beginning, and another to deny that the earth ever had a beginning.'

We regret, however, to find that the bearing of our arguments in the first volume has been misunderstood in a similar manner, for we have been charged with endeavouring to establish the proposition, that ' the existing causes of change have operated with absolute uniformity from all eternity.' [17]

It is the more necessary to notice this misrepresentation of our views, as it has proceeded from a friendly critic whose theoretical opinions coincide in general with our own, but who has, in this instance, strangely misconceived the scope of our argument. With equal justice might an astronomer be accused of asserting, that the works of creation extend throughout infinite space, because he refuses to take for granted that the remotest stars now seen in the heavens are on the utmost verge of the material universe. Every improvement of the telescope has brought thousands of new worlds into view, and it would, therefore, be rash and unphilosophical to imagine that we already survey the whole extent of the vast scheme, or that it will ever be brought within the sphere of human observation.

But no argument can be drawn from such premises in favour of the infinity of the space that has been filled with worlds; and if the material universe has any limits, it then follows that it must occupy a minute and infinitessimal point in infinite space. So, if in tracing back the earth's history, we arrive at the monuments of events which may have happened millions of ages before our times, and if we still find no decided evidence of a commencement, yet the arguments from analogy in support of the probability of a beginning remain unshaken; and if the past duration of the earth be finite, then the aggregate of geological epochs, however numerous, must constitute a mere moment of the past, a mere infinitessimal portion of eternity.

It has been argued, that as the different. states of the earth's surface, and the different species by which it has been inhabited, have had each their origin, and many of them their termination, so the entire series may have commenced at a certain period. It has also been urged, that as we admit the creation of man to have occurred at a comparatively modern epoch as we concede the astonishing fact of the first introduction of a moral and intellectual being, so also we may conceive the first creation of the planet itself.

We are far from denying the weight of this reasoning from analogy; but although it may strengthen our conviction, that the present system of change has not gone on from eternity, it cannot warrant us in presuming that we shall be permitted to behold the signs of the earth's origin, or the evidences of the first introduction into it of organic beings.

In vain do we aspire to assign limits to the works of creation in space, whether we examine the starry heavens, or that world of minute animalcules which is revealed to us by the microscope. We are prepared, therefore, to find that in time also, the confines of the universe lie beyond the reach of mortal ken. But in whatever direction we pursue our researches, whether in time or space, we discover everywhere the clear proofs of a Creative Intelligence, and of His foresight, wisdom, and power.

As geologists, we learn that it is not only the present condition of the globe that has been suited to the accommodation of myriads of living creatures, but that many former states also have been equally adapted to the organization and habits of prior races of beings. The disposition of the seas, continents, and islands, and the climates have varied; so it appears that the species have been changed, and yet they have all been so modelled, on types analogous to those of existing plants and animals, as to indicate throughout a perfect harmony of design and unity of purpose. To assume that the evidence of the beginning or end of so vast a scheme lies within the reach of our philosophical inquiries, or even of our speculations, appears to us inconsistent with a just estimate of the relations which subsist between the finite powers of man and the attributes of an Infinite and Eternal Being.

_______________

Notes:

1. See above, p. 173.

2. Trans. of Cambridge Phil. Soc., vol. i. p. 406.

3. Illust. of Hutt. Theory, § 253 and 261. Dr. Macculloch, Geol. Trans., 1st series, vol. ii. p. 305.

4. Dr. Berger, Geol. Trans., 1st series, vol. iii. p. 172.

5. Rev. W. Conybeare, Geol. Trans., 1st series, vol. iii. p. 201.

6. Ibid., p. 205.

7. Ibid. p. 213, and Playfair, Illust. of Hutt. Theory, § 253.

8. Ibid., p. 206.

9. Syst. of Geol., vol. i. p. 206.

10. See diagram, No. 87.

11. Elie de Beaumont, Sur les Montagnes de l'Oisans, &c., Mem. de la Soc. d'Hist. Nat. de Paris, tome v.

12. Natur. Historische Alpenreise, Solcure, 1830.

13. Syst. of Geol., vol. ii. p. 145.

14. Ibid., vol. i. p. 210.

15. Ibid., p. 211.

16. See above, p. 107.

17. Quarterly Review, No. 86, Oct. 1830, p.464.
admin
Site Admin
 
Posts: 28480
Joined: Thu Aug 01, 2013 5:21 am

Re: Principles of Geology, by Charles Lyell

Postby admin » Fri Jul 17, 2015 3:11 am

RELATIVE AGES OF DIFFERENT FORMATIONS

Image
TABLE 1: Showing the Relations of the Alluvial, Aqueous, Volcanic, and
Hypogene Formations of different ages.


Image
TABLE 1 continued.

Image
DIAGRAM: Shewing the relative position which the Plutonic and Sedimentary Formations of different ages may occupy; (in illustration of TABLE I.)
No. 91.
4. Recent Strata.
3. Tertiary Strata.
2. Secondary strata.
1. Primary strata. *
1. Primary * plutonic.
2. Secondary plutonic.
3. Tertiary Plutonic.
4. Recent plutonic.


In the above diagram an attempt is made to shew the inverted order in which the sedimentary and plutonic formations may occur in the earth's crust; subterposition in the plutonic, like superposition in the sedimentary rocks, being for the most part characteristic of a newer age. By aid of this illustration, and what we have said in Chap. 25 and 26, the reader will comprehend why so large a portion of the plutonic rocks of later periods are concealed, and why the more ancient of this class have risen nearest to the surface, so as to have been denuded in some regions and exposed to view.

________________

* The primary formations here mentioned are those, whether stratified or unstratified, which are older than the carboniferous deposits.

Image
TABLE II. Showing the Order of Superposition, or Chronological Succession, of the principal Sedimentary Deposits or Groups of
Strata in Europe.


This Table is referred to in the Glossary, and includes the Secondary Formations alluded to in this Work, but not described in detail.

Image
TABLE II. continued.

Image
TABLE II. continued.

Image
TABLE II. continued.

Image
TABLE II. continued.
admin
Site Admin
 
Posts: 28480
Joined: Thu Aug 01, 2013 5:21 am

Re: Principles of Geology, by Charles Lyell

Postby admin » Fri Jul 17, 2015 3:20 am

INSTRUCTIONS FOR USING M. DESHAYES'S TABLES OF SHELLS

APPENDIX I.


THE object of these Tables is to give a list, not of the characteristic shells of the different tertiary formations, of which some figures are given in plates 1, 2, and 3, but to show the connexion of different periods by indicating the shells common to two or more periods, or common to some tertiary period and to the recent epoch.

The names also of a considerable number of species are given, as being found common to two or more formations of the same tertiary period. The localities where the fossil species are met with, and the known habitations of the living species, are also given.

No allusion is made to any secondary fossil shells; the word fossil, therefore, must always be understood to refer to tertiary formations. The number of species of recent and fossil shells which were examined and compared in constructing these tables amounted to 7,816, as follows:-

Image

Of these 3,036 fossil species, 426 were identified with individuals found among the 4,780 living species; 123 of them are only known in a fossil state, hut are mentioned as being common to more than one tertiary period; and 233 are enumerated by name, although not common to two tertiary periods, or to some tertiary period and the recent epoch, merely because they have been found in two or more formations of the same period. Thus the number of fossil species named in the tables amounts to 782, consisting of --

Image

A few will be found without specific names, because they have not yet been described or named by any authors.

The tables are continuous from p. 2 to p. 45, and the description of each species extends across two pages.

The following examples will best illustrate the object of the tables. If we take the first genus, Aspergillum (p. 2), we find that --

Column 1 gives the name of the genus.

Column 2 shows that four living species of the genus are known to M. Deshayes.

Column 3 that he has seen one fossil species.

Column 4 is left blank, because the single fossil species has not yet been identified with any living species.

Column 5 is also blank, because the fossil species is only known in one period or formation.

Column 6 is also blank, because the fossil species not having been identified with a living species, it was unnecessary to mention the habitation of any of the four living species.


The columns of the three periods are left blank, because the fossil species has not been found in more than one period. In the column of localities on the right of the right-hand page, in the subdivision headed Bordeaux, the figure 1 denotes that one species of fossil Aspergillum has been found in that locality.

To select another example: if we take the genus Solen (p. 2), we find that --

Column 2 shows that twenty-six living species of the genus are known to M. Deshayes.

Column 3 that he has seen nineteen fossil species of the genus.

Column 4 gives the name of the species Solen vagina, because that species is found both living and fossil.

Column 5 is left blank, because the names of those species only are placed in this column which have no living analogues, but are found in more than one period, or in more than on formation of the same period. [Thus, in the next line, Solen siliquarius has no living analogue, but it occurs in two formations of the Miocene period, viz. at Bordeaux and in Touraine.]

Column 6 shows that the living species of Solen vagina inhabits the European Ocean and Mediterranean.


The two asterisks in the column of the Pliocene period show that the species is found in two formations of that period, viz. in the Subapennine hills and the English crag.

The asterisk in the column of the Miocene period shows that this species is found in the basin of Vienna.

The word Baden in the next column indicates that the species is also found fossil in that locality.

The column of the Eocene period is blank, because the shell has not been found in any formation belonging to that period.

The figures in the column of localities will be understood by what we said above. In summing up these figures it will be found that they amount to thirty-one, whereas it is stated, in the third column of the left-hand page, that only nineteen fossil species have been found. The disagreement arises from this-that the same species occur in more than one locality, and thus come to be counted more than once in the column of localities.

N. B. In some cases, before the totals of the species in the columns of localities can tally with the figures in the third column, the species enumerated in the supplementary table of localities, p. 46, must be taken into account.

A note of interrogation added to the asterisk (*?) indicates a doubt as to the correct identification of the shell, either because the shell is a variety which has a somewhat distant analogy to the recognized type of the species, or because the specimen examined was in rather an imperfect state.

The specific names of the tertiary fossil shells which have been found by M. Deshayes to belong to one period only, and for which he has not yet discovered any living analogues, are not given, as their enumeration would have required more space than could be allotted to such a subject in a treatise on Geology; but their aggregate number is included in the subdivisions of the column in the right-hand page headed No. of species in each genus in the following localities,' and in the supplementary table, p.46.

APPENDIX I.

TABLES OF FOSSIL SHELLS, BY MONSR G. P. DESHAYES, Member of the Geological Society of Paris, &c.


N.B. For a full explanation of the object of these Tables, and instructions as to the manner of using them, see the preceding four pages.

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

SUPPLEMENTARY TABLE

Containing Localities for which there was not sufficient space in the preceding tables.

Image
admin
Site Admin
 
Posts: 28480
Joined: Thu Aug 01, 2013 5:21 am

Re: Principles of Geology, by Charles Lyell

Postby admin » Fri Jul 17, 2015 3:36 am

GENERAL RESULTS

DEDUCED PROM A COMPARISON OF THE SPECIES EXAMINED IN COMPILING THE FOREGOING TABLES.

PLIOCENE PERIOD.

Italy, Sicily, the Morea, Perpignan, and the English Crag. The fossils of Perpignan and the Morea are, with the exception of three or four species, the same as those of Italy.

Image

Image

Image

Image

The number of living analogues is 350, which is in the proportion of 49 in 100.

MIOCENE PERIOD.

Bordeaux, Dax, Touraine, Turin, Baden, Vienna, Moravia, Hungary, Cracovia, Volhynia, Podolia, Transylvania, Angers, and Ronca. [2]

The species of Moravia, Hungary, Cracovia, Volhynia, Podolia, and Transylvania, are the same, with a very few exceptions, as those of Vienna and Baden.

Image

Image

The number of living analogues is 176, which is in the proportion of rather less than 18 in 100; the number of fossil analogues, after subtracting those which pass from the Miocene into both the Pliocene and Eocene epochs, is 168, which is very nearly in the same proportion.

The species which pass from the Miocene into the Pliocene period are in number 196, of which 114 are living, and 82 fossil, which is very nearly in the proportion of 20 in 100 of the total number of species of the latter epoch. Thus it is remarkable that there are 18 in 100 living analogues, 18 in 100 of analogous fossil species, and that 20 in 100 of these species pass from the Miocene to the Pliocene epoch.

The 114 living species, and the 82 fossil ones, which are common to the Miocene and Pliocene periods, are distributed, in the last- mentioned epoch, in the following manner: --

Image

The preceding distribution of species will show that Italy is represented in the Miocene period by 181 species, Sicily by 69, and the Crag by 20.

EOCENE PERIOD.

Paris, London, Valognes, Belgium, Castelgomberto, and Pauliac.

A small number of species only have been examined from Belgium, Pauliac, and Castelgomberto, but which agreed, with few exceptions, with species of the Paris basin. So also in regard to Valognes.

Image

The number of fossils of this period identified with living species is 42, which is to 1238 in the proportion of 31 in 100. The number of fossil species which pass from the Eocene into the two other periods is 46. that is to say. in nearly the same proportion as the living analogues. Among the fossil species, four only are common to the three epochs, which are the following: --

1 Dentalium coarctatum.
2 Tornatella inflata.
3 Bulimus terebellatus.
4 Corbula complanata.

The 42 other fossil species, which go no farther than the Miocene epoch, are distributed in the following manner: --

Image

Of the 42 living species, the following 13 are common to the three epochs, --

1 Dentalium entalis,
2 ---------- strangulatum,
3 Fissurella graeca,
4 Bulla lignaria,
5 Rissoa cochlearella,
6 Murex fistulosus,
7 Murex tubifer,
8 Polymorphina gibba,
9 Triloculina oblonga,
10 Lucina divaricata,
11 ---------- gibbosula,
12 Isocardia cor,
13 Nucula margaritacea.

Of the other species, 7 go no farther than the Miocene epoch, and are distributed in the following manner, --

Image

Total number of species in the three periods, --

Image

From the above lists it will appear that there are 17 species which are common to the three epochs. and which may therefore be said to characterise the entire tertiary formations of Europe. Thirteen of them are species still living, while four are only known as fossil. There is not a single species common to the Pliocene and Eocene epochs which is not also found in the Miocene.

GEOGRAPHICAL DISTRIBUTION OF THE LIV1NG SPECIES WHICH HAVE THEIR FOSSIL ANALOGUES.

Image

Image

Image

______________

Notes:

1. The statement that there are only 4 species common to Italy and the Crag, may seem inconsistent with the fact that 18 are common to those places and to Sicily; but the reader will understand that there are only 4 species which are common to Italy and the Crag, and which are not also common to some other Pliocene locality. The same remark is applicable to similar statements in the sequel.

2. Ronca may very probably belong to the Eocene epoch; but in this, as in respect to a few other localities mentioned in the tables, the number of analogues is too small to lead to certain conclusions.

3. Image
There are at Bordeaux: 446 species
and at Dax : 473
making a total of: 919

but from the great number of species common to the two localities there are, in reality, only 594 species, as above mentioned.
admin
Site Admin
 
Posts: 28480
Joined: Thu Aug 01, 2013 5:21 am

Re: Principles of Geology, by Charles Lyell

Postby admin » Fri Jul 17, 2015 3:38 am

FOSSIL SHELLS COLLECTED BY THE AUTHOR FROM VARIOUS LOCALITIES OF THE NEWER PLIOCENE FORMATION IN SICILY; NAMED BY M. DESHAYES.

N. B. Those which are marked with an asterisk in this and the following lists are unknown as recent.

FOSSIL SHELLS FROM THE FLANKS OF ETNA, IMMEDIATELY ABOVE THE BAY OF TREZZA.

In clay and volcanic tuff. (See p. 79.)


Mactra triangula, Broc.
Corbula nucleus.
Astarte, unnamed.
Astarte ditto.
Venus Brongniarti, Payraudeau.
Venus radiata.
Venus species doubtful.
Cytherea exoleta.
Cytherea lincta.
Cardium edule.
Cardium sulcatum.
Arca antiquata, Lamk.
Arca barbata, Lamk.
Pectunculus glycimeris.
Pectunculus pilosus.
Nucula, new species.
Nucula margaritacea.
Chama unicornis.
Pecten ornatus.
Pecten an, new species?
Pecten Bruei, Payr.
Pecten opercularis.
Pecten unicolor.
Pecten Jacobaeus.
Ostrea edulis.
Anomia ephippium.
Dentalium entalis.
Dentalium *new species.
Centalium strangulatum, Desh.
Dentalium novem costatum.
Pileopsis Ungarica.
Calyptraea Chinensis.
Natica millepunctata.
Natica Dillwynii, Payr.
Natica Guillemini, Payr.
Natica glaucina.
Trochus magus.
Trochus conulus.
Trochus Adansoni, Payr.
Turbo rugosus.
Monodonta Viellotii, Payr.
Turritella terebra, Broc.
Cerithium sulcatum.
Pleurotoma, new species.
Cancellaria cancellata.
Fusus, new species.
Fusus new species.
Fusus craticulatus, Blainv.
Fusus strigosus.
Fusus lignarius.
Murex trunculus.
Murex Brandaris.
Murex erinaceus.
Triton an pileare?
Rostellaria pes pelicani.
Cassidaria echinophora.
Buccinum musivum, Broc.
Buccinum mutabile.
Buccinum macolosum.
Buccinum unnamed.
Buccinum Calmelii.
Buccinum semistriatum.
Colombella rustica.
Mitra lutescens.
Conus Mediterraneus

VILLASMONDE. (See p. 65.)

Mactralactaea.
Corbula nucleus.
Pecten opercularis.
Dentalium novem costatum.
Natica glaucina.
Natica canrena.
Rostellaria pes pelicani

MILITELLO. (V. DI NOTO.) (See p. 65.)

Cytherea chione?
Cardium edule.
Arca antiquata.
Pecten Jacobaeus.
Pecten varius.
Pecten opercularis.
Ostrea edulis.
* Dentalium, new species.
Buccinum prismaticum?
An Turbo rugosus???

GIRGENTI. -- (In limestone and clay. -- See p. 65.)

Corbula nucleus.
Mactra triangula? Broc.
Pectunculus pilosus.
Modiola, species doubtful.
Pecten Jacobaeus.
Pecten opercularis.
Dentalium entalis.
Natica millepunctata.
* Turritella tornata.
*Buccinum semistriatum.

SYRACUSE. (See p. 67.)

Thracia pubescens.
* Tellina?
Cardium sulcatum.
Cardium edule.
Cardium echinatum.
Isocardia cor.
Arca antiquata.
Pectunculus pilosus.
Pectunculus glycimeris.
Pecten, an nodosus?
Pecten Jacobaeus.
Pecten Audouini, Payr.
Pecten opercularis.
Pecten coarctatus, Broc.
Pecten varius.
Ostrea edulis.
* Dentalium, new species.
Dentalium strangulatum, Desh.
Dentalium sexangulare, Broc.
Haliotis tuberculata.
Trochus conulus.
Turritella terebra.
Murex trunculus?
* Buccinum semistriatum.
Cypraea rufa.
Conus Mediterraneus??

CALTANISETTA. -- (In clay and yellow sand. -- See p. 67.)

Lucina lactea?
Venus multilamella.
Cardium echinatum.
Cardium edule.
Arca antiquata.
Pecten Jacobaeus.
Ostrea edulis.
*Dentalium, new species.
Dentalium fossile.
Dentalium sexangulare.
Natica Guillemini, Payr.
Natica millepunctata.
Turritella subangulata, Broc.
* Turritella tornata, Broc.
Turritella terebra.
Cerithium vulgatum.
Fusus lignarius.
Rostellaria pes pelicani.
* Buccinum semistriatum.
Mitra lutescens.

CALTAGIRONE. (See p. 67.)

Mactra triangula, Broc.
Amphidesma, new species.
Corbula nucleus.
Psammobia angulata (Tellina, Lin)
Cytherea lincta.
Venus multilamella.
Cardita sulcata, Brug.
Cardita squamosa.
Cardium echinatum.
Area antiquata.
* Nucula Italica, Def.
Pecten opercularis.
Pecten Bruei, Payr.
Dentalium, new species.
Dentalium entalis.
Dentalium novem costatum.
Fissurella costaria, Desh.
Calyptraea chinensis.
Bulla lignaria.
Natica canrena.
Natica Dilwynii, Payr.
Natica Valenciennesii, Payr.
Natica Guillemini, Payr.
Scalaria tenuicostata, Mich.
Turritella terebra.
Cerithium Latreillei, Payr.
* Pleurotoma, new species.
Pleurotoma vulpecula, Broc.
Pleurotoma craticulata, Broc.
Fusus craticulatus, Blain.
Fusus lignarius.
Fusus rostratus.
Murex Brandaris.
Rostellaria pes pelicani.
* Buccinum semistriatum.
Buccinum mutabile.
Buccinum prismaticum, Broc.
* Buccinum turbinellus, Broc.
Mitra lutescens.
Cypraea oryza, Duclos.

CASTROGIOVANNI. (See p. 67.)

Lucina lactea.
* Nucula Italica, Def.
Pecten Jacobaeus.
Pecten opercularis.
Natica Guillemini, Payr.

VIZZINI.

Murex Brandaris.

PIAZZA.

Ostrea edulis.

VAL DI NOTO.

Pectunculus glycimeris.
Pecten opercularis.

PALERMO. -- (In limestone and clay. -- See p. 65.)

*Clavagella bacillaris, Desh.
Solen coarctatus, Broc.
Panopea Aldrovandi.
Thracia corbuloides, Desh.
Thracia pubescens, Desh.
Lutraria solenoides.
Corbula nucleus.
Tellina Donacina.
Tellina new species.
Lucina radula.
Lucia new species, a lupinus? Broc.
Lucia lactea.
Astarte, new species, an incrassata?
Astarte new species.
Cytherea rugosa, Broc.
Cytherea exoleta.
Cytherea Chione.
Venus radiata, Broc.
Venus species doubtful
Cardita Squamosa.
Cyprina Islandicoides.
Cardium sulcatum.
Cardium edule.
Cardium echinatum.
Cardium Deshayesii, Payr.
Isocardia cor.
Area antiquata.
Pectunculus pilosus.
Nucula, new species.
Nucula margaritacea.
Chama gryphoides?
Cham unicornis.
Pecten ornatus.
Pecten coarctatus, Broc.
Pecten an, new species.
Pecten opercularis.
Pecten new species.
Pecten Jacobaeus.
Pecten varius??
Pecten pleuronectes.
Ostrea cornucopiae ?
Ostrea edulis.
Ostrea Virginica.
Ostrea hippopus.
Terebratula truncata.
* Terebratula ampulla.
* Dentalium, new species.
* Dentalium fossile, Lin. Var.
Dentalium strangulatum, Desh.
Patella bonnardii, Payr.
Emarginula curvirostris, Desh.
Fissurella, species doubtful.
Fissurella Graeca.
Pileopsis Ungarica.
Bulla lignaria.
Auricula buccinea.
Natica millepunctata.
Natica Guillemini, Payr.
Natica. Canrena.
Natica Valenciennesii, Payr.
Scalaria communis.
Scalaria pseudo scalaris.
Solarium stramineum?
Trochus magus.
Trochus agglutinans.
Trochus cingulatus, Broc.
Trochus Adansoni, Payr.
Trochus conulus.
Trochus cinereus.
Turbo rugosus.
Turritella terebra.
Cerithium tricinctum.
* Cerithium margaritaceum.
* Cerithium new species.
Pleurotoma Cordieri.
Pleurotoma Caumarmondi, Mich.
Pleurotoma new species.
Fasciolaria tarentina.
Fusus sinistrorsus, Desh.
Fusus strigosus.
Fusus rostratus.
* Fusus clavatus.
Fusus craticulatus.
* Fusus new species.
Fusus lignarius.
Ranella gigantea.
* Ranella laevigata.
Murex Brandaris.
Murex trunculus.
Triton unifilosum, Bon.
Rostellaria pes pelicani.
Cassidaria echinophora.
Cassis saburon.
Dolium pomum.
Buccinum prismaticum, Broc.
Buccinum new species.
Buccinum new species.
* Buccinum semistriatum.
Buccinum new species.
Buccinum mutabile.
Conus Mediterraneus.

2. -- FOSSIL SHELLS COLLECTED BY THE AUTHOR IN ISCHIA, AND NAMED BY M. DESHAYES. (See p. 126.)

Solen coarctatus, Broc.
Lucina lupinus, Broc.
Venus radiata, Broc.
Venus verrucosa.
Cardium sulcatum.
Cardium edule.
Pectunculus violacescens.
Arca, new species, An area quoyi? Payr.
Nucula margaritacea.
Pecten varius.
Pecten Jacobaeus.
Pecten Dumasii, Payr.
Pecten opercularis.
Dentalium novem costatum.
Melania Cambessedesii, Payr.
Natica Guillemini, Payr.
Natica Valenciennesii? Payr.
Trochus magus.
Trochus conuloides.
Trochus new species.
Turritella terebra.
Cerithium Latreillei, Payr.
Cerithium new species.
Cerithium vulgatum.
Cerithium doliolum, Broc.
Rostellaria pes pelicani.
Buccinum prismaticum, Broc.
Cypraea lurida.

The four following shells have since been sent to me from Ischia. They are all of recent species;-

Pectunculus pilosus.
Natica glaucina?
Trochus crenulatus.
Turritella duplicata.

FOSSIL SHELLS FROM THE WESTERN BORDERS OF THE RED SEA, COLLECTED BY MR. JAMES BURTON, COMMUNICATED BY G. B. GREENOUGH, ESQ., P.G.S.

Lutraria solenoides?
Lutraria plicatella??
Mactra stultorum?
Corbula.
Psammobia.
Tellina lingua felis.
Tellina rugosa.
Tellina virgata.
Tellina rostrata.
Lucina globosa.
Cyprina.
Cytherea tigerina.
Cytherea picta.
Cytherea castrensis.
Cytherea erycina.
Cytherea scripta?
Venus geographica.
Venus reticulata.
Venus ovata??
Venus paphia.
Cardium rugosum.
Cardium AEolicum?
Cardium retusum.
Cardita turgida.
Cardita calyculata.
Cypricardia.
Chama lazarus.
Tridacna squamosa.
Arca scapha.
Arca antiquata.
Arca Noae.
Pectunculus pectiniformis.
Pecten maximus.
Pecten pes felis.
Spondylus gaderopus.
Parmophorus elegans.
Fissurella Graeca.
Bulla ampulla.
Bulla solida.
Helix desertum.
Nerita.
Natica melanostoma.
Natica mamillaris.
Natica mamilla.
Natica Graeca.
Natica alba.
Haliotis tuberculata?
Haliotis striata?
Tornatella.
Pyramidella.
Solarium perspectivum.
Trochus maculatus.
Trochus virgatus.
Trochus Mauritianus.
Monodonta tectum.
Monodonta Pharaonis.
Monodonta AEgyptica.
Turbo chrysostomus.
Turbo petholatus.
Turritella
Cerithium nodulosum.
Cerithium sulcatum.
Cerithium virgatus.
Pleurotoma virgo.
Turbinella lineolata.
Cancellaria contabulata.
Fasciolaria trapezium.
Pyrula abbreviata.
Pyrula rapa.
Pyrula citrina.
Pyrula reticulata.
Pyrula francolinus.
Ranella granifera.
Ranella crumena.
Murex crassispina.
Murex scorpio.
Triton variegatum.
Triton lampas.
Triton pileare.
Triton maculosum.
Strombus gigas (young).
Strombus bituberculatus.
Strombus lineolatus.
Strombus gibberulus.
Strombus terebellatus.
Cassis vibex.
Cassis saburon.
Cassis erinaceus.
Ricinula arachnoides.
Dolium perdix.
Dolium pomum.
Buccinum coronatum.
Buccinum arcularia.
Buccinum senticosum.
Terebra crenulata.
Terebra subulata.
Terebra myosurus.
Terebra maculata.
Terebra duplicata.
Colombella turturina?
Mitra striatula.
Mitra coronata?
Cypraea mappa.
Cypraea Arabica.
Cypraea talpa.
Cypraea caurica.
Cypraea vitellus.
Cypraea erosa.
Cypraea carneola.
Cypraea turdus?
Cypraea lurida?
Cypraea flaveola?
Cypraea nucleus.
Cypraea stercus muscarum?
Cypraea caput serpentis?
Ancillaria.
Oliva erythrostoma.
Conus arenatus.
Conus generalis.
Conus literatus?
Conus betulinus.
Conus striatus.
Conus episcopus.
Conus tessellatus.
Conus textile.
Conus nussatella.
Conus clavus.
Conus terebra??
Conus capitaneus.
Terebellum subulatum.

The above shells were named by Mr. GRAY, F.R.S., and Mr. Frembley.

FOSSIL SHELLS COLLECTED BY THE AUTHOR FROM THE LOESS OF THE VALLEY OF THE RHINE. (See p. 151.)

Helix obvoluta, Drap.
Helix ericetorum, ib.
Helix carthusianella, ib.
Helix plebeium, ib.
Helix pomatia.
Helix nemoralis, ih.
Helix fruticum, Drap.
Helix arbustorum.
Helix striata, Drap.
Succinea elongata.
Cyclas palustris, Drap.
Cyclas lacustris, ib.
Valvata piscinalis.
Limnea ovata, Drap.
Paludina impura.

SIENNA. (See pp. 160 and 163.)

Serpula arenaria.
Serpula ditto, var.
* Serpula new species.
* Serpula glomerata.
Mactra triangula.
Tellina complanata.
* Cytheraea rugosa, Broc.
Cardita intermedia.
* Cardita new species.
Cardium edule.
Area antiquata.
Pectunculus pilosus.
Pectunculus nummarius.
* Pectunculus auritus.
Nucula margaritacea.
Pecten Jacobaeus.
Pecten opercularis.
* Pecten striatus?
* Pecten laticostatus.
Ostrea edulis, Lin.
Ostrea edulis? junior.
* Ostrea (nobis incognita).
Dentalium sexangulare.
* Dentalium fossile.
Auricula buccinea, Desh.
Melanopsis buccinoides.
Natica glaucina.
Natica punctata.
Natica Marochiensis.
Trochus fermonii, Payr.
* Trochus new species, with its colour.
Turbo rugosus.
Turritella terebra.
* Turritella imbricataria, Broc.
Turritella subangulata.
* Turritella tornata.
* Turritella varicosa.
Cerithium vulgatum.
Cerithium doliolum.
* Cerithium tricinctum.
* Cerithium new species.
* Cerithium new species.
* Pleurotoma cataphracta.
* Pleurotoma interrupta, Broc.
* Pleurotoma oblonga, Broc.
* Pleurotoma rotata, Broc.
* Pleurotoma reticulata, Broc.
* Pleurotoma textilis, Broc.
* Pleurotoma turricula, Broc.
* Pleurotoma dimidiata, Broc. (dentata, Lamk.)
* Pleurotoma dimidiata, var.
Cancellaria cancellata.
* Cancellaria varicosa.
* Cancellaria Lyrata.
Fusus lignarius
* Fusus mitraeformis.
Fusus subulatus.
* Fusus longiroster.
* Fusus thiara, Broc.
* Ranella bimarginata.
Murex cornutus, var.
Murex tubifer.
* Murex horridus.
* Murex spirispina.
Murex pomum.
* Murex bracteatus, Broc.
* Murex new species.
Triton unifilosus, Bonelli.
* Triton reticularis, Broc.
* Triton new species.
Rostellaria pes pelicani.
* Strombus Bonelli, Brong.
Cassis saburon.
Buccinum clathratum? Broc.
* Buccinum serratum, Broc.
* Buccinum costulatum.
* Buccinum gibbosulum.
* Terebra plicaria.
* Terebra duplicata.
* Mitra pyramidella, Broc.
* Mitra scrobiculata.
Marginella cypraeola.
* Conus antediluvianus, Broc.
* Conus ponderosus.
* Conus mercator.
* Conus pyrula, Broc.
* Conus betulinoides.
* Conus virginalis.

SECONDARY FOSSIL SHELLS.

FOSSIL SHELLS COMMON TO THE MAESTRICHT BEDS AND THE WHITE CHALK; COMMUNICATED BY M. DESHAYES. (See p. 325.)


Catillus (Inoceramus) Cuvieri? (specimens imperfect.)
Plagiostoma spinosa.
Plagiostoma Hoperi.
Pecten fragilissimus.
Ostrea vesicularis.
Ostrea carinata.
Crania Parisiensis.
Terebratula octoplicata.
Terebratula carnea.
Terebratula pumilus (magus, Sow.)
Terebratula Defrancii.
Belemnites mucronatus.

FOSSIL SHELLS COMMON TO THE MAESTRICHT BEDS AND THE UPPER GREEN-SAND; COMMUNICATED BY M. DESHAYES. (See p. 325.)

Plagiostoma spinosa.
Ostrea vesicularis.
Ostrea carinata.
Belemnites mucronatus.
Baculites Faujasii.
admin
Site Admin
 
Posts: 28480
Joined: Thu Aug 01, 2013 5:21 am

Re: Principles of Geology, by Charles Lyell

Postby admin » Fri Jul 17, 2015 4:09 am

GLOSSARY

Of Geological and other Scientific Terms used in this Work.

Several of the Author's friends, who had read the first and second volumes of the Principles of Geology, having met with difficulties from their previous un acquaintance with the technical terms used in Geology and Natural History, suggested to him that a Glossary of those words would render his work much more accessible to general readers. The Author willingly complied with this suggestion, but finding that his own familiarity with the subject made him not a very competent judge of the terms that required explanation, he applied to the friends above alluded to for their assistance, and from lists of words supplied by them, the following Glossary has been constructed. It will be obvious to men of science, that in order to attain the object in view, it was necessary to employ illustrations and language as familiar as possible to the general reader.

ACEPHALOUS. The Acephala are that division of molluscous animals which, like the oyster and scallop, are without heads. The class Acephala of Cuvier comprehends many genera of bivalve shells, and a few genera of mollusca which are devoid of shells. Etym., a, a, without, and , cephale, the head.

ALGAE. An order or division of the cryptogamic class of plants. The whole of the sea-weeds are comprehended under this division, and the application of the term in this work is to marine plants. Etym., Alga, sea-weed.

ALUM-STONE, ALUMEN, ALUMINOUS. Alum is the base of pure clay, and strata of clay are often met with containing much iron- pyrites. When the latter substance decomposes, sulphuric acid is produced, which unites with the aluminous earth of the clay to form sulphate of alumine, or common alum. Where manufactories are established for obtaining the alum, the indurated beds of clay employed are called Alum-stone.

ALLUVIAL. The adjective of alluvium, which see.

ALLUVION. Synonymous with alluvium, which see.

ALLUVIUM. Earth, sand, gravel, stones, and other transported matter which has been washed away and thrown down by rivers, floods, or other causes, upon land not permanently submerged beneath the waters of lakes or seas. Etym., Alluo, to wash upon. For a further explanation of the term, as used in this work, see vol. ii. chap. xiv., and vol. iii. p. 145.

AMMONITE. An extinct and very numerous genus of the order of molluscous animals, called Cephalopoda, allied to the modern genus Nautilus. which inhabited a chambered shell, curved like a coiled snake. Species of it are found in all geological periods of the secondary strata; but they have not yet been seen in the tertiary beds. They are named from their resemblance to the horns on the statues of Jupiter Ammon.

AMORPHOUS. Bodies devoid of regular form. Etym., a, a, without, and morphe, form.

AMYGDALOID. One of the forms of the Trap-rocks, in which agates and simple minerals appear to be scattered like almonds in a cake. Etym., amygdala, an almond.

ANALCIME. A simple mineral of the Zeolite family, of frequent occurrence in the trap-rocks.

ANALOGUE. A body that resembles or corresponds with another body. A recent shell of the same species as a fossil-shell, is the analogue of the latter.

ANOPLOTHERE, ANOPLOTHERIUM. A fossil extinct quadruped belonging to the order Pachydermata, resembling a pig. It has received its name because the animal must have been singularly wanting in means of defence, from the form of its teeth and the absence of claws, hoofs, and horns. Etym., anoplos, unarmed, and therion, a wild beast.

ANTAGONIST POWERS. Two powers in nature, the action of the one counteracting that of the other, by which a kind of equilibrium or balance is maintained, and the destructive effect prevented that would be produced by one operating without a check.

ANTENNAE. The articulated horns with which the heads of insects are invariably furnished.

ANTHRACITE. A shining .substance like black-lead; a species of mineral charcoal. Etym., anthrax, coal.

ANTHRACOTHERIUM. A name given to an extinct quadruped, supposed to belong to the Pachydermata, the bones of which were found in lignite and coal of the tertiary strata. Etym., anthrax, coal, and therion, wild beast.

ANTHROPOMORPHOUS. Having a form resembling the human. Etym., anthropos, a man, and morphe, form.

ANTICLINAL AXIS. If a range of hills, or a valley, be composed of strata, which on the two sides dip in opposite directions, the imaginary line that lies between them, towards which the strata on each side rise, is called the anticlinal axis. In a row of houses with steep roofs facing the south, the slates represent inclined strata dipping north and south, and the ridge is an east and west anticlinal axis. For a farther explanation, with a diagram, see vol. iii. p. 293.

ANTISEPTIC. Substances which prevent corruption in animal and vegetable matter, as common salt does, are said to be antiseptic. Etym., against, and sepo, to putrefy.

ARENACEOUS. Sandy. Etym., Arena, sand.

ARGILLACEOUS. Clayey, composed of clay. Etym., Argilla, clay.

ARRAGONITE. A simple mineral, a variety of carbonate of lime, so called from having been first found in Arragon, in Spain.

AUGITE. A simple mineral of a dark green, or black colour, which forms a constituent part of many varieties of volcanic rocks.

AVALANCHES. Masses of snow which, being detached from great heights in the Alps, acquire enormous bulk by fresh accumulations as they descend; and when they fall into the valleys below often cause great destruction. They are also called lavanges, and lavanches, in the dialects of Switzerland.

BASALT. One of the most common varieties of the Trap-rocks. It is a dark green or black stone, composed of augite and felspar, very compact in texture, and of considerable hardness, often found in regular pillars of three or more sides, called basaltic columns. Very remarkable examples of this kind of rock are seen at the Giant's Causeway, in Ireland, and at Fingal's Cave, in the island of Staffa, one of the Hebrides. The term is used by Pliny, and is said to come from basal, an AEthiopian word signifying iron, not an improbable derivation, inasmuch as the rock often contains much iron, and as many of the figures of the Egyptian temples are formed of basalt.

'BASIN' of Paris, 'BASIN' of London. Deposits lying in a great hollow or trough surrounded by low hills or high land, sometimes used in geology almost synonymously with 'formation.'

BELEMNITE. An extinct genus of the order of molluscous animals called Cephalopoda, that inhabited a long, straight, and chambered conical shell. Etym., belemnon, a dart.

BITUMEN. Mineral pitch, of which the tar-like substance which is often seen to ooze out of the Newcastle coal when on the fire, and which makes it cake, is a good example. Etym., Bitumen, pitch.

BITUMINOUS SHALE. An argillaceous shale, much impregnated with bitumen, which is very common in the coal measures.

BLENDE. A metallic ore, a compound of the metal zinc with sulphur. It is often found in brown shining crystals, hence its name among the German miners, from the word blenden, to dazzle.

BLUFFS. High banks presenting a precipitous front to the sea or a river. A term used in the United States of North America.

BOTRYOIDAL. Resembling a bunch of grapes. Etym., botrys, a bunch of grapes, and eidos, form.

BOWLDERS. A provincial term for large rounded blocks of stone lying on the surface of the ground, or sometimes imbedded in loose soil, different in composition from the rocks in their vicinity, and which have been therefore transported from a distance.

BRECCIA. A rock composed of angular fragments connected together by lime or other mineral substance. An Italian term.

CALC SINTER. A German name for the deposits from springs holding carbonate of lime in solution-petrifying springs. Etym., Kalk, lime, sintern, to drop.

CALCAIRE GROSSIER. An extensive stratum, or rather series of strata, belonging to the Eocene tertiary period, originally found in, and specially belonging to, the Paris Basin. See Table II. E, p. 390. Etym., Calcaire, limestone, and grossier, coarse.

CALCAREOUS ROCK. Limestone. Eiym., Calx, lime.

CALCEDONY. A siliceous simple mineral, uncrystallized. Agates are partly composed of calcedony.

CARBON. An undecomposed inflammable substance, one of the simple elementary bodies. Charcoal is almost entirely composed of it. Etym., Carbo, coal.

CARBONATE of LIME. Lime combines with great avidity with carbonic acid, a gaseous acid only obtained fluid when united with water,-and all combinations of it with other substances are called Carbonates. All limestones are carbonates of lime, and quick lime is obtained by driving off the carbonic acid by heat.

CARBONATED SPRINGS. Springs of water, containing carbonic acid gas. They are very common, especially in volcanic countries, and sometimes contain so much gas, that if a little sugar be thrown into the water it effervesces like soda-water.

CARBONIC ACID GAS. A natural gas which often issues from the ground, especially in volcanic countries. Etym., Carbo, coal, because the gas is obtained by the slow burning of charcoal.

CARBONIFEROUS. A term usually applied, in a technical sense, to the lowest group of strata of the secondary rocks, see Table II. L, p. 393; but any bed containing coal may be said to be carboniferous. Etym., Carbo, coal, and fero, to bear.

CATACLYSM. A deluge. Eiym., catacluso, to deluge.

CEPHALOPODA. A class of molluscous animals, having their organs of motion arranged round their head. Etym., cephale, head, and poda, feet.

CETACEA. An order of vertebrated mammiferous animals inhabiting the sea. The whale, dolphin, and narwal, are examples. Etym., Cete, whale.

CHALK. A white earthy limestone, the uppermost of the secondary series of strata. See Table II. F, p. 390.

CHERT. A siliceous mineral, approaching in character to flint, but less homogeneous and simple in texture.

CHLORITIC SAND. Sand coloured green by an admixture of the simple mineral chlorite. Etym., chloros, green.

COAL FORMATION. This term is generally understood to mean the same as the· Coal Measures. See Table II. L, p. 893. There are, however, 'coal formations' in all the geological periods, wherever any of the varieties of coal form a principal constituent part of a group of strata.

COLEOPTERA. An order of insects (Beetles) which have four wings, the upper pair being crustaceous and forming a shield. Etym., coleos, a shield, and pteron, a wing.

CONGENERS. Species which belong to the same genus.

CONGLOMERATE. Rounded water-worn fragments of rock, or pebbles, cemented together by another mineral substance, which may be of a siliceous, calcareous, or argillaceous nature. Etym., Con, together, glomero, to heap.

CONIFERAE. An order of plants which, like the fir and pine, bear cones or tops in which the seeds are contained. Etym., Conus, cone, and fero, to bear.

COOMB. A provincial name in different parts of England for a valley on the declivity of a hill, and which is generally without water.

CORNBRASH. A rubbly stone extensively cultivated in Wiltshire for growth of corn. It is a provincial term adopted by Smith. Brash is derived from brecan, Saxon, to break. See Table II. H, p. 391.

CORNSTONE. A provincial name for a red limestone, forming a subordinate bed in the Old Red Sandstone group.

COSMOGONY, COSMOLOGY. Words synonymous in meaning, applied to speculations respecting the first origin or mode of creation of the earth. Etym., kosmos, the world, and gonee, generation, or logos, discourse.

CRAG. A provincial name in Norfolk and Suffolk for a deposit, usually of gravel, belonging to the Older Pliocene period. See Table II. C, p. 389.

CRATER. The circular cavity at the summit of a volcano, from which the volcanic matter is ejected. Etym., Crater, a great cup or bowl.

CRETACEOUS. Belonging to chalk. Etym., Creta, chalk.

CROP OUT. A miner's or mineral surveyor's term, to express the rising up or exposure at the surface of a stratum or series of strata.

CRUST OF THE EARTH. See Earth's crust.

CRUSTACEA. Animals having a shelly coating or crust which they cast periodically. Crabs, shrimps, and lobsters are examples.

CRYPTOGAMIC. A name applied to a class of plants in which the fructification, or organs of reproduction are concealed. Etym., kryptos, concealed, and gamos, marriage.

CRYSTALS. Simple minerals are frequently found in regular forms, with facets like the drops of cut glass of chandeliers. Quartz being often met with in rocks in such forms, and beautifully transparent like ice, was called rock-crystal, crystallos, being Greek for ice. Hence the regular forms of other minerals are called crystals, whether they be clear or opake.

CRYSTALLIZED. A mineral which is found in regular forms or crystals, is said to be crystallized.

CRYSTALLINE. The internal texture which regular crystals exhibit when broken, or a confused assemblage of ill-defined crystals. Loaf- sugar and statuary-marble have a crystalline texture. Sugar-candy and calcareous spar are crystallized.

CYCADEAE. An order of plants, which are natives of warm climates, mostly tropical, although some are found at the Cape of Good Hope. They have a short stem, surmounted by a peculiar foliage, termed pinnated fronds by botanists, which spreads in a circle. The growth of these plants is by a cluster of fresh fronds shooting from the top of the stem, and pushing the former fronds outwards. These last decay down to their bases, which are broad, and. remain covering the sides of the stem. The term is derived from cycas, a name applied by the ancient Greek naturalist Theophrastus to a palm, said to grow in Ethiopia.

CVPERACEA. A tribe of plants answering to the English sedges; they are distinguished from grasses by their stems being solid and generally triangular, instead of being hollow and round. Together with gramineae they constitute what writers on botanical geography often call glumaceae.

DEBACLE. A great rush of waters, which breaking down all opposing barriers, carries forward the broken fragments of rocks, and spreads them in its course. Etym., debacler, French, to unbar, to break up as a river does at the cessation of a long-continued frost.

DELTA. When a great river before it enters the sea divides into separate streams, they often diverge and form two sides of a triangle, the sea being the base. The land included by the three lines, and which is invariably alluvial, is called a delta from its resemblance to the letter of the Greek alphabet which goes by that name . Geologists extend the boundaries of the delta, so as to include all the alluvial land outside the triangle, which has been formed by the river.

DENUDATION. The carrying away of a portion of the solid materials of the land, by which the inferior parts are laid bare. Etym., denudo, to lay bare.

DESICCATION. The act of drying up. Etym., desicco, to dry up.

DIAGONAL STRATIFICATION. For an explanation of this term, see vol. iii. p. 174.

DICOTYLEDONOUS. A grand division of the vegetable kingdom, founded on the plant having two cotyledons or seed-lobes. Etym., dis, double, and cotyledon.

DIKES. When a mass of the unstratified or igneous rocks, such as granite, trap, and lava appears as if injected into a great rent in the stratified rocks, cutting across the strata, it forms a dike; and as they are sometimes seen running along the ground, and projecting, like a wall, from the strata on both sides of them being worn away, they are called in the north of England and in Scotland dikes, the provincial name for wall. It is not easy to draw the line between dikes and veins. The former are generally of larger dimensions, and have their sides parallel for considerable distances; while veins have generally many ramifications, and these often thin away into slender threads.

DILUVIUM. Those accumulations of gravel and loose materials which, by some geologists, are said to have been produced by the action of a diluvian wave or deluge sweeping over the surface of the earth. Etym., diluvium, deluge.

DIP. When a stratum does not lie horizontally, but is inclined, the point of the compass towards which it sinks is called the dip of the stratum, and the angle it makes with the horizon is called the angle of dip or inclination.

DIPTERA. An order of insects, comprising those which have only two wings. Etym., dis double, and pteron, wing.

DOLERITE. One of the varieties of the trap-rocks, composed of augite and felspar.

DOLOMITE. A crystalline limestone, containing magnesia as a constituent part. Named after the French geologist Dolomieu.

DUNES, Low hills of blown sand that skirt the shores of Holland, Spain, and other countries. Etym., dun or dune is an Anglo-Saxon word for hill.

EARTH'S CRUST. Such superficial parts of our planet as are accessible to human observation.

ELYTRA. The wing-sheaths, or upper crustaceous membranes, which form the superior wings in the tribe of beetles, being crustaceous appendages which cover the body and protect the true membranous wing. Etym., elytron, a sheath.

EOCENE. See explanation of this word, vol. iii. p. 55.

ESCARPMENT, the abrupt face of a ridge of high land. Etym., escarper, French, to cut steep.

ESTUARIES. Inlets of the land, which are entered both by rivers and the tides of the sea. Thus we have the estuaries of the Thames, Severn, Tay, &c. Etym. AEstus, the tide.

FALUNS. A provincial name for some tertiary strata abounding in shells in Touraine, which resemble in lithological characters the 'crag' of Norfolk and Suffolk.

FAULT, in the language of miners, is the sudden interruption of the continuity of strata in the same plane, accompanied by a crack or fissure varying in width from a mere line to several feet, which is generally filled with broken stone, clay, &c., and such a displacement that the separated portions of the once continuous strata occupy different levels.

x
No. 92: The strata a, b, c, &c., must at one time have been continuous, but a fracture having taken place at the fault F, either by the upheaving of the portion A, or the sinking of the portion B, the strata were so displaced, that the bed a in B is many feet lower than the same bed a in the portion A.

FAUNA. The various kinds of animals peculiar to a country constitute its FAUNA, as the various kinds of plants constitute its FLORA. The term is derived from the FAUNI, or rural deities in Roman Mythology.

FELSPAR. A simple mineral, which constitutes the chief material of many of the unstratified or igneous rocks. The white angular portions in granite are felspar. It is originally a German miners' term. Etym., feld, field, and spath, a very old minera logical word in Germany, which seems to have been at first specially applied to a transparent kind of gypsum called selenite.

FELSPATHIC. Of or belonging to felspar.

FERRUGINOUS. Anything containing iron. Etym., ferrum, iron.

FLOETZ ROCKS. A German term applied to the secondary strata by the geologists of that country, because these rocks were supposed to occur most frequently in fiat horizontal beds. Etym., flotz, a layer or stratum; the word is applied in some parts of Germany to pavements and plastered floors.

FLORA. The various kinds of trees and plants found in any country constitute the Flora of that country in the language of botanists.

FLUVIATILE. Belonging to a river. Etym., fluvius, a river.

FORMATION. A group, whether of alluvial deposits, sedimentary strata, or igneous rocks, referred to a common origin or period.

FOSSIL. All minerals used to be called fossils, but geologists now use the word only to express the remains of animals and plants found buried in the earth. Etym,, fossilis, anything that may be dug out of the earth.

GALENA, a metallic ore, a compound of lead and sulphur. It has often the appearance of highly polished lead. Etym., galeo to shine.

GARNET. A simple mineral generally of a deep red colour, crystallized, most commonly met with in mica slate, but also in granite and other igneous rocks.

GAULT. A provincial name in the east of England for a series of beds of clay and marl, the geological position of which is between the upper and the lower greensand. See Table II. F, p. 390.

GEOLOGY, GEOGNOSY. Both mean the same thing, but with an unnecessary degree of refinement in terms, it has been proposed to call our description of the structure of the earth geognosy. (Etym., gea, earth, and ginosco, to know,) and our theoretical speculations as to its formation geology. (Etym., and logos, a discourse.

GLACIER. The vast accumulations of ice and hardened snow in the Alps and other lofty mountains. Etym. glace, French for ice.

GLACIS. A term borrowed from the language of fortification, where it means an easy insensible slope or declivity, less steep than a talus, which see.

GNEISS. A stratified primary rock, composed of the same materials as granite, but having usually a larger proportion of mica, and a laminated texture. The word is a German miner's term.

GRAMINEAE, the order of plants to which grasses belong. Etym., gramen, grass.

GRANITE. An unstratified or igneous rock, generally found inferior to or associated with the oldest of the stratified rocks, and sometimes penetrating them in the form of dikes and veins. It is composed of three simple minerals, felspar, quartz, and mica, and derives its name from having a coarse granular structure; granum, Latin for grain. Westminster, Waterloo, and London bridges, and the paving-stones in the carriage-way of the London streets are good examples of the most common varieties of granite.

GRAUWACKE, a German name, generally adopted by geologists for the lowest members of the secondary strata, consisting of sandstone and slate, and which form the chief part of what are termed by some geologists the transition rocks. The rock is very often of a grey colour, hence the name, grau being German for grey, and wacke being a provincial miner's term.

GREENSAND. Beds of sand, sandstone, limestone, belonging to the Cretaceous Period. See Table II. F, p. 390. The name is given to these beds, because they often, but not always, contain an abundance of green earth or chlorite scattered through the substance of the sandstone, limestone, &c. See vol. iii. p. 324.

GREENSTONE, a variety of trap, composed of hornblende and felspar.

GRIT, a provincial name for a coarse-grained sandstone.

GYPSUM, a mineral composed of lime and sulphuric acid, hence called also sulphate of lime. Plaster and stucco are obtained by exposing gypsum to a strong heat. It is found so abundantly near Paris, that Paris plaster is a common term in this country for the white powder of which casts are made. The term is used by Pliny for a stone used for the same purposes by the ancients. The derivation of it is unknown.

GYPSEOUS, of, or belonging to, gypsum.

GYROGONITES. Bodies found in fresh-water deposits, originally supposed to be microscopic shells, but subsequently discovered to be the seed-vessel of fresh-water plants of the genus chara. See vol. ii. p. 273, and 2d Edit. p. 280. Etym. gyros, curved, and gonos, seed, on account of their external structure.

HEMIPTERA, an order of insects, so called from a peculiarity in their wings, the superior being coriaceous at the base, and membranous at the apex, hemisu, half, and pteron, wing.

HORNBLENDE, a simple mineral of a dark green or black colour, which enters largely into the composition of several varieties of the trap rocks.

HYDROPHYTES. Plants which grow in water. Etym., hydor, water, and phyton, plant.

HYPOGENE ROCKS. For an explanation of this term, see vol. iii. p. 374.

ICEBERG. The great masses of ice, often the size of hills, which float in the polar and northern seas. Etym., ice, and berg, German for hill.

ICHTHYOSAURUS, a gigantic fossil marine reptile, intermediate between a crocodile and a fish. Etym., ichthus, a fish, and saura, a lizard.

INDUCTION, a consequence, conclusion or inference, drawn from propositions or principles first laid down, or from the observation and examination of phenomena.

INFUSORY ANIMALCULES. Minute living creatures generated in many infusions; and the term infusoria has been given to all such animalcules whether found in infusions or in stagnant water, vinegar, &c.

INSPISSATED, Thickened. Etym., spissus, thick.

INVERTEBRATED ANIMALS. Animals which are not furnished with a back-bone. For a further explanation, see "Vertebrated Animals."

ISOTHERMAL. Such zones or divisions of the land, ocean, or atmosphere, which have an equal degree of mean annual warmth, are said to be isothermal, from isos, equal, and therme, heat.

JURA LIMESTONE. The limestones belonging to the oolite group, see Table II. H, p. 391, constitute the chief part of the mountains of the Jura, between France and Switzerland, and hence the geologists of the Continent have given the name to the group.

KIMMERIDGE CLAY, a thick bed of clay, constituting a member of the Oolite Group. See Table II. H, p. 391. so called because it is found well developed at Kimmeridge in the isle of Purbeck, Dorsetshire.

LACUSTRINE, belonging to a lake. Etym., Lacus, a lake.

LAMINAE. Latin for plates; used in geology, for the smaller layers of which a stratum is frequently composed.

LAMANTINE. A living species of the herbivorous cetacea or whale tribe, which inhabits the mouths of rivers on the coasts of Africa and South America; the sea-cow.

LAMELLIFEROUS. A stone composed of thin plates or leaves like paper. Etym., lamella, the diminutive of lamina, plate, and fero, to bear.

LANDSLIP. A portion of land that has slid down in consequence of disturbance by an earthquake, or from being undermined, by water washing away the lower beds which supported it.

LAPIDIFICATION -- Lapidifying process. Conversion into stone. Etym., lapis, stone, and fio, to make.

LAPILLI. Small volcanic cinders. Lapillus, a little stone.

LAVA. The stone which flows in a melted state from a volcano.

LEUCITE. A simple mineral found in volcanic rocks, crystallized, and of a white colour. Etym., leucos, white.

LIAS. A provincial name, adopted in scientific language, for a particular kind of limestone, which being characterized, together with its associated beds, by peculiar fossils, is formed in this work into a particular group of the secondary strata. See Table II. I, p. 392.

LIGNIPERDOUS. A term applied to insects which destroy wood. Etym. lignum, wood, and perdo, to destroy.

LIGNITE. Wood converted into a kind of coal. Etym., lignum, wood.

LITHODOMI. Molluscous animals which bore into solid rocks, and lodge themselves in the holes they have formed. Etym., lithos, stone, and domus, house.

LITHOLOGICAL. A term expressing the stony structure or character of a mineral mass. We speak of the lithological character of a stratum as distinguished from its zoological character. Etym., lithos, stone, and logos, discourse.

LITHOPHAGI. Molluscous animals which bore into solid stones. Etym., lilhos, stone, and phagein, to eat.

LITTORAL. Belonging to the sea-shore. Etym., littus, the shore.

LOAM. A mixture of sand and clay.

LYCOPODIACEAE. Plants of an inferior degree of organization to Coniferae, some of which they very much resemble in foliage, but all recent species are infinitely smaller. Many of the fossil species are as gigantic as recent coniferae. Their mode of reproduction is analogous to that of ferns. In English they are called club-mosses, generally found in mountainous heaths in the north of England.

MADREPORE. A genus of corals, but generally applied to all the corals distinguished by superficial star-shaped cavities. There are several fossil species.

MAGNESIAN LIMESTONE. An extensive series of beds lying in geological position, immediately above the coal-measures, so called because the limestone, the principal member of the series. contains much of the earth magnesia as a constituent part. See Table II. K, p. 392.

MAMMILLARY. A surface which is studded over with rounded projections. Etym., mammilla, a little breast or pap.

MAMMIFEROUS. Animals which give suck to their young. Etym., mamma, a breast, and fero, to bear.

MAMMOTH. An extinct species of the elephant (E. primigenius), of which the fossil bones are frequently met with in various countries. The name is of Tartar origin, and is used in Siberia for animals that burrow underground.

MARL. A mixture of clay and lime; usually soft, but sometimes hard, in which case it is called indurated marl.

MARSUPIAL ANIMALS. A tribe of quadrupeds having a sack or pouch under the belly, in which they carry their young. The kangaroo is a well-known example. Etym., marsupium, a purse.

MASTODON. A genus of fossil extinct quadrupeds allied to the elephant. So called from the form of the hind teeth or grinders, which have their surface covered with conical mammillary crests. Etym., mastos, mammilla or little pap, and odon, tooth.

MATRIX. If a simple mineral or shen, in place of being detached, be still fixed in a portion of rock, it is said to be in its matrix. Matrix, womb.

MECHANICAL ORIGIN, Rocks of. When rocks are composed of sand, pebbles, or fragments, to distinguish them from those of an uniform crystalline texture, which are of chemical origin.

MEDUSAE. A genus of marine radiated animals, without shells; so called because their organs of motion spread out like the snaky hair of the fabulous Medusa.

MEGALOSAURUS. A fossil gigantic amphibious animal of the saurian or lizard and crocodile tribe. Etym., megale, great, and saura, lizard.

MEGATHERIUM. A fossil extinct quadruped, resembling a gigantic sloth. Etym., mega, great, and therion, wild-beast.

MELASTOMA. A genus of MELASTOMACEA, an order of plants of the evergreen tree, and shrubby exotic kinds. Etym., melas, black, and stoma, mouth; because the fruit of one of the species stains the lips.

MESOTYPE. A simple mineral, white, and needle-shaped, one of the Zeolite family, frequently met with in the trap rocks.

METAMORPHIC ROCKS. For an explanation of this term, see vol. iii. p. 374.

MICA. A simple mineral, having a shining silvery surface, and capable of being split into very thin elastic leaves or scales. It is often called talc in common life, but mineralogists apply the term talc to a different mineral. The brilliant scales in granite are mica. Etym., mica, to shine.

MICA-SLATE, MICA-SCHIST, MICACEOUS SCHISTUS. One of the lowest of the stratified rocks, belonging to the primary class, which is characterized by being composed of a large proportion of mica, united with quartz.

MIOCENE. See an explanation of this term, vol. iii. p. 54.

MOLASSE. A provincial name for a soft, green sandstone, associated with marl and conglomerates, belonging to the Miocene tertiary period, extensively developed in the lower country of Switzerland. See vol. iii. p. 212.

MOLLUSCAE, Molluscous Animals. Animals, such as shell-fish, which, being devoid of bones, have soft bodies. Etym., mollis, soft.

MONITOR. An animal of the saurian or lizard tribe, species of which are found in both the fossil and recent state.

MONOCOTYLEDONOUS. A grand division of the vegetable kingdom, founded on the plant having only one cotyledon, or seed-lobe. Etym., monos, single.

MOSCHUS. The quadruped resembling the chamois or mountain-goat, from which the perfume musk is obtained.

MOUNTAIN LIMESTONE. A series of limestone strata, of which the geological position is immediately below the coal measures, and with which they also sometimes alternate. See Table II. L, p. 393.

MOYA. A term applied in South America to mud poured out from volcanos during eruptions.

MURIATE OF SODA. The scientific name for common culinary salt, because it is composed of muriatic acid and the alkali soda.

MUSACEAE. A family of tropical monocotyledonous plants, including the banana and plantains.

MUSCHELKALK. A limestone which, in geological position, belongs to the red sandstone group. This formation has not yet been found in England, and the German name is adopted by English geologists. The word means shell-limestone: muschel, shell, and kalkstein, limestone. See Table II. K, p. 392.

NAPHTHA. A very thin, volatile, inflammable, and fluid mineral substance, of which there are springs in many countries, particularly in volcanic districts.

NENUPHAR. A yellow water-lily.

NEW RED SANDSTONE. A series of sandy, argillaceous, and often calcareous strata, the predominant colour of which is brick-red, but containing portions which are of a greenish grey. These occur often in spots and stripes, so that the series has sometimes been called the variegated sandstone. The European formation so called lies in a geological position immediately above the coal-measures. See Table II. K, p. 392.

NODULE. A rounded irregular-shaped lump or mass. Etym., diminutive of nodus, knot.

NORMAL GROUPS. Groups of certain rocks taken as a rule or standard. Etym. norma, rule or pattern.

NUCLEUS. A solid central piece, around which other matter is collected. The word is Latin for kernel.

NUMMULITES. An extinct genus of the Order of Molluscous animals, called Cephalopoda, of a thin lenticular shape, internally divided into small chambers. Etym., nummus, Latin for money, and lithos, stone, from its resemblance to a coin.

OBSIDIAN. A volcanic product, or species of lava, very like common green bottle-glass, which is almost black in large masses, but semi-transparent in thin fragments. Pumice-stone is obsidian in a frothy state; produced most probably by water that was contained in or had access to the melted stone, and converted into steam. There are very often portions in a mass of solid obsidian, which are partially converted into pumice.

OGYGIAN DELUGE. A general inundation of fabulous history, which is supposed to have taken place in the reign of Ogyges in Attica, whose death is fixed in Blair's Chronological Tables in the year 1764 before Christ.

OLD RED SANDSTONE. A stratified rock belonging to the Carboniferous group. See Table L, p. 393.

OLIVINE. An olive-coloured, semi-transparent, simple mineral, very often occurring in the forms of grains and of crystals in basalt and lava.

OOLITE, Oolitic. A limestone, forming a characteristic feature of a group of the secondary strata. See Table II. H, p. 391. It is so named, because it is composed of rounded particles, like the roe or eggs of a fish. Etym. oon, egg, and lithos, stone.

OPALIZED WOOD. Wood petrified by siliceous earth, and acquiring a structure similar to the simple mineral called opal.

OPHIDIOUS REPTILES. Vertebrated animals, such as snakes and serpents. Etym., ophis, a serpent.

ORGANIC REMAINS. The remains of animals and plants; organized bodies, found in a fossil state.

ORTHOCERATA. An extinct genus of the order of Molluscous Animals, called Cephalopoda, that inhabited a long chambered, conical shell, like a straight horn. Etym., orthos, straight, and ceras, horn.

OSSEOUS BRECCIA. The cemented mass of fragments of bones of extinct animals found in caverns and fissures. Osseus is a Latin adjective, signifying bony.

OUTLIERS. When a portion of a stratum occurs at some distance, detached from the general mass of the formation to which it belongs, some practical mineral surveyors call it an outlier, and the term is adopted in geological language.

OVATE. The shape of an egg. Etym., ovum, egg.

OVIPOSITING. The laying of eggs.

OXYGEN. One of the constituent parts of the air of the atmosphere; that part which supports life. For a further explanation of the word, consult elementary works on chemistry.

OXIDE. The combination of a metal with oxygen; rust is oxide of iron.

PACHYDERMATA. An order of quadrupeds, including the elephant, rhinoceros, horse, pig, &c., distinguished by having thick skins. Etym. pachus, thick, and derma, skin or hide.

PACHYDERMATOUS. Belonging to pachydermata.

PALAEOTHERIUM, PALEOTHERE. A fossil extinct quadruped, belonging to the order pachydermata, resembling a pig or tapir, but of great size. Etym. palaios, ancient, and therion, wild beast.

PELAGIAN, PELAGIC. Belonging to the deep sea. Etym. pelagus, sea.

PEPERINO. An Italian name for a particular kind of volcanic rock, formed, like tuff, by the cementing together of volcanic sand, cinders, or scoriae, &c.

PETROLEUM. A liquid mineral pitch, so called because it is seen to ooze like oil out of the rock. Etym. petra, rock, and oleum, oil.

PHANEROGAMIC PLANTS, A name given by Linnaeus to those plants in which the reproductive organs are apparent. Etym. phaneros, evident, and gamos, marriage.

PHYSICS. The department of science, which treats of the properties of natural bodies, laws of motion, &c., sometimes called Natural philosophy and mechanical philosophy. Etym. physis, nature.

PHYTOLOGY, PHYTOLOGICAL. The department of science which relates to plants-synonymous with botany and botanical. Etym. phyton, plant, and logos, discourse.

PHYTOPHAGOUS. Plant eating. Etym. phyton, plant, and phagein, to eat.

PISLIAR, a misprint for PISTIA, in vol. ii. p. 98, 1st ed., p. 102, 2d ed. The plant mentioned by Malte-Brun is probably the Pistia stratiotes, a floating plant, related to English duck-weed, but very much larger.

PISOLITE. A stone possessing a structure like an agglutination of pease. Etym. pison, pea, and lithos, stone.

PIT COAL. Ordinary coal; called so because it is obtained by sinking pits in the ground.

PITCH STONE. A rock of an uniform texture, belonging to the unstratified and volcanic classes, which has an unctuous appearance, like indurated pitch.

PLASTIC CLAY. One of the beds of the Eocene tertiary period (see Table II. E, p. 390.) It is so called because it is used for making pottery. Etym. plasso, to form or fashion.

PLESIOSAURUS. A fossil extinct amphibious animal, resembling the saurian, or lizard and crocodile tribe. Etym. plesion, near to, and saura, a lizard.

PLIOCENE. See explanation of this term, vol. iii. p. 53.

PLUTONIC ROCKS. For an explanation of this term, see vol. iii. p. 353.

POLYPARIA. CORALS. A numerous class of invertebrated animals, belonging to the great division called Radiata.

PORPHYRY. An unstratified or igneous rock. The term is as old as Pliny, and was applied to a red rock with small angular white bodies diffused through it, which are crystallized felspar, brought from Egypt. The term is hence applied to every species of unstratified rock, in which detached crystals of felspar are diffused through a base of other mineral composition. Etym. porphyra, purple.

PORTLAND LIMESTONE, PORTLAND BEDS. A series of limestone strata, belonging to the upper part of the Oolite group (see Table II. H, p. 391.), found chiefly in England, in the Island of Portland on the coast of Dorsetshire. The great supply of the building stone used in London is from these quarries.

POZZUOLANA. Volcanic ashes, largely used as mortar for buildings, similar in nature to what is called in this country Roman cement. It gets its name from Pozzuoli. a town in the bay of Naples, from which it is shipped in large quantities to all parts of the Mediterranean.

PRODUCTAE. An extinct genus of fossil bivalve shells, occurring only in the older of the secondary rocks. It is closely allied to the living genus Terebratula.

PUBESCENCE. The soft hairy down on insects. Etym., pubesco, the first growth of the beard.

PUMICE. -- A light spongy lava, of a white colour, produced by gases, or watery vapour getting access to the particular kind of glassy lava called obsidian, when in a state of fusion -- it may be called the froth of melted volcanic glass. The word comes from the Latin name of the stone, pumex.

PURBECK LIMESTONE, PURBECK BEDS. Limestone strata belonging to the Wealden group. See Table II. G, p. 390.

PYRITES (Iron). A compound of sulphur and iron, found usually in yellow shining crystals like brass, and in almost every rock stratified and unstratified. The shining metallic bodies, so often seen in common roofing slate, are a familiar example of the mineral. The word is Greek, and comes from pyr. fire, because, under particular circumstances, the stone produces spontaneous heat and even inflammation.

QUADRUMANA. The order of mammiferous animals to which apes belong. Etym., quadrus, a derivation of the Latin word for the number four, and manus, hand, -- the four feet of those animals being in some degree usable as hands.

QUA-QUA-VERSAL DIP. The dip of beds to all points of the compass around a centre, as in the case of beds of lava round the crater of a volcano. Etym., qua-qua versum, on every side.

QUARTZ. A German provincial term, universally adopted in scientific language, for a simple mineral composed of pure silex, or earth of flints; rock-crystal is an example.

RED MARL. A term often applied to the New Red Sandstone, which is the principal member of the Red Sandstone group. See Table II. K, p. 392.

RETICULATE. A structure of cross lines, like a net, is said to be reticulated, from rete, a net.

ROCK SALT.. Common culinary salt, or muriate of soda, found in vast solid masses or beds, in different formations, extensively in the New Red Sandstone formation, as in Cheshire, and it is then called rock-salt.

RUMINANTIA. Animals which ruminate or chew the cud. Etym., the Latin verb rumina, meaning the same thing.

SACCHAROID, SACCHARINE. When a stone has a texture resembling that of loaf-sugar. Etym., sacchar, sugar, and eidos, form.

SALIENT ANGLE. In a zig-zag line, a a are the salient angles, b b the re-entering angles. Etym., salire, to leap or bound forward.

x
No. 93.

SALT SPRINGS. Springs of water containing a large quantity of common salt. They are very abundant in Cheshire and Worcestershire, and culinary salt is obtained from them by mere evaporation.

SANDSTONE. Any stone which is composed of an agglutination of grains of sand, which may be either calcareous or siliceous.

SAURIAN. Any animal belonging to the lizard tribe. Etym., saura, a lizard.

SCHIST. Synonymous with slate. Etym., part of the Latin verb scindo, to split, from the facility with which slaty rocks may be split into thin plates.

SCHISTOSE ROCKS. Synonymous with slaty rocks.

SCORIAE. Volcanic cinders. The word is Latin for cinders.

SEAMS. Thin layers which separate two strata of greater magnitude.

SECONDARY STRATA. An extensive series of the stratified rocks which compose the crust of the globe, with certain characters in common, which distinguish them from another series below them, called primary, and from a third series above them called tertiary. See vol. iii. p. 324, and Table II. p. 390.

SECULAR REFRIGERATION. The periodical cooling and consolidation of the globe, from a supposed original state of fluidity from heat. Saeculum, age or period.

SEDIMENTARY ROCKS, are those which have been formed by their materials having been thrown down from a state of suspension or solution in water.

SELENITE. Crystallized gypsum, or sulphate of lime -- a simple mineral.

SEPTARIA. Flattened balls of stone, generally a kind of iron-stone, which, on being split, are seen to be separated in their interior into irregular masses. Etym., septa, inclosures.

SERPENTINE. A rock usually containing much magnesian earth, for the most part unstratified, but sometimes appearing to be an altered or metamorphic stratified rock. Its name is derived from frequently presenting contrasts of colour, like the skin of some serpents.

SHALE. A provincial term, adopted in geological science, to express an indurated slaty clay. Etym., German schalen, to peal, to split.

SHELL MARL. A deposit of clay, peat, and other substances mixed with shells, which collects at the bottom of lakes.

SHINGLE. The loose and completely water-worn gravel on the seashore.

SILEX. The name of one of the pure earths, being the Latin word for flint, which is wholly composed of that earth. French geologists have applied it as a generic name for all minerals composed entirely of that earth, of which there are many of different external forms.

SILICA. One of the pure earths. Etym., silex, flint, because found in that mineral.

SILICATE. A chemical compound of silica and another substance, such as silicate of iron. Consult elementary works on chemistry.

SILICEOUS. Of or belonging to the earth of flint. Etym., silex, which see. A siliceous rock is one mainly composed of silex.

SILICIFIED. Any substance that is petrified or mineralized by siliceous earth.

SILT. The more comminuted sand, clay, and earth, which is transported by running water. It is often accumulated by currents in banks. Thus we speak of the mouth of a river being silted up when its entrance into the sea is impeded by such accumulation of loose materials.

SIMPLE MINERAL. Individual mineral substances, as distinguished from rocks, which last are usually an aggregation of simple minerals. They are not simple in regard to their nature, for when subjected to chemical analysis, they are found to consist of a variety of different substances. Pyrites is a simple mineral in the sense we use the term, but it is a chemical compound of sulphur and iron.

SOLFATARA. A volcanic vent from which sulphur, sulphureous, watery, and acid vapours and gases are emitted.

SPORULES. The reproductory corpuscula (minute bodies) of cryptogamic plains. Etym., , spora, a seed.

STALACTITE. When water holding lime in solution deposits it as it drops from the roof of a cavern, long rods of stone hang down like icicles, and these are called stalactites. Etym., stalazo, to drop.

STALAGMITE. When water holding lime in solution drops on the floor of a cavern, the water evaporating leaves a crust composed of layers of limestone; such a crust is called stalagmite, from stalagma, a drop, hi opposition to stalactite, which see.

STILBITE. A white crystallized simple mineral, one of the Zeolite family, frequently included in the mass of the trap rocks.

STRATIFIED. Rocks arranged in the form of strata, which see.

STRATIFICATION. An arrangement of rocks in strata, which see.

STRATUM, STRATA. When several rocks lie like the leaves of a book, one upon another, each individual forms a stratum; -- strata is the plural of the word. Etym., stratum, part of a Latin verb signifying to strew or layout.

STRIKE. The direction or line of bearing of strata, which is always at right angles to their prevailing dip. For a fuller explanation, see vol. iii. p. 346.

SUBAPENNINES. Low hills which skirt or lie at the foot of the great chain of the Apennines in Italy. The term Subapennine is applied geologically to a series of strata of the Older Pliocene period.

SYENITE. A kind of granite, so called because it was brought from Syene in Egypt. For geological acceptation of the term, see vol. iii. p. 358.

SYNCLINAL AXIS. See explanation of this term, vol. iii. p. 293.

TALUS. When fragments are broken off by the action of the weather from the face of a steep rock, as they accumulate at its foot, they form a sloping heap, called a talus. The term is borrowed from the language of fortification, where talus means the outside of a wall of which the thickness is diminished by degrees, as it rises in height, to make it the firmer.

TARSI. The feet in insects, which are articulated, and formed of five or a less number of joints.

TERTIARY STRATA. A series of sedimentary rocks, with characters which distinguish them from two other great series of strata, -- the secondary and primary, which lie beneath them. See Tables, p. 61, &c.

TESTACEA. Molluscous animals, having a shelly covering. Etym., testa, a shell, such as snails, whelks, oysters, &c.

THIN OUT. When a stratum, in the course of its prolongation in any direction, becomes gradually less in thickness, the two surfaces approach nearer and nearer; and when at last they meet, the stratum is said to thin out, or disappear.

TRACHYTE. A variety of lava essentially composed of glassy felspar, and frequently having detached crystals of felspar in the base or body of the stone, giving it the structure of porphyry. It sometimes contains hornblende and augite; and when these last predominate, the trachyte passes into the varieties of trap called greenstone, basalt, dolorite, &c. The term is derived from trachus, rough, because the rock has a peculiar rough feel.

TRAP and TRAPPEAN ROCKS. Volcanic rocks composed of felspar, augite, and hornblende. The various proportions and state of aggregation of these simple minerals, and differences in external forms, give rise to varieties, which have received distinct appellations, such as basalt, amygdaloid, dolorite, greenstone, and others. The term is derived from trappa, a Swedish word for stair, because in Sweden the rocks of this class often occur in large tabular masses, rising one above another, like the steps of a staircase. For further explanation, see vol. iii. p. 359.

TRAVERTIN. A limestone, usually hard and semi-crystalline, deposited from the water of springs holding lime in solution. The word is Italian, and a corruption of the term Tiburtinus, the stone being formed in great quantity by the river Anio, at Tibur, near Rome, and hence it was called by the ancients Lapis Tiburtinus.

TROPHI, of Insects. Organs which form the mouth, consisting of an upper and under lip, and comprising the parts called mandibles, maxillae, and palpi.

TUFF, or TUFO. An Italian name for a variety of volcanic rock, of an earthy texture, seldom very compact, and composed of an agglutination of fragments of scoriae and loose matter ejected from a volcano.

TUFACEOUS. A rock with the texture of tuff or tufo, which see.

TURBINATED. Shells which have a spiral or screw-form structure. Etym., turbinatus, made like a top.

VEINS, Mineral. Cracks in rocks filled up by substances different from the rock, which may either be earthy or metallic. Veins are sometimes many yards wide; and they ramify or branch off into innumerable smaller parts, often as slender as threads, like the veins in an animal, and hence their name.

VERTEBRATED ANIMALS. A great division of the animal kingdom, including all those which are furnished with a back-bone, as the mammalia, birds, reptiles, and fishes. The separate joints of the back-bone are called vertebre, from the Latin verb verta, to turn.

VESICLE. A small circular inclosed space, like a little bladder. Etym., diminutive of vesica, Latin for a bladder.

VOLCANIC BOMBS. Volcanos throw out sometimes detached masses of melted lava, which, as they fall, assume rounded forms (like bomb-shells), and are often elongated into a pear shape.

VOLCANIC FOCI. The subterranean centres of action in volcanos, where the heat is supposed to be in the highest degree of energy.

ZEOLITE. A family of simple minerals, including stilbite, mesotype, analcime, and some others, usually found in the trap or volcanic rocks. Some of the most common varieties swell or boil up when exposed to the blow-pipe, and hence the name of zeo, to froth, and lithos, stone.

ZOOPHYTES. Corals, sponges, and other aquatic animals allied to them, so called because, while they are the habitation of animals, they are fixed to the ground, and have the forms of plants. Etym., zoon, animal, and phyton, plant.
admin
Site Admin
 
Posts: 28480
Joined: Thu Aug 01, 2013 5:21 am

Re: Principles of Geology, by Charles Lyell

Postby admin » Fri Jul 17, 2015 4:12 am

PART 1 OF 2

INDEX

VOL. III.


ABERDEENSHIRE, passage from trap into
granite in, 361
Abesse, near Dax, section of inland cliff at,
-- see wood-cut No. 53, 210
Acquapendente, alternations of volcanic
tuffs with the Subapennine marls at,
159
Adanson on the age of the baobab tree, 99
Addington hills, 279
Aderno, opposite dip of the strata in two
sections near, 78
Adour, section of tertiary strata in the valley
of the -- see diag, No. 51, 207
Adur, view of the transverse valley of the
river -- see wood-cut No. 73, 299
Agassiz, M., on fossil fish of the brown
coal formation, 200
-- on the fossil fish of the Paris basin,
253
-- on the distinctness of the secondary
and tertiary fossil fish, 327
Age of volcanos, mode of computing the, 97
Ages, relative, of rocks how determined, 35
Aidat, Lake, how formed, 269
Aix, in Provence, tertiary strata of, 276
-- fossil insects abundant in the calcareous
marl of, 277
Albenga, height of the tertiary strata above
the sea at, 165, 166
-- resemblance of the strata at, to
the Subapennines, 167
Allan, Mr. T., his discovery of the bones
of mammalia in the fresh-water strata of
the Isle of Wight, 281
Allier, river, section of volcanic tuff and
fresh-water limestone on the banks of
the, 258
Alluvium, passage of marine crag strata
into, 181
-- ancient, of the valley of the Rhine,
200
-- of the Weald valley, 295
Alluviums formed in all ages, 145
-- of the newer Pliocene period, 139,
145, 151
-- distinction between regular subaqueous
strata and, 145
-- marine, 145
-- British, how formed, 147
-- European, in great part tertiary, 150
Alluviums, underlying lavas of Catalonia,
188, 189, 190, 192
-- of the Miocene era, localities of,
217
-- trachytic breccias alternating with,
in Auvergne -- see wood-cut No. 54, 217
-- of Auvergne, extinct quadrupeds in,
218
-- of different ages covered by lava in
Auvergne -- see wood-cut No. 61, 266
-- of the Eocene period, 317
Alps, shells drifted into the Mediterranean
from the, 48
-- erratic blocks of the, 148
-- Maritime, tertiary strata at the base
of the, 164
-- secondary strata penetrated by granite
in the, 358
-- strata of oolite altered in the, 371
Altered strata in contact with granite, 370,
371
-- strata, enumeration of the probable
conversions of sedimentary strata
into well-known metamorphic rocks, 373
Alternations of strata with and without
organic remains, how caused, 254
Alum Bay, alternation of the London and
plastic clay in, 278
Amer, geological structure of the country
near, 185
Anapo, valley of the, 111
Andernach, gorge of, 152
--- loess and volcanic ejections
alternating at, 153
Andes, sudden rise of the, said to have
caused the historical deluge, 148
Angers, fossil shells found at -- see tables
Appendix I.
Anglesea, changes caused by a volcanic
dike in, 368
Animals, their fossilization partial, 31
-- remains of, in the successive tertiary
periods, 59
Anoplotherium found in the fresh-water
formation of the Isle of Wight, 281, 317
Anthracite, whence derived, 373
Anticlinal axis of the Weald valley -- see
wood-cuts Nos. 63 and 64, 288
Anticlinal and synclinal lines described -- see
wood-cut No. 68, 293
Anticlinal lines, how far those formed at
the same time are parallel, 349
Antilles, recent shells imbedded in limestone
in the, 133
Antrim, chalk in, converted into marble by
trap-dike, 369
--- altered coal and lias in, 369
Apennines, tertiary strata at the foot of the,
155
Apollinaris does not mention the volcanos
in his description of Auvergne, 269
Areas of sedimentary deposition, shifting
of the, 26
Argillaceous strata, change caused by a
dike of lava in, 70
Arno, river, yellow sand like the Subapennines
deposited by the, 161
Arun, transverse valley of the, 298, 299
Asia, western, great cavity in, 29, 270
Astroni, crater of, 187
Atlantis of Plato, 330
Atrio del Cavallo, dikes in the, 124
Aurillac, fresh-water formation of, 236
-- silex abundant in the fresh-water
strata of, 237
-- resemblance of the fresh-water
lime-stone and flints to the chalk, 237
-- proofs of the gradual deposition of
the fresh-water marls of, 239
Australian breccias, bones of marsupial
animals in, 143
Auvergne, appearance of some of the lavas
of, 94
-- position of the Miocene alluviums of
-- see wood-cut No. 54, 217
-- extinct quadrupeds in the alluviums
of, 218
-- age of the volcanic rocks of, 224
-- lacustrine deposits of, 226
-- map of the lacustrine basins and
volcanic rocks of -- see wood-cut No.
56, 226
-- tertiary red marl and sandstone of,
like new red sandstone, 229, 333
-- indusial limestone of, 232
-- dip of the tertiary strata of, 233, 235
-- arrangement and origin of the freshwater
formation of, 233
-- analogy of the tertiary deposits of,
to those of the Paris basin, 241
-- geographical connexion of the Paris
basin and, 241
-- probably once connected with the
Paris basin by a chain of lakes, 241
--volcanic rocks of, 257
-- igneous rocks associated with the
lacustrine strata of, 258
-- volcanic breccias of, how formed, 259
-- minor volcanos of, 260, 263
-- long succession of eruptions in, 260
-- ravines excavated through lava in,
264
Auvergne, lavas resting on alluviums of different
ages in -- see wood-cut No. 61, 266
-- age of the volcanos of, 268, 269
Aventine, Mount, a deposit of calcareous
tufa on, 138

Bagneux, alternation of plastic clay and
calcaire grossier at, 244
Bagshot sand, its composition, &c., 280
Banos del Pujio, elevated sea-cliff near,
131
Baobab tree, its size, probable age, &c.,
99, 272
Baraque, la Petite, section of vertical
marls in a ravine near-see wood-cut
No. 57, 231
Barcelona, height of the marine tertiary
strata of, 193
Barcombe, section from the north escarpment
of the South Downs to-see woodcut
No. 71, 296
Barzone, gypsum found in the Subapennine
marls near, 159
Basalt, theory of the aqueous origin of, 4
Basalts of the Bay of Trezza, Paterno, &c.,
their relative age, 82
Basterot, M. de, on the fossil shells of
Bordeaux and Dax, 20, 206
Battoch, Mount, granite veins of, 357
Bay of Trezza, sub-Etnean formations exposed
in the, 78
-- proofs of ancient submarine eruptions
in the, 78
Bayonne, age of the tertiary strata near,
343
-- age of the newest secondary strata
near, 343
Bawdesey, inclination of the crag strata
near, 174
Beauchamp, remains of a palaeotherium and
fresh-water shells in calcaire grossier
at, 252
Beachy Head, termination of the chalk
escarpment at, 291
-- thickness of the upper green-sand
at, 292
Beginning of things, supposed proofs of,
383
Belbet, section of white limestone in the
quarry of, 237
Belgium, tertiary formations of, 276
-- fossil shells from-see table, Appendix
I.
Beliemi, Mount, caves in, 143
Beudant, M., on the volcanic rocks of
Hungary, 222
Bingen, gorge of, 152
Binstead, mammiferous remains found in
the quarries of, 281, 317
Blaye, limestone of, 208
-- its position-see wood-cut No. 52,
209
Blue marl with shells of the Val di Noto,
67
Boblaye, M., on the successive elevations
of the Morea, 113, 132 .
-- on the formation of osseous breccias
in the Morea, 144
-- on the tertiary strata of the Morea,
170
Bolos, Don Francisco, on the volcanos of
Olot, in Catalonia, 187, 191, 193
-- on the destruction of Olot by earth.
quake, in 1421, 191
Bonelli, Signor, on the fossil shells of
Savona, 166
-- on the fossil shells of the Superga,
211
Bonn, blocks of quartz containing casts of
fresh-water shells found near, 199
-- remains of frogs from the brown coal
formation in the museum at, 200
Bordeaux, tertiary strata of, 20, 206
-- Eocene strata in the basin of, 208
-- fossil shells of -- see table, Appendix
I.
Bormida, tertiary strata of the valley of
the, 211
Bosque de Tosca, a mound of lava near
Olot, 186
Botley Hill, height of, 288
Boue, M., on the loess of the valley of the
Rhine, 151
-- on the value of zoological characters
in determining the chronological
relations of strata, 208
-- term molasse vaguely employed by,
212
-- on the tertiary formations of Hungary
and Transylvania, 213
-- on the fossil shells of Hungary,
223
-- on the volcanic rocks of Transylvania,
223
-- his objections to the theory of M.
Elie de Beaumont, 346, 347
Bouillet, M., on the extinct quadrupeds of
Mont Perrier, 218
-- on alluviums of different ages in
Auvergne, 267
Boulade, position of the alluviums of the
-- see wood-cut No. 54, 217
Boulon and Ceret, dip of the tertiary
strata between, 170
Bourbon, Isle of, a volcanic eruption every
two years in the, 363
Bowdich, Mr., fossil shells of recent species
brought from Madeira by, 134
Braganza river, brown clay deposited by
the, 161
Breaks in the series of superimposed for.
mations, causes of, 26, 33
Breccias in the Val del Bove, 93
-- osseous, in Sicilian caves, 139
Breccias, in Australian caves, 143
-- now in progress in the Morea,
144
-- trachytic, alternations of alluvium
and-see wood-cut No. 54, 217
-- volcanic, of Auvergne, 259
Brighton, deposit containing recent shells
in the cliffs near, 182
British alluviums, how formed, 147
-- their age, 147, 272
Brocchi on the tertiary strata of the
Subapennines, 18, 155
-- on the number of shells common to
Italy and the Paris basin, 156
-- on the age of the Italian tertiary
strata, 156
-- on the organic remains of the sub-Apennine
strata, 163
Bromley, pebble with oysters attached to
it found in the plastic clay at, 278
Brongniart, M. Alex., on the formations of
the Paris basin, 16
-- on the conglomerate of the hill of
the Superga, 211
-- tabular view of his arrangement of
the strata of the Paris basin-see woodcut
No. 58, 243, 247
Bronn, M., on the loess of the Rhine, 151,
153, 154
Brown coal formation near the valley of
the Rhine, 199
-- organic remains of the, 200
Bruel, quarry of, 237
Buckland, Dr., on the Val del Bove, 83
-- on the grooved summits of the Corstorphine
Hills, 147
-- on the effects of the Deluge, 271
-- on the Plastic clay, 278
-- on tertiary outliers on chalk hills,
283
-- on the former continuity of the Lon.
don and Hampshire basins, 283
-- on valleys of elevation, 305, 307,
308
Budoshagy, rent exhaling sulphureous vapours
in the mountain of, 223
Bufadors, jets of air from subterranean
caverns called, 190
Bulimus montanus drifted from the Alps
into the Mediterranean, 48
Buried cones on Etna, sections of, 88
Burton, Mr. J., his discovery of tertiary
strata on the western borders of the
Red Sea, 135

Cadibona, section of the fresh-water formations
of -- see wood-cut No. 55, 221
-- lignites of, remains of an anthracotherium
found in, 222
Caernarvonshire, tertiary strata of, 135
Caesar, volcanos of Auvergne not men
tioned by, 269
Cairo, green Band containing shells at, 211
Calabria, recent tertiary strata of, 22
-- effects of the earthquake of 1783,
142, 319
Calais, ripple marks formed by the winds
on the dunes near-see wood-cut No.
36, 176
Calanna, lava of Etna turned from its
course by the hill of-see wood-cut No.
18, 86
-- description of the valley of, 85, 91
Calcaire grossier, alternation of the Plastic
clay and, 244
-- number of fossil shells of the, 245
-- abundance of cerithia in the, 245
-- alternates with fresh-water limestone
at Triel, 246
-- manner in which it was deposited,
246
-- in part destroyed when the upper
marine strata were formed, 248
-- abundance of microscopic shells in
the, 250
-- Palaeotherium and fresh-water shells
in, 252
Calcaire siliceux of the Paris basin, 246
-- alternates with calcaire grossier at
Triel, 246
-- how formed, 246
Calcareous grit and peperino, sections of
-- see diagrams Nos. 9 and 10, 72
Caltagirone, blue shelly marl of, 66, 67
-- fossil shells from-see list, Appendix
11, 55
Caltanisetta, dip of the tertiary strata at,
74
-- list of fossil shells from, -Appendix
II., 54
Cambridgeshire, great line of chalk escarpment
from, to Dorsetshire, 315
Campagna di Roma, age of the volcanic
rocks of the, 183
Campania, tertiary formation of, 118
-- comparison of recorded changes in,
with those commemorated by geological
monuments, 118
-- age of the volcanic and associated
rocks of, 126
-- external configuration of the country
how caused, 127
-- affords no signs of diluvial waves,
128
Canadian lakes, changes which would take
place in the Gulf of St. Lawrence if
they were filled up, 28
Cantal, fresh-water formations of, 236
-- fresh-water limestone and flints resembling
chalk in the, 237
-- proofs of the gradual deposition of
marl in the, 239
Cape Wrath, granite veins of-see woodcuts
Nos. 85 and 86, 354
Capitol, hill of the, a deposit of calcareous
tufa found on the, 138
Capo Santa Croce, shelly limestone resting
on lava at, 68
Capra, flowing of the lavas of 1811 and
1819 round the rock of -- see wood-cut
No. 21, 92
-- traversed by dikes, 92
Carboniferous series, 326
Carcare, tertiary strata of -- see wood-cut
No. 55, 207, 222
-- fossil shells of, 211
Cardona, rock salt of, its relative age, 333
Casamicciol, shells found in stratified tuff
at, 126
Caspian Sea, level of the, 29, 271
Castell de Stolles, ravine excavated in lava
opposite the, 189
Castell Follitt, extent of the lava stream of
-- see map, wood-cut No. 43, 184
-- section of lava cut through by river
at -- see wood-cut No. 46, 189, 190
Castello d'Aci, 81
Castrogiovanni, section of the Val di Noto
series at -- see diagram No.5, 64
-- hill of, its height, 66
-- capped by the Val di Noto limestone,
66
-- fossil fish found in gypseous marls
at, 67
-- list of fossil shells from Appendix
II., 55
Castelgomberto, fossil shells of-see Table,
Appendix J.
Catalonia, volcanic district of, 183
-- extent of the volcanic region of-see
map, wood-cut No. 43, 184
-- volcanic cones and lavas of -- Clee
Frontispiece), 185
-- ravines, excavated through lava in,
188, 189
-- age of the volcanos of, 191
-- superposition of rocks in the volcanic
district of-see wood-cut No. 47,
192
Catania, volcanic conglomerates forming
on the beach at, 73
-- plain of, 75, 76
-- marine formation near, 78
Catastrophes, remarks on theories respecting,
6, 33
Catcliff, Little, section of part of, showing
the inclination of the layers in opposite
directions -- see wood-cut No. 33, 175
Cavalaccio, Monte, shells procured from
the tuffs of, 79
Caves in Sicily, osseous breccias found in,
139
-- perforated in the interior by lithodomi,
140, 141
-- Australian, bones of marsupial animals
in, 143
Cavo delle Neve, hollow in Ischia called
the, 127
-- ancient sea-beach seen near, 127
Celient, lava current of -- see map, woodcut,
No 43, 184
-- section above the bridge of, -- see
wood-cut No. 45, 188
Central France, volcanic rocks of, 224,
257
-- fresh-water, formations of, 225
-- analogy of the tertiary deposits
of, to those of the Paris basin, 241,
247
-- valleys of, how formed, 319
Cer, valley of the, sections of foliated
marls in the, 239
Ceret and Boulon, dip of the tertiary strata
between, 170
Cerithia, abundance of in the calcaire gros.
sier, 245
Chabriol, M., on the fossil mammalia of
Mont Perrier, 218
Chadrat, pisolitic limestone of, 232
Chalk, protruded masses of in the crag
strata -- see wood-cuts Nos. 41 and 42,
179, 180
--English tertiary strata, conformable
to the, 282
-- deep indentations filled with sand,
&c., on its surface, 282
-- tertiary outliers on, 283
-- fissure in the, filled with sand near
Lewes, 283
-- and upper green sand of the Weald
valley, 286
-- escarpments of the Weald valley,
once sea -- cliffs-see wood-cuts Nos. 65
and 66, 289, 290, 291
-- why no ruins of, on the central district
of the Weald, 295
-- of the North and South Downs, its
former continuity, 303
-- the alternative of the hypothesis
that it was once continuous considered,
304
-- valleys and furrows in the, how
caused, 311
-- cliffs, rapid waste of on Sussex
coast, 311
-- greatest elevation attained by it in
England, 314
-- great line of escarpment formed by
the, through the central parts of England,
315
-- nearly all the land in Europe has
emerged since the deposition of the,
330
-- has been elevated at successive periods,
331
-- converted into marble by trap dike
in Antrim, 369
Chalk-flints, analysis of, 238
Chamalieres, near Clermont, section at,
228
Chambon, lake of, formed by the lava of
the Puy de Tartaret, 264
Chamouni, glaciers of, 150
Champheix, tertiary red marls of, 229
Champoleon in the Alps, strata altered
near, 371
Champradelle, section of vertical marls at,
-- see wood-cut No. 57, 231
Chili, Newer Pliocene marine strata at
great heights in, 130
Christie, Dr. T., his account of the Cave
of San Ciro, 140
-- on caverns in Mount Beliemi, Sicily,
143
Cirque of Gavarnie, in the Pyrenees, 88
Cisterna on Etna, formed by a subsidence
in 1792, 96, 129
Classification of tertiary formations in chronological
order, 45
Clay-slate, lamination of, in the Pyrenees
-- see wood-cut No. 89, 366
-- may be altered into shale, 373
-- convertible into hornblende schist,
373
Clermont, section of littoral deposits near,
228
-- section of vertical marls near-see
wood-cut No. 57, 231
-- alternations of volcanic tuff and
fresh-water limestone near, 258
Clift, Mr., on the bones of animals from
Australian caves, 144
Climate, effects of changes of, on species,
44
Coal reduced to cinder by trap dike, 370
Colle, fresh-water formation of, 137
-- fossil shells of living species in the,
138
Comb Hurst, hills of, 279
Come, lava current of, 186
Conception Bay, fossil shells of recent species
found at great heights in, 130.
Conglomerate, tertiary, of Nice, 167
-- now formed by the rivers near Nice,
168, 169
-- time required for the formation of
great beds of, 170
Conglomerates, volcanic, of the Val di Noto,
73
-- now forming on the shores of Catania
and Ischia, 73
Contemporaneous origin of Rocks, how
determined, 37
Contemporaneous, remarks en the term, 52
Continents, position of former, 328, 330
Contortions in the Newer Pliocene strata
in the Isle of Cyclops-see wood-cut
No. 15, 80
Conybeare, Rev. W. D., on the English
crag, 19
Conybeare, Rev. W. D., on the thickness
of the London clay, 279
-- on the organic remains of the London
clay, 280
-- on indentations in the chalk near Rochester,
282
-- on the transverse valleys of the North
and South Downs, 298
-- on the former continuity of the chalk
of the North and South Downs, 303
-- his objection to the theory of M. E.
de Beaumont, 348
Coomb, view of the ravine called the, near
Lewes -- see wood-cut No. 75, 301
Coquimbo, parallel roads of, 131
Corals standing erect among igneous and
aqueous formations at Galieri, 73
Cornwall, granite veins of-- see wood-cut
No. 87, 355, 370
-- argillaceous schist, containing organic
remains in, 376
Costa de Pujou, structure of the hill of -- see
frontispiece, 186
Corstorphine hills, parallel grooves on
their summits, how formed, 147
Cotentin, tertiary formation of the, 276
Coudes, tertiary red marl and sand-stone of,
like 'new red sand-stone, ' 229
Couze, river, lake formed by the filling up
of its ancient bed by lava, 264
Crag of England, organic remains of the, 19
-- its relative age, 17l
-- number of shells found in the, 171
-- its mineral composition, 17l
-- relative position of the -- see diag.
No. 30, 172
-- lacustrine deposits resting on the, 173
-- forms of stratification of the-see
wood-cuts 173, 174, 175
-- dip of the strata of the, 174, 175
-- comparison between the Faluns of
Touraine and the, 203
-- derangement in the strata of these
wood-cuts, 177
-- passage of, into alluvium, 181
-- its resemblance to formations now in
progress, 177, 182
-- proportion of living species in the fossil
shells of the-see Appendix I., p. 47
-- number common to Italy and the, ib.
47
-- number common to Sicily and the, ib.
47
-- number common to Italy, Sicily, and
the, ib. 47
-- geographical distribution of the living
species found in the, ib. 47, 51
Craters, volcanic, of the Eifel, how formed,
196
Creta, argillaceous deposit called, 67, 76
-- resting on columnar lava in the Isle
of Cyclops-see wood-cut No. 14, 79
Crocodile of the Ganges found in both salt
and fresh water, 330
Croizet, M., on extinct quadrupeds of
Mount Perrier, 218
-- on alluviums of different ages in
Auvergne, 267
Cromer, bent strata of loam in the cliffs
near -- see wood-cut No. 37, 178
Crowborough hill, height of, 288
-- thickness of strata removed from
the summit of, 313
Cruckshanks, Mr. A., on distinct lines of
ancient sea-cliffs on the coast of Peru,
130
Cuckmere, transverse valley of the, 298, 299
Curtis, Mr. J., on the fossil insects of Aix,
in Provence, 277
Cussac, bones of extinct quadrupeds in
alluvium under lava at, 219
Cutch, changes caused by the earthquake
of 1819 in, 104, 249, 318
Cuvier, M., on the mammiferous remains
of the Upper Val d'Arno, 221
-- on the tertiary strata of the Paris
basin, 16, 247, 243
--- on the fossil organic remains of
the Paris basin, 253
Cyclops, view of the island of, in the Bay
of Trezza -- see wood-cut No. 14, 79
-- its height, &c., 79
-- stratified marl resting on columnar
lava in the-see wood-cut No. 14, 79
Cypris, abundance of the remains of, in
the fresh-water strata of Auvergne, 230
-- habits of the living species of, 230

Darent, transverse valley of the, 298, 299
Daubeny, Dr., on the Val di Noto limestone,
66
-- on the volcanic region of Olot, in
Catalonia, 184
-- on the volcanic district of the Lower
Rhine and Eifel, 201
-- on the age of the Auvergne volcanos,
269
D'Aubuisson, on the appearance of some
of the Auvergne lavas, 94
Daun, lake-craters of the Eifel seen near,
195
Dax, tertiary formations of, 20, 206
-- section of tertiary strata overlying
the chalk near, -- see diag. No. 51, 207
--section of inland cliff near-see woodcut
No. 53, 210
-- fossil shells of-see tables Appendix I.
De Beaumont, M. Elie, on the cause of the
historical deluge, 148, 272
-- his theory of the contemporanous
origin of parallel mountain chains con
sidered, 337
-- his proofs that different chains were
raised at different epochs, 340
De Beaumont, M. Elie, objections to the
theory of, 341
-- on modern granite of the Alps, 358
De Candolle on the longevity of trees, 99
De la Beche, Mr., on M. Elie de Beaumont's
theory, 347
Delta, of the Niger, size of the, 329
-- of the Nile, preyed on by currents, 28
-- of Rhone, in lake of Geneva, 27
De Luc, on the deluge, 271
Deluge, on the changes caused by the, 270
-- M. Elie Beaumont, on the cause
of the historical, 148
Denudation, effects of, 30, 32
-- of the Valley of the Weald, 285
Deposition, sedimentary, shifting of the
areas of, 26
Descartes, 97
Deshayes, M., his comparison of the fossil
shells of Touraine, S. E. of France,
Piedmont and Vienna, 21
-- his tables of fossil shells, 49-see
Appendix I.
-- on the shells of the Val di Noto,
series, 65, 67
-- on shells of the sub-Etnean beds, 79
-- on the fossil shells of Ischia, 126
-- on the fossil shells of the Antilles,
133
-- on the fresh-water shells of Colle,
138
-- on the fossil shells of the Crag, 171
-- on the limestone of Blaye, 208
-- on the fossil shells of Volhynia and
Podolia, 215
-- on the fossil shells of Hungary, 223
-- on the abundance of Cerithia in the
Paris basin, 245
-- on the changes which the Cardium
porulosum underwent during its existence
in the Paris basin, 250
-- on the microscopic shells of the Paris
basin, 251
-- on the fossil shells of the Netherlands,
276
-- on the number of shells common
to the Maestricht beds, chalk, and upper
green sand, 325
-- on the distinctness of the secondary
and tertiary fossil shells, 327
-- on the secondary fossil shells of
the Pyrenees, 343
Desmoulins, M. Ch., on the Eocene deposits
of the environs of Bordeaux, 209
Desnoyers, M., on the organic remains of
the Faluns, 205
-- on the tertiary formations of Touraine,
20, 203
-- on the resemblance of the English
Crag and the Faluns of the Loire,
204
Desnoyers, M., on the fossil organic remains
of the Orleanais, 219
-- on the alternation of the plastic
clay and calcaire grossier in the Paris
basin, 244
-- on the tertiary formations of the Cotentin,
276
-- on the marine tertiary strata near
Rennes, 276
Devil's-dyke, view of the chalk escarpment
of the South Downs, taken
from the -- see wood-cut No. 65, 290
Diagonal stratification of the Crag strata -- see
wood-cuts, 174, 175
-- cause of this arrangement, 176
Dikes, intersecting limestone, 69
-- traversing peperino near Palagonia,
-- see diagrams Nos. 6 and 7, 69
-- on the summit of the lime-stone
platform, Val di Noto, 70
-- off tuff or peperino, how formed,
70
-- changes caused in argillaceous strata
by, 70
-- on Etna, their form, origin, and composition,
90
-- at the base of the Serra del Solfizio
-- see wood-cut, No. 19, 90
-- changes caused by, in the escarpment
of Somma, 91
-- in the Val del Bove, as seen from
the summit of Etna -- see wood-cut No.
22, 93
-- some caused by the filling up of
fissures by lava, 122, 123
-- of Somma -- see wood-cut No. 25,
122
-- cause of the parallelism of their opposite
sides, 122
-- varieties in their texture, 124
-- volcanic, in Madeira, 134
-- strata altered by, 368
Diluvial theories, 270
Diluvial waves, whether there are signs of
their occurrence on Etna, 101
-- no signs of, in Campania, 128
Dip and direction of the tertiary strata of
Sicily, 73
-- of the marine strata at the foot of
Etna, 78
Dominica, alternations of coral and lava
in, 133
Dorsetshire, valleys of elevation in, 308
Dorsetshire and Cambridgeshire, great line
of chalk escarpment between, 315
Doue, M. Bertrand de, on the fossil mammiferous
remains of Velay, 219
-- on the lacustrine deposits of Velay,
235, 236
-- on the igneous rocks of Velay,
262
Doue, M. Bertrand de, on Auvergne alluviums
under lava, 267
Du Bois, M., on the tertiary strata of, Vol.
hynia and Podolia, 215
Dufrenoy, M., on the limestone of Blaye,
near Bordeaux, 209
-- on the hill of Gergovia, 258
-- on the age of the red marl and rocksalt
of Cardona, 333
Durance, river, land-shells brought from
the Alps into the Rhone by the, 48
Dunwich, thickness of the crag strata in
the cliffs near, 172
Dunwich, dip of the crag strata in a cliff
between Mismer and -- see wood-cut
No. 33, 175
Dunes, near Calais, ripple marks formed
by the winds on the -- see wood-cut, No.
36, 176

Earthquake, Olot destroyed by, in 1421,
191
-- of Cutch, effects of the, 104, 249,
318
Earthquakes, their effects on the excava
tion of valleys, 113
-- during the Eocene period, 312
Earth's crust, signs of a succession of former
changes recognizable in, 1
-- arrangement of the materials composing
the, 8
Earth's surface may be greatly changed in
one part while an adjoining tract re
mains stationary, 128
East Indian Archipelago, tertiary formations
of the, 133
Ehrenhausen, coralline limestone of the
hills of, 214
Eichwald, M., on the tertiary deposits of
Volhynia and Podolia, 215
Eifel, volcanos of the, 193
-- map of the volcanic district of the -- see
wood-cut No. 48, 194
--lake-craters of the -- see wood-cut,
No. 49, 195
--trass of the, and its origin, 197
-- age of the volcanic rocks of the, 199
Elevation of land, how caused, 105
Elevation, proofs of successive, 111
Elsa, valley of the, fresh-water formations
of, 137
England, tertiary strata of, 19, 135, 171,
284
-- comparison between the tertiary
strata of Paris and those of, 282
-- tertiary strata of, conformable to the
chalk, 282
-- origin of the tertiary strata of, 284
-- great line of chalk escarpment
through the central parts of, 315
-- elevation of land on the east coast of,
since the Older Pliocene period, 316
England, elevation of land gradual in the
S.E. of, 318
-- on the excavation of valleys in the
S.E. of, 319
Enza, river, nature of the sediment deposited
by the, 161
Eocene period, derivation of the term, 55
-- proportion of living species in the
fossil shells of the, 55
-- position of the beds referrible to
this era -- see diagrams Nos. 3 and 4,
20, 21
-- geographical distribution of the recent
species found in the, 55
-- mammiferous remains of the, 59
-- fresh-water formations of the,
225
-- marine formations of the, 241
-- our knowledge of the physical geography,
fauna and flora of the, considerable,
254
-- volcanic rocks of the, 257
-- map of the principal tertiary basins of
the-see wood-cut No. 62, 275
-- earthquakes during the, 312
-- alluviums of the, 311
-- chasm between the newest second
ary formations and those of the, 328
-- great volume of hypogene rocks
formed since, 381
-- number of species of fossil shells
common to different formations referri
ble to the, Appendix I., p. 49
-- number of living species in the fossil
shells of the, ib., 50
-- number common to the Pliocene,
Miocene, and, ib., 50
-- geugraphical distribution of the living
species found in the, ib., 51
Eocene strata in the Bordeaux basin, 208
-- its relative position-see wood-cut
No. 52, 209
Epomeo, shells found in volcanic tuff near
the summit of, 126
Erratic blocks of the Alps, 148
-- transported by ice, 149
Escarpments, manner in which the sea
destroys successive lines of, 111, 292
Escarpments of the chalk in the Weald
valley, once sea-cliffs -- see wood-cuts,
Nos. 65 and 66, 289, 291
Estuary deposits, arrangement of, 9
Eternity of the earth, or of present system
of changes not assumed in this work,
383
Etna, marine and volcanic formations at
its base, 75
-- view of, from the limestone platform
of Primosole-see diagram No. 11, 75
-- connexion of the strata at its base
with those of the Val di Noto -- see
diagram No. 12, 76
Etna, southern base of, 77
-- recent shells in clay at the foot of, 77
-- dip of the marine strata at the base
of, 78
-- eastern side of, 78
-- shells in tuffs and marls on the east
side of, 79
-- lavas of the Cyclopian isles, not currents
from, 81
-- internal structure of the cone of, 83
--great valley on the east side of -- see
wood-cut No. 17, 83
-- lateral eruptions of, 84
-- manlier of increase of the principal
cone of, 84
-- sections of buried cones on, 88
-- form, composition, and origin of the
dikes on, 90
-- veins of lava on -- see wood-cut No.
20, 91
-- view from the summit of, into the
Val del Bove -- see wood-cut No. 22,
93
-- subsidences on, 96
-- antiquity of the cone of, 97
-- whether signs of diluvial waves are
observable on, 101
-- list of fossil shells from the flanks
of -- Appendix II., p. 53,
Europe, newest tertiary strata of, 22
-- large portions of, submerged when
the secondary strata were formed, 23
-- almost all the land in, has emerged
since the deposition of the chalk, 330
European tertiary strata, successive origin
of the, 18
European alluviums in great part tertiary,
150
Excavation of valleys, 319

Faluns of Touraine, 203
-- comparison between the English
crag and the, 203, 204
-- were formed in a shallow sea, 204
-- organic remains of the, 204, 206
Fasano, escarpment of marine strata seen
near, 78
Fault in the cliff-hills near Lewes -- see
section, wood-cut No. 76, 301
Finochio, view of the rock of, with the
lavas of 1811 and 1819 flowing round
it -- see wood-cut No. 21, 92
Firestone of the Weald Valley, 286
-- terrace formed by the harder beds
of -- see wood-cut No. 67, 291, 292
Fish, skeletons of, by no means frequent
in a fossil state, 47
-- fossil, of Castrogiovanni, 67
Fitton, Dr., on the secondary rocks of the
Valley of the Weald, 286
-- on the denudation of the Weald Val
ley, 289
Fitton, Dr., on faults in the strata of the
Forest ridge, 293
-- on a line of vertical and inclin
ed strata from the Isle of Wight to
Dieppe, 315
-- an ammonite found in the Maestricht
beds by, 325
-- on the extent and thickness of the
Wealden, 329
-- on the delta of the Niger, 3.29
Fiume Salso, in Sicily, 252
Fleming, Dr., on the effects of the deluge,
271
Flinty slate, slate-clay of the lias, converted
into, by trap dike, 370
Flood, supposed effects of the, 270
-- hypothesis of a partial, 270
Floridia, schistose and arenaceous limestone
of, 66
Fluvia, river, ravines in lava excavated by,
186, 189
Forest ridge of the Weald Valley, 293
-- faults in the strata of the, 293
-- thickness of masses removed from
the, 313
Formations, causes of the superposition of
successive, 26
-- universal, remarks on the theory
of, 38
-- new subdivisions of the tertiary,
52
Fossa Grande, section of Vesuvius seen in,
84
Fossilization of plants and animals partial,
31
Fossils, distinctness of the secondary and
tertiary, 327
Fresh-water deposits, secondary, why rare,
330
Fuveau, in Provence, tertiary strata of,
276

Gabel Tor, volcano of, 136
Galieri, a bed of corals found standing
erect among igneous and aqueous formations
at, 73
Ganges, the crocodile of the, found both
in fresh and salt water, 330
Gannat, fresh-water limestone of, 232
Garnets, in altered shale, 369
Garrinada, hill of, described -- (see frontispiece, )
187
Gavarnie, cirque of, 88
-- lamination of clay-slate near -- see
wood-cut No. 89, 366
Gault of the Valley of the Weald,
286
-- valley formed at its out-crop, 292
-- forms an escarpment towards the
Weald clay, 293
Gemunden Maar, view of the-see wood
cut No. 49, 195
Geneva, lake of, advance of the delta of
the Rhone in, 27
-- change which will take place in the
distribution of sediment when it is filled
up, 27
Genoa, height of the tertiary strata above
the sea at, 165, 166
-- position of the strata -- see diagram
No. 28, 166
Geological periods, their distinctness may
arise from our imperfect information, 56
Gergovia, hill of, alternation of volcanic
tuff and fresh-water marls in the, 258
-- section of, 259
-- intersected by a dike of basalt-see
wood-cut, No. 60, 259
Giacomo, St., valley of, described, 84, 85,
91
Gillenfeld, description of the Pulvermaar
of, 197
Girgenti, section at-see diagram No.5,
64
-- shells found in the limestone of, 65
-- dip of the tertiary strata at, 74
-- list of fossil shells from-Appendix
II., p.54
Gironde, tertiary strata or the basin of the,
206
Glaciers of Savoy, great quantities of rock
brought down by the, 149
Glen Roy, parallel roads of, 131
Glen Tilt, junction of limestone and granite
in -- see wood-cut No. 88, 356
Gly, river, tertiary strata in the valley of
the, 170
Gneiss, mineral composition of, 365, 367
-- passage of, into granite, 367, 372
-- was originally deposited from water,
367
-- whence derived, 373
Gozzo degli Martiri, dikes intersecting
limestone at, 69
-- view of the valley of -- see wood-cut
No. 23, 110
Grammichele, beds or incoherent yellow
sand with shells found near, 66
-- bones of the mammoth found in
alluvium at, 151
Grampians, granite veins of the, 357
Granada, tertiary strata of, 170
Granite, junction of limestone and, in Glen
Tilt -- see wood-cut No. 88, 356
-- formed at different periods, 13, 357
-- passage from trap into, 361
-- origin of, 12, 363
-- passage of gneiss into, 367, 372
-- changes produced by its contact
with strata of lias and oolite in the Alps,
371
Granite veins, their various forms and
mineral composition -- see wood-cuts,
Nos. 85, 86, 87, and 88, 353, 356, 370
Gravesend, deep indentations in the chalk
filled with sand, gravel, &c., near, 282
Greywacke, 377
-- of the Eisel, 194
-- age of the rocks termed, 327
Greenough, Mr., on fossil shells from the
borders of the Red Sea, 136
Grifone, Monte, caves containing the re.
mains of extinct animals in, 141
Grit, calcareous, and peperino, sections of
-- see diagrams Nos. 9 and 10, 72
Grooved surface of rocks, how formed,
147
Grosoeil, near Nice, tertiary strata found
at, 135
Guadaloupe, active volcanos in, 133
Guidotti, Signor, on the shells of the gyp~
sum of Monte Cerio, 159
Gypseous marls containing fish found at
Castrogiovanni, 63, 67
Gypsum, and marls, of the Paris basin, 247
-- bones of quadrupeds, &c., in, 251
-- on the entire absence of marine re
mains in the, 252
-- of St. Romain on the Allier, 233
-- beds of, interstratified with the sub-
Apennine marls, 159
-- unaltered shells in the, 159
Gyrogonites, abundant in the fresh-water
formations of the Paris basin, 250

Hall, Sir James, his experiments on rocks,
124
-- on the grooved summits of the Cor
storphine hills, 147
Hall, Capt. B., on the parallel roads of
Coquimbo, 131
-- on vertical dikes of lava in Madeira,
134
-- on the veins traversing the Table
Mountain, Cape of Good Hope, 354
Hamilton, Sir W., his account of the erup
tion of Vesuvius in 1779, 122
Hampshire basin, tertiary formations of the
18, 280
--mammiferous remains of the, 280, 281
-- on the former continuity of the London
and, 283
Happisborough, diagonal stratification of
the crag strata near -- see wood-cut No.
32, 174
Hartz mountains, geological and geographical
axes of the, 346
Hastings sands, their composition, 286
-- anticlinal axis formed by the, 287
Haute Loire, fresh-water formation of the,
235
Headen Hill, section of, 281
Heat, its influence on the consolidation of
strata, 334
Hebrides, age of the volcanic rocks of the,
336
Heidelberg, shells found in the loess at,
152
-- loess and gravel alternating at, 153
-- granites of different ages near, 357
Henslow, Professor, on the changes caused
by a volcanic dike in Anglesea, 368
Hibbert, Dr., on the extinct volcanos of
the Rhine, 197, 201
-- on the loess of the valley of the
Rhine, 151
-- on the mammiferous remains of
Velay, 219
Highbeach, in Essex, height of the London
clay at, 312
Hoffmann, Professor, his examination of
Sicily, 63
-- on the limestone of Capo Santa Croce,
68
-- on the new island of Sciacca, 71
-- on the Val del Bove, 88
-- on cave deposits in Sicily, 139, 140,
141
Honduras, recent strata of the, 133
Hornblende schist, altered clay or shale,
373
Horner, Mr. Leonard, his map of the volcanic
district of the Eifel and Lower
Rhine-see wood-cut No. 48, 194
-- on the geology of the Lower Rhine
and Eifel, 201
Hugi, M., on secondary strata altered into
gneiss in the Alps, 372
-- on modern granite in the Alps, 358
Human remains now becoming imbedded
in osseous breccias in the Morea, 144
Humboldt, on the depression of a large
part of Asia, below the level of the sea,
29
Hundsruck, beds and veins of quartz found
in the mountains of the, 201
Hungary, tertiary formations of, 212
-- age of the tertiary strata of, 215
-- volcanic rocks of, 222
-- age of the igneous rocks of, 223
Hutton, his opinion as to altered sedimentary
rocks, 382
Huttonian hypothesis of the origin of
gneiss, 366
Hypogene, term proposed as a substitute
for primary, 374
-- formations, no order of succession
in, 375
-- rocks, their identity of character in
distant regions, 376
-- produced in all ages in equal quantities,
377
-- their relative age, 377
-- volume of, formed since the Eocene
period, 381

Icebergs, rocks transported by, deposited
wherever they are dissolved, 149, 150
Idienne, volcanic mountain of, 252
Indusial limestone of Auvergne, 232
Inkpen Hill, the highest point of the chalk
in England, 314
Inland cliff near Dax -- see wood-cut No.
53, 209
Inland cliffs on East side of Val di Noto,
111
Insects, fossil, of Aix, 277
Ischia, volcanic conglomerates now in
progress on the shores of, 73
-- fossil shells of recent species found
at great heights in, 126
-- external configuration of, how caused)
127
-- list of fossil shells from-Appendix
11., 57
Isle of Bourbon, a volcanic eruption every
two years in, 363
Isle of Cyclops, in the bay of Trezza, view
of -- see wood-cut No. 14, 79
-- its height, &c., 79
-- stratified marl resting on columnar
lava in the -- see wood-cut No. 14, 79
-- contortions in the newer Pliocene,
strata of-see wood-cut No. 15, 80
-- divided into two parts by a great
fissure, 80
-- newer Pliocene strata invaded by
lava in -- see wood-cut No. 16, 81
-- lavas of, not currents from Etna, 81
Isle of Purbeck, traversed by a line of vertical
or inclined strata, 315
Isle of Wight, geology of the, 18
-- fall of one of the Needles of the, into
the sea in 1772, 181
-- fresh-water strata of the, 280
-- mammiferous remains of the, 281,
317
-- vertical strata of the, 315
Italy, tertiary strata of, 18
-- age of the volcanic rocks of, 183
-- number of living species in the fossil
shells of -- see Appendix 1., 47
-- number of those common to Sicily
and, ib. 47
-- number common to the Crag and,
ib.47
-- number common to Sicily, the
and, ib. 47

Jack, Dr., on the geology of the island of
Pulo Nias, 134
Jamaica, fossil shells of recent species
from, in the British Museum, 133
Java, subsidence of the volcano of Papandayang,
in the island of, 96
-- vegetation destroyed by hot sulphuric
water from a mountain in, 252
Jobert, M., on the extinct quadrupeds of
Mont Perrier, 218
-- on the hill of Gergovia, 258
Jobert, M., on the different ages of Auvergne
alluviums, 267
Jorullo, time for which the lava of, retained
its heat, 363
Jura, erratic blocks of the, 148

Kaiserstuhl, volcanic hills in the plains of
the Rhine, 152
-- covered nearly to their summits with
loess, 152
Katavothrons of the plain of Tripolitza now
filling up with osseous breccias, 144
Kater, Capt., on recent deposits near
Ramsgate, 182
Keferstein, M., his objections to M. de
Beaumont's theory, 347
Kingsclere, valley of, ground plan of the
-- see wood-cut No. 78, 305
-- section across the, from North to
South -- see wood-cut No. 79, 305
-- section of the, with the heights on a
true scale-see wood-cut No. 80, 306
-- anticlinal axis of the, 306
-- proofs of denudation in the, 307
Killas of Cornwall, 370

Laach, lake-crater of, 197
Lacustrine deposits overlying the crag -- see
diagram No. 30, 173
Lake Aidat, formed by the damming up of
a river by lava, 269
Lake-craters of the Eifel-see wood-cuts
Nos. 49 and 50, 195, 196
-- how formed, 196
Lakes, arrangement of deposits in, 8
Lake Superior, recent deposits in, analogous
to those of the Eocene lakes in
Anvergne, 230
-- nature of the recent deposits in, 334
-- the bursting of its barrier would cause
an extensive deluge, 270
Lamarck, his list of the fossil shells of the
Paris basin, 156
La Motta, valleys excavated through blue
marl capped with columnar basalt at, 77
-- volcanic conglomerate of-see diagram
No. 13, 77
--relative age of the basalts of, 82
Lancashire, tertiary strata of, 135
Land, elevation of, caused by subterranean
lava, 105
Land-shells drifted from the Alps into the
Mediterranean, 48
Landers, on the delta of the Niger, 330
Landes, tertiary strata of the, 206
La Roche, section of the hill of, 229
Las Planas, lava current of, 189
La Trinita, near Nice, fossil shells of, 168
Lauder, Sir T. D., on the parallel roads of
Glen Roy, 131
Lava, a bed of oysters between two currents
of, at Vizzini, 73
Lava, columnar, stratified marl resting on,
in the Isle of Cyclops -- see wood-cut
No. 14, 79
-- minerals in cavities of, 81
-- veins of, on Etna, 91
--great length of time which it requires
to cool, 363
Lava streams solid externally while in mo
tion, 86
Lavas of the Cyclopian isles not currents
from Etna, 81
Lavas and breccias of the Val del Bove, 93
Lavas excavated by rivers in Catalonia,
186, 189
Lavas and alluviums of different ages in
Auvergne -- see wood-cut No. 61, 266
La Vissiere, fresh-water limestone covered
by volcanic rocks at, 263
-- faults in the limestone at, 263
Leeward Islands, geology of the, 132
Le Grand d'Aussi, M., on alluviums under
lava in Auvergne, 267
Leith Hill, height of, 293
Lentini, volcanic pebbles covered with
serpulae in the limestone near, 73
-- dip of the strata at, 74
-- valleys near, their origin, 111
Leonhard, M., on the loess of the valley of
the Rhine, 151
-- on the volcanic district of the Lower
Rhine, 201
-- on granites of different ages near
Heidelberg, 357
Lewes, fissures in the chalk filled with
sand near, 283
-- view of the ravine called the Coomb
near -- see wood-cut No. 75, 301
--fault in the cliff-hills near-see woodcut
No. 76, 301
admin
Site Admin
 
Posts: 28480
Joined: Thu Aug 01, 2013 5:21 am

PreviousNext

Return to Science

Who is online

Users browsing this forum: No registered users and 1 guest