Chapter 75

MINERAL VEINS.

Different Kinds of mineral Veins. — Ordinary metalliferous Veins or Lodes. — Their frequent Coincidence with Faults. — Proofs that they originated in Fissures in solid Rock. — Veins shifting other Veins. — Polishing of their Walls or “Slicken sides.” Shells and Pebbles in Lodes. — Evidence of the successive Enlargement and Reopening of veins. — Examples in Cornwall and in Auvergne. — Dimensions of Veins. — Why some alternately swell out and contract. — Filling of Lodes by Sublimation from below. — Supposed relative Age of the precious Metals. — Copper and lead Veins in Ireland older than Cornish Tin. — Lead Vein in Lias, Glamorganshire. — Gold in Russia, California, and Australia. — Connection of hot Springs and mineral Veins.

The manner in which metallic substances are distributed through the earth’s crust, and more especially the phenomena of those more or less connected masses of ore called mineral veins, from which the larger part of the precious metals used by man are obtained, are subjects of the highest practical importance to the miner, and of no less theoretical interest to the geologist.

On different Kinds of Mineral Veins.—The mineral veins with which we are most familiarly acquainted are those of quartz and carbonate of lime, which are often observed to form lenticular masses of limited extent traversing both hypogene strata and fossiliferous rocks. Such veins appear to have once been chinks or small cavities, caused, like cracks in clay, by the shrinking of the mass, during desiccation, or in passing from a higher to a lower temperature. Siliceous, calcareous, and occasionally metallic matters have sometimes found their way simultaneously into such empty spaces, by infiltration from the surrounding rocks. Mixed with hot water and steam, metallic ores may have permeated the mass until they reached those receptacles formed by shrinkage, and thus gave rise to that irregular assemblage of veins, called by the Germans a “stockwerk,” in allusion to the different floors on which the mining operations are in such cases carried on.

The more ordinary or regular veins are usually worked in vertical shafts, and have evidently been fissures produced by mechanical violence. They traverse all kinds of rocks, both hypogene and fossiliferous, and extend downward to indefinite or unknown depths. We may assume that they correspond with such rents as we see caused from time to time by the shock of an earthquake. Metalliferous veins referable to such agency are occasionally a few inches wide, but more commonly three or four feet. They hold their course continuously in a certain prevailing direction for miles or leagues, passing through rocks varying in mineral composition.

That Metalliferous Veins were Fissures.—As some intelligent miners, after an attentive study of metalliferous veins, have been unable to reconcile many of their characteristics with the hypothesis of fissures, I shall begin by stating the evidence in its favour. The most striking fact, perhaps, which can be adduced in its support is, the coincidence of a considerable proportion of mineral veins with _faults,_ or those dislocations of rocks which are indisputably due to mechanical force, as above explained (p. 87). There are even proofs in almost every mining district of a succession of faults, by which the opposite walls of rents, now the receptacles of metallic substances, have suffered displacement. Thus, for example, suppose _a a,_ Fig. 629, to be a tin lode in Cornwall, the term _lode_ being applied to veins containing metallic ores. This lode, running east and west, is a yard wide, and is shifted by a copper lode (_b b_) of similar width. The first fissure (_a a_) has been filled with various materials, partly of chemical origin, such as quartz, fluor-spar, peroxide of tin, sulphuret of copper, arsenical pyrites, bismuth, and sulphuret of nickel, and partly of mechanical origin, comprising clay and angular fragments or detritus of the intersected rocks. The plates of quartz and the ores are, in some places, parallel to the vertical sides or walls of the vein, being divided from each other by alternating layers of clay or other earthy matter. Occasionally the metallic ores are disseminated in detached masses among the vein-stones.

It is clear that, after the gradual introduction of the tin and other substances, the second rent (_b b_) was produced by another fracture accompanied by a displacement of the rocks along the plane of _b b._ This new opening was then filled with minerals, some of them resembling those in _a a,_ as fluor-spar (or fluate of lime) and quartz; others different, the copper being plentiful and the tin wanting or very scarce. We must next suppose a third movement to occur, breaking asunder all the rocks along the line _c c,_ Fig. 630; the fissure, in this instance, being only six inches wide, and simply filled with clay, derived, probably, from the friction of the walls of the rent, or partly, perhaps, washed in from above. This new movement has displaced the rock in such a manner as to interrupt the continuity of the copper vein (_b b_), and, at the same time, to shift or heave laterally in the same direction a portion of the tin vein which had not previously been broken.

Vertical sections of the mine at Huel Peever, Redruth, Cornwall. Fig. 629: Tin; Fig. 630: Copper; Fig. 631: Clay.

Again, in Fig. 631 we see evidence of a fourth fissure (_d d_), also filled with clay, which has cut through the tin vein (_a a_), and has lifted it slightly upward towards the south. The various changes here represented are not ideal, but are exhibited in a section obtained in working an old Cornish mine, long since abandoned, in the parish of Redruth, called Huel Peever, and described both by Mr. Williams and Mr. Carne.[1] The principal movement here referred to, or that of _c c,_ Fig. 631, extends through a space of no less than 84 feet; but in this, as in the case of the other three, it will be seen that the outline of the country above, _d, c, b, a,_ etc., or the geographical features of Cornwall, are not affected by any of the dislocations, a powerful denuding force having clearly been exerted subsequently to all the faults. (See p. 93.) It is commonly said in Cornwall, that there are eight distinct systems of veins, which can in like manner be referred to as many successive movements or fractures; and the German miners of the Hartz Mountains speak also of eight systems of veins, referable to as many periods.

Besides the proofs of mechanical action already explained, the opposite walls of veins are often beautifully polished, as if glazed, and are not unfrequently striated or scored with parallel furrows and ridges, such as would be produced by the continued rubbing together of surfaces of unequal hardness. These smoothed surfaces resemble the rocky floor over which a glacier has passed (see Fig. 106). They are common even in cases where there has been no shift, and occur equally in non-metalliferous fissures. They are called by miners “slicken-sides,” from the German _schlichten,_ to plane, and _seite,_ side. It is supposed that the lines of the striæ indicate the direction in which the rocks were moved.

In some of the veins in the mountain limestone of Derbyshire, containing lead, the vein-stuff, which is nearly compact, is occasionally traversed by what may be called a vertical crack passing down the middle of the vein. The two faces in contact are slicken-sides, well polished and fluted, and sometimes covered by a thin coating of lead-ore. When one side of the vein-stuff is removed, the other side cracks, especially if small holes be made in it, and fragments fly off with loud explosions, and continue to do so for some days. The miner, availing himself of this circumstance, makes with his pick small holes about six inches apart, and four inches deep, and on his return in a few hours finds every part ready broken to his hand.[2]

That a great many veins communicated originally with the surface of the country above, or with the bed of the sea, is proved by the occurrence in them of well-rounded pebbles, agreeing with those in superficial alluviums, as in Auvergne and Saxony. Marine fossil shells, also, have been found at great depths, having probably been ingulfed during submarine earthquakes. Thus, a gryphæa is stated by M. Virlet to have been met with in a lead-mine near Semur, in France, and a madrepore in a compact vein of cinnabar in Hungary.[3] In Bohemia, similar pebbles have been met with at the depth of 180 fathoms; and in Cornwall, Mr. Carne mentions true pebbles of quartz and slate in a tin lode of the Relistran Mine, at the depth of 600 feet below the surface. They were cemented by oxide of tin and bisulphuret of copper, and were traced over a space more than twelve feet long and as many wide.[4] When different sets or systems of veins occur in the same country, those which are supposed to be of contemporaneous origin, and which are filled with the same kind of metals, often maintain a general parallelism of direction. Thus, for example, both the tin and copper veins in Cornwall run nearly east and west, while the lead veins run north and south; but there is no general law of direction common to different mining districts. The parallelism of the veins is another reason for regarding them as ordinary fissures, for we observe that faults and trap dikes, admitted by all to be masses of melted matter which have filled rents, are often parallel.

_Fracture, Re-opening and Successive Formation of Veins._—Assuming, then, that veins are simply fissures in which chemical and mechanical deposits have accumulated, we may next consider the proofs of their having been filled gradually and often during successive enlargements.

Werner observed, in a vein near Gersdorff, in Saxony, no less than thirteen beds of different minerals, arranged with the utmost regularity on each side of the central layer. This layer was formed of two plates of calcareous spar, which had evidently lined the opposite walls of a vertical cavity. The thirteen beds followed each other in corresponding order, consisting of fluor-spar, heavy spar, galena, etc. In these cases the central mass has been last formed, and the two plates which coat the walls of the rent on each side are the oldest of all. If they consist of crystalline precipitates, they may be explained by supposing the fissure to have remained unaltered in its dimensions, while a series of changes occurred in the nature of the solutions which rose up from below: but such a mode of deposition, in the case of many successive and parallel layers, appears to be exceptional.

If a vein-stone consist of crystalline matter, the points of the crystals are always turned inward, or towards the centre of the vein; in other words, they point in the direction where there was space for the development of the crystals. Thus each new layer receives the impression of the crystals of the preceding layer, and imprints its crystals on the one which follows, until at length the whole of the vein is filled: the two layers which meet dovetail the points of their crystals the one into the other. But in Cornwall, some lodes occur where the vertical plates, or _combs,_ as they are there called, exhibit crystals so dovetailed as to prove that the same fissure has been often enlarged. Sir H. De la Beche gives the following curious and instructive example (Fig. 632), from a copper-mine in granite, near Redruth.[5] Each of the plates or combs (_a, b, c, d, e, f_) is double, having the points of their crystals turned inward along the axis of the comb. The sides or walls (2, 3, 4, 5 and 6) are parted by a thin covering of ochreous clay, so that each comb is readily separable from another by a moderate blow of the hammer. The breadth of each represents the whole width of the fissure at six successive periods, and the outer walls of the vein, where the first narrow rent was formed, consisted of the granitic surfaces 1 and 7.

Fig. 632: Copper lode, near Redruth, enlarged at six successive periods.

A somewhat analogous interpretation is applicable to many other cases, where clay, sand, or angular detritus, alternate with ores and vein-stones. Thus, we may imagine the sides of a fissure to be incrusted with siliceous matter, as Von Buch observed, in Lancerote, the walls of a volcanic crater formed in 1731 to be traversed by an open rent in which hot vapours had deposited hydrate of silica, the incrustation nearly extending to the middle.[6] Such a vein may then be filled with clay or sand, and afterwards re-opened, the new rent dividing the argillaceous deposit, and allowing a quantity of rubbish to fall down. Various metals and spars may then be precipitated from aqueous solutions among the interstices of this heterogeneous mass.

That such changes have repeatedly occurred, is demonstrated by occasional cross-veins, implying the oblique fracture of previously formed chemical and mechanical deposits. Thus, for example, M. Fournet, in his description of some mines in Auvergne worked under his superintendence, observes that the granite of that country was first penetrated by veins of granite, and then dislocated, so that open rents crossed both the granite and the granitic veins. Into such openings, quartz, accompanied by sulphurets of iron and arsenical pyrites, was introduced. Another convulsion then burst open the rocks along the old line of fracture, and the first set of deposits were cracked and often shattered, so that the new rent was filled, not only with angular fragments of the adjoining rocks, but with pieces of the older vein-stones. Polished and striated surfaces on the sides or in the contents of the vein also attest the reality of these movements. A new period of repose then ensued, during which various sulphurets were introduced, together with hornstone quartz, by which angular fragments of the older quartz before mentioned were cemented into a breccia. This period was followed by other dilatations of the same veins, and the introduction of other sets of mineral deposits, as well as of pebbles of the basaltic lavas of Auvergne, derived from superficial alluviums, probably of Miocene or even Older Pliocene date. Such repeated enlargement and re-opening of veins might have been anticipated, if we adopt the theory of fissures, and reflect how few of them have ever been sealed up entirely, and that a country with fissures only partially filled must naturally offer much feebler resistance along the old lines of fracture than anywhere else.

Cause of alternate Contraction and Swelling of Veins.—A large proportion of metalliferous veins have their opposite walls nearly parallel, and sometimes over a wide extent of country. There is a fine example of this in the celebrated vein of Andreasburg in the Hartz, which has been worked for a depth of 500 yards perpendicularly, and 200 horizontally, retaining almost everywhere a width of three feet. But many lodes in Cornwall and elsewhere are extremely variable in size, being one or two inches in one part, and then eight or ten feet in another, at the distance of a few fathoms, and then again narrowing as before. Such alternate swelling and contraction is so often characteristic as to require explanation. The walls of fissures in general, observes Sir H. De la Beche, are rarely perfect planes throughout their entire course, nor could we well expect them to be so, since they commonly pass through rocks of unequal hardness and different mineral composition. If, therefore, the opposite sides of such irregular fissures slide upon each other, that is to say, if there be a fault, as in the case of so many mineral veins, the parallelism of the opposite walls is at once entirely destroyed, as will be readily seen by studying Figs. 633 to 635.

Let _a b,_ Fig. 633, be a line of fracture traversing a rock, and let _a b,_ Fig. 634, represent the same line. Now, if we cut in two a piece of paper representing this line, and then move the lower portion of this cut paper sideways from _a_ to _a′_, taking care that the two pieces of paper still touch each other at the points 1, 2, 3, 4, 5, we obtain an irregular aperture at _c,_ and isolated cavities at _d, d, d,_ and when we compare such figures with nature we find that, with certain modifications, they represent the interior of faults and mineral veins. If, instead of sliding the cut paper to the right hand, we move the lower part towards the left, about the same distance that it was previously slid to the right, we obtain considerable variation in the cavities so produced, two long irregular open spaces, _f, f,_ Fig. 635, being then formed. This will serve to show to what slight circumstances considerable variations in the character of the openings between unevenly fractured surfaces may be due, such surfaces being moved upon each other, so as to have numerous points of contact.

Figs. 633, 634, 635: Lines of fracture traversing a rock.

Fig. 636: Nipped ores where the course of a vein departs from verticality.

Most lodes are perpendicular to the horizon, or nearly so; but some of them have a considerable inclination or “hade,” as it is termed, the angles of dip being very various. The course of a vein is frequently very straight; but if tortuous, it is found to be choked up with clay, stones, and pebbles, at points where it departs most widely from verticality. Hence at places, such as _a,_ Fig. 636, the miner complains that the ores are “nipped,” or greatly reduced in quantity, the space for their free deposition having been interfered with in consequence of the pre-occupancy of the lode by earthy materials. When lodes are many fathoms wide, they are usually filled for the most part with earthy matter, and fragments of rock, through which the ores are disseminated. The metallic substances frequently coat or encircle detached pieces of rock, which our miners call “horses” or “riders.” That we should find some mineral veins which split into branches is also natural, for we observe the same in regard to open fissures.

Chemical Deposits in Veins.—If we now turn from the mechanical to the chemical agencies which have been instrumental in the production of mineral veins, it may be remarked that those parts of fissures which were choked up with the ruins of fractured rocks must always have been filled with water; and almost every vein has probably been the channel by which hot springs, so common in countries of volcanoes and earthquakes, have made their way to the surface. For we know that the rents in which ores abound extend downward to vast depths, where the temperature of the interior of the earth is more elevated. We also know that mineral veins are most metalliferous near the contact of Plutonic and stratified formations, especially where the former send veins into the latter, a circumstance which indicates an original proximity of veins at their inferior extremity to igneous and heated rocks. It is moreover acknowledged that even those mineral and thermal springs which, in the present state of the globe, are far from volcanoes, are nevertheless observed to burst out along great lines of upheaval and dislocation of rocks.[7] It is also ascertained that all the substances with which hot springs are impregnated agree with those discharged in a gaseous form from volcanoes. Many of these bodies occur as vein-stones; such as silex, carbonate of lime, sulphur, fluor-spar, sulphate of barytes, magnesia, oxide of iron, and others. I may add that, if veins have been filled with gaseous emanations from masses of melted matter, slowly cooling in the subterranean regions, the contraction of such masses as they pass from a plastic to a solid state would, according to the experiments of Deville on granite (a rock which may be taken as a standard), produce a reduction in volume amounting to 10 per cent. The slow crystallisation, therefore, of such Plutonic rocks supplies us with a force not only capable of rending open the incumbent rocks by causing a failure of support, but also of giving rise to faults whenever one portion of the earth’s crust subsides slowly while another contiguous to it happens to rest on a different foundation, so as to remain unmoved.

Although we are led to infer, from the foregoing reasoning, that there has often been an intimate connection between metalliferous veins and hot springs holding mineral matter in solution, yet we must not on that account expect that the contents of hot springs and mineral veins would be identical. On the contrary, M. E. de Beaumont has judiciously observed that we ought to find in veins those substances which, being least soluble, are not discharged by hot springs—or that class of simple and compound bodies which the thermal waters ascending from below would first precipitate on the walls of a fissure, as soon as their temperature began slightly to diminish. The higher they mount towards the surface, the more will they cool, till they acquire the average temperature of springs, being in that case chiefly charged with the most soluble substances, such as the alkalies, soda and potash. These are not met with in veins, although they enter so largely into the composition of granitic rocks.[8]

To a certain extent, therefore, the arrangement and distribution of metallic matter in veins may be referred to ordinary chemical action, or to those variations in temperature which waters holding the ores in solution must undergo, as they rise upward from great depths in the earth. But there are other phenomena which do not admit of the same simple explanation. Thus, for example, in Derbyshire, veins containing ores of lead, zinc, and copper, but chiefly lead, traverse alternate beds of limestone and greenstone. The ore is plentiful where the walls of the rent consist of limestone, but is reduced to a mere string when they are formed of greenstone, or “toad-stone,” as it is called provincially. Not that the original fissure is narrower where the greenstone occurs, but because more of the space is there filled with vein-stones, and the waters at such points have not parted so freely with their metallic contents.

“Lodes in Cornwall,” says Mr. Robert W. Fox, “are very much influenced in their metallic riches by the nature of the rock which they traverse, and they often change in this respect very suddenly, in passing from one rock to another. Thus many lodes which yield abundance of ore in granite, are unproductive in clay-slate, or killas and _vice versa._

Supposed relative Age of the different Metals.—After duly reflecting on the facts above described, we cannot doubt that mineral veins, like eruptions of granite or trap, are referable to many distinct periods of the earth’s history, although it may be more difficult to determine the precise age of veins; because they have often remained open for ages, and because, as we have seen, the same fissure, after having been once filled, has frequently been re-opened or enlarged. But besides this diversity of age, it has been supposed by some geologists that certain metals have been produced exclusively in earlier, others in more modern times; that tin, for example, is of higher antiquity than copper, copper than lead or silver, and all of them more ancient than gold. I shall first point out that the facts once relied upon in support of some of these views are contradicted by later experience, and then consider how far any chronological order of arrangement can be recognised in the position of the precious and other metals in the earth’s crust.

In the first place, it is not true that veins in which tin abounds are the oldest lodes worked in Great Britain. The government survey of Ireland has demonstrated that in Wexford veins of copper and lead (the latter as usual being argentiferous) are much older than the tin of Cornwall. In each of the two countries a very similar series of geological changes has occurred at two distinct epochs—in Wexford, before the Devonian strata were deposited; in Cornwall, after the Carboniferous epoch. To begin with the Irish mining district: We have granite in Wexford traversed by granite veins, which veins also intrude themselves into the Silurian strata, the same Silurian rocks as well as the veins having been denuded before the Devonian beds were superimposed. Next we find, in the same county, that elvans, or straight dikes of porphyritic granite, have cut through the granite and the veins before mentioned, but have not penetrated the Devonian rocks. Subsequently to these elvans, veins of copper and lead were produced, being of a date certainly posterior to the Silurian, and anterior to the Devonian; for they do not enter the latter, and, what is still more decisive, streaks or layers of derivative copper have been found near Wexford in the Devonian, not far from points where mines of copper are worked in the Silurian strata.

Although the precise age of such copper lodes cannot be defined, we may safely affirm that they were either filled at the close of the Silurian or commencement of the Devonian period. Besides copper, lead, and silver, there is some gold in these ancient or primary metalliferous veins. A few fragments also of tin found in Wicklow in the drift are supposed to have been derived from veins of the same age.[9]

Next, if we turn to Cornwall, we find there also the monuments of a very analogous sequence of events. First, the granite was formed; then, about the same period, veins of fine-grained granite, often tortuous (see Fig. 614), penetrating both the outer crust of granite and the adjoining fossiliferous or primary rocks, including the coal-measures; thirdly, elvans, holding their course straight through granite, granitic veins, and fossiliferous slates; fourthly, veins of tin also containing copper, the first of those eight systems of fissures of different ages already alluded to, p. 607. Here, then, the tin lodes are newer than the elvans. It has, indeed, been stated by some Cornish miners that the elvans are in some instances posterior to the oldest tin-bearing lodes, but the observations of Sir H. de la Beche during the survey led him to an opposite conclusion, and he has shown how the cases referred to in corroboration can be otherwise interpreted.[10] We may, therefore, assert that the most ancient Cornish lodes are younger than the coal-measures of that part of England, and it follows that they are of a much later date than the Irish copper and lead of Wexford and some adjoining counties. How much later, it is not so easy to declare, although probably they are not newer than the beginning of the Permian period, as no tin lodes have been discovered in any red sandstone which overlies the coal in the south-west of England.

There are lead veins in Glamorganshire which enter the lias, and others near Frome, in Somersetshire, which have been traced into the Inferior Oolite. In Bohemia, the rich veins of silver of Joachimsthal cut through basalt containing olivine, which overlies tertiary lignite, in which are leaves of dicotyledonous trees. This silver, therefore, is decidedly a tertiary formation. In regard to the age of the gold of the Ural mountains, in Russia, which, like that of California, is obtained chiefly from auriferous alluvium, it occurs in veins of quartz in the schistose and granitic rocks of that chain, and is supposed by Sir R. Murchison, MM. Deverneuil and Keyserling to be newer than the syenitic granite of the Ural—perhaps of tertiary date. They observe that no gold has yet been found in the Permian conglomerates which lie at the base of the Ural Mountains, although large quantities of iron and copper detritus are mixed with the pebbles of those Permian strata. Hence it seems that the Uralian quartz veins, containing gold and platinum, were not formed, or certainly not exposed to aqueous denudation, during the Permian era.

In the auriferous alluvium of Russia, California, and Australia, the bones of extinct land-quadrupeds have been met with, those of the mammoth being common in the gravel at the foot of the Ural Mountains, while in Australia they consist of huge marsupials, some of them of the size of the rhinoceros and allied to the living wombat. They belong to the genera Diprotodon and Nototherium of Professor Owen. The gold of Northern Chili is associated in the mines of Los Hornos with copper pyrites, in veins traversing the cretaceo-oolitic formations, so-called because its fossils have the character partly of the cretaceous and partly of the oolitic fauna of Europe.[11] The gold found in the United States, in the mountainous parts of Virginia, North and South Carolina, and Georgia, occurs in metamorphic Silurian strata, as well as in auriferous gravel derived from the same.

Gold has now been detected in almost every kind of rock, in slate, quartzite, sandstone, limestone, granite, and serpentine, both in veins and in the rocks themselves at short distances from the veins. In Australia it has been worked successfully not only in alluvium, but in vein-stones in the native rock, generally consisting of Silurian shales and slates. It has been traced on that continent over more than nine degrees of latitude (between the parallels of 30° and 39° S.), and over twelve of longitude, and yielded in 1853 an annual supply equal, if not superior, to that of California; nor is there any apparent prospect of this supply diminishing, still less of the exhaustion of the gold-fields.

_Origin of Gold in California._—Mr. J. Arthur Phillips,[12] in his treatise “On the Gold Fields of California,” has shown that the ore in the gold workings is derived from drifts, or gravel clay, and sand, of two distinct geological ages, both comparatively modern, but belonging to different river-systems, the older of which is so ancient as to be capped by a thick sheet of lava divided by basaltic columns. The auriferous quartz of these drifts is derived from veins apparently due to hydrothermal agency, proceeding from granite and penetrating strata supposed to be of Jurassic and Triassic date. The fossil wood of the drift is sometimes beautifully silicified, and occasionally the trunks of trees are replaced by iron pyrites, but gold seems not to have been found as in the pyrites of similarly petrified trees in the drift of Australia.

The formation of recent metalliferous veins is now going on, according to Mr. Phillips, in various parts of the Pacific coast. Thus, for example, there are fissures at the foot of the eastern declivity of the Sierra Nevada in the state of that name, from which boiling water and steam escape, forming siliceous incrustations on the sides of the fissures. In one case, where the fissure is partially filled up with silica inclosing iron and copper pyrites, gold has also been found in the vein-stone.

It has been remarked by M. de Beaumont, that lead and some other metals are found in dikes of basalt and greenstone, as well as in mineral veins connected with trap-rock, whereas tin is met with in granite and in veins associated with the Plutonic series. If this rule hold true generally, the geological position of tin accessible to the miner will belong, for the most part, to rocks older than those bearing lead. The tin veins will be of higher relative antiquity for the same reason that the “underlying” igneous formations or granites which are visible to man are older, on the whole, than the overlying or trappean formations.

If different sets of fissures, originating simultaneously at different levels in the earth’s crust, and communicating, some of them with volcanic, others with heated Plutonic masses, be filled with different metals, it will follow that those formed farthest from the surface will usually require the longest time before they can be exposed superficially. In order to bring them into view, or within reach of the miner, a greater amount of upheaval and denudation must take place in proportion as they have lain deeper when first formed and filled. A considerable series of geological revolutions must intervene before any part of the fissure which has been for ages in the proximity of the Plutonic rock, so as to receive the gases discharged from it when it was cooling, can emerge into the atmosphere. But I need not enlarge on this subject, as the reader will remember what was said in the 30th, 32nd, and 35th chapters on the chronology of the volcanic and hypogene formations.

[1] Geol. Trans., vol. iv, p. 139; Trans. Royal Geol. Society, Cornwall, vol. ii, p. 90

[2] Conybeare and Phil. Geol., p. 401, and Farey’s Derbyshire, p. 243.

[3] Fournet, Études sur les Dépôts Métallifères.

[4] Carne, Trans. Geol. Soc., Cornwall, vol. iii, p. 238.

[5] Geol. Rep. on Cornwall, p. 340.

[6] Principles, chap. xxvii, 8th edit., p. 422.

[7] See Dr. Daubeny’s Volcanoes.

[8] Bulletin, iv, p. 1278.

[9] Sir H. De la Beche, MS. Notes on Irish Survey.

[10] Report on Geology of Cornwall, p. 310.

[11] Darwin’s South America, p. 209, etc.

[12] Proc. Royal Soc., 1868, p. 294.

INDEX.

——::——

_The Fossils, the names of which appear in Italics, are figured in the Text._

ABBEVILLE, flint tools of, 152 Aberdeenshire, granite of, 558 Abich, M., on trachytic rocks, 504 _Acer trilobatum,_ Miocene, 220, 221 _Acrodus nobilis,_ Lias, 359 Acrogens, term explained, 303 _Acrolepis Sedgwickii,_ Permian, 390 _Actæon acutus,_ Great Oolite, 345 _Actinocyclas,_ in Atlantic mud, 288 Actinolite, 499, 502 —— schist, 578 _Æchmodus Leachii,_ Lias, 358 _Adiantites Hibernica,_ Old Red, 441 Agassiz on fish of Sheppey, 267 —— on fish of the Brown-Coal, 540 —— on fish of Monte Bolca, 544 —— on Old Red fossil fish, 443, 447 —— on Silurian fish, 460 Age of metamorphic rocks, 597 —— of Plutonic rocks, 564 —— of strata, tests of, 123 —— of volcanic rocks, 520 Agglomerate described, 509 _Agnostus integer. A. Rex_, 488 Air-breathers of the Coal, 413 Aix-la-Chapelle, Cretaceous flora of, 302 Alabaster defined, 39 Alberti on Keuper, 376 Albite, 499, 500 Aldeby and Chillesford beds, 192 Alkali, present in the Palæozoic strata, 587 Alpine blocks on the Jura, 169 Alps, age of metamorphic rocks in, 599 ——, nummulitic limestone and flysch of, 77 Alum schists of Norway and Sweden, 489 Alluvial deposits, Recent and Post-pliocene, 151 Alluvium, term explained, 99 —— in Auvergne, 100 Alternations of marine and fresh-water strata, 72 Alum Bay beds, plants of the, 262 Amblyrhynchus cristatus, a living marine saurian, 362 America. _See_ United States, Canada, Nova Scotia. ——, North, Glacial formations of, 182 ——, South, gradual rise of land in, 72 ——, Silurian strata of, 478 American character of Lower Miocene flora, 238 —— forms in Swiss Miocene flora, 223 Amiens, flint tools of, 152 _Ammonites bifrons,_ Lias, 356 —— _Braikenridgii,_ Oolite, 351 —— _Bucklandi,_ Lias, 356 —— _Deshayesii,_ Neocomian, 311 —— _Humphresianus,_ Inferior Oolite, 351 —— _Jason,_ Oxford Clay, 340 —— _Noricus,_ Speeton, 312 —— _macrocephalus,_ Oolite, 352 —— _margaritatus,_ Lias, 357 —— _planorbis,_ Lias, 356 —— _rhotomagensis,_ Chalk marl, 298 Amphibole group of minerals, 499, 502 _Amphistegina Hauerina,_ Vienna basin, 225 _Amphitherium Broderipii,_ in Stonesfield, 348 —— _Prevostii,_ Stonesfield slate, 347 _Ampullaria glauca_, 56 _Amygdaloid_, 507 Analcime, 500 Anamesite, a variety of basalt, 504 _Ananchytes ovatus,_ White chalk, 293 ——, with crania attached, 49 _Ancillaria subulata,_ Eocene, 57 _Ancyloceras gigas_, 309 —— _spinigerum,_ Gault, 301 —— _Duvallei,_ Neocomian, 312 _Ancylus velletia (A. elegans)_, 55 Andalusite, 500 Andes, Plutonic rocks of the, 569 Andreasburg, metalliferous vein of, 611 Angelin, on Cambrian of Sweden, 489 Angiosperms, 303 —— of the Coal, 429 Anglesea, dike cutting through shale in, 514 _Anodonta Cordierii_, 54 —— _Jukesii,_ Upper Old Red, 441 —— _latimarginata_, 54 _Anoplotherium commune,_ Binstead, 254 —— _gracile,_ Paris basin, 271 Anorthite, 499, 501 _Annularia sphenophylloides,_ Coal, 425 _Antholithes,_ coal-measures, 429 Anthracite, conversion of coal into, 408 Anticlinal and synclinal curves, 74, 85 Antrim, Chalk altered by a dike in, 516 ——, Lower Miocene, volcanic rocks of, 539 Antwerp Crag, 204 Apateon pedestris, a carboniferous reptile, 406 Apatite, 500 Apennines, Northern, metamorphic rocks of, 599 Apes, fossil of the Upper Miocene, 215 _Apiocrinites rotundus,_ Bradford, 343 Appalachians, long lines of flexures in, 92, 93 ——, vast thickness of successive strata in, 110 _Aptychus,_ part of ammonite, 336 Aqueous rocks defined, 27, 35 _Araucaria sphærocarpa,_ Inferior Oolite, 348 Arbroath, section of Old Red at, 74 _Archæopteryx macrura,_ Solenhofen, 338 _Archegosaurus minor and A. medius,_ coal measures, 406, 407 Archiac, M. de, on nummulites, 277 ——, on chalk of France, 306 Arctic Miocene Flora, 239 Area of the Wealden, 319 Areas, permanence of continental, 117 Arenaceous rocks described, 35 _Arenicolites linearis,_ Arenig beds, 475 Arenig or Stiper-Stones group, 474 ——, volcanic formations of, 549 Argile plastique, 276 Argillaceous rocks described, 36 Argillite, Argillaceous schist, 579 Argyll, Duke of, on Isle of Mull leaf-beds, 247 Armagh, bone-beds in Mountain Limestone at, 437 Arran, amygdaloid filled with spar near, 518 ——, erect trees in volcanic ash of, 546 ——, Greenstone dike in, 514 Arthur’s seat, trap rocks of, 545 _Arvicola,_ tooth of, 165 _Asaphus caudatus,_ Silurian, 467 —— _tyrannus, A. Buchii_, 474 Ascension, lamination of volcanic rocks in, 595 Ash, Mr., on fossils of Tremadoc beds, 483 Ashby-de-la-Zouch, fault in coal field of, 91 _Aspidura loricata,_ Muschelkalk, 379 _Astarte borealis_ (=_A. arctica=A. compressa_), 176 —— _Omalii,_ Crag, 199 _Asterophyllites foliosus,_ Coal, 425 _Astrangia lineata (Anthophyllum lineatum)_, 229 _Astræa basaltiforme,_ Carboniferous, 432 _Astropecten crispatus,_ London clay, 266 Atherfield clay, 309 Atlantic mud, composition of, 287 _Atrypa reticularis,_ Aymestry, 462 _Aturia ziczac (Nautilus ziczac)_, 266 Augite, 499, 502 _Auricula,_ recent, 55 Austen, Mr. Godwin, on marine deposit of Selsea Bill, 182 ——, on boulders in chalk, 292 Australian cave breccias, 158 Australia, auriferous gravel of, 617 Auvergne, alluvium in, 100 ——, chain of extinct volcanoes in, 495 ——, granite veins in, 610 ——, Lower Miocene of, 233 ——, Miocene volcanic rocks of, 540 ——, Post-pliocene volcanic eruptions in, 527 ——, springs from spent volcanoes in, 604 Aveline Mr., on Tarannon shales, 468 _Avicula contorta,_ Rhætic beds, 366 —— _cygnipes,_ Lias, 355 —— _inæquivalvis,_ Lias, 355 —— _socialis,_ Muschelkalk, 379 _Aviculopecten papyraceus,_ coal measures, 405 —— _sublobatus,_ mountain limestone, 434 Aymestry Limestone, 461 Azoic period, supposed, 603 Azores, Miocene lavas with shells, 539

_BACILLARIA paradoxa_, 51 _Baculites anceps,_ Lower Chalk, 298 —— _Fauiasii,_ chalk, 286 Baffin’s Bay, formation of drift in, 171, 173 Bagshot sands, 258, 259, 262 Baiæ, Bay of, subterranean igneous action in, 569 Bakewell, Mr., on cleavage in Swiss Alps, 590 Bala and Caradoc beds, 470 _Balistidæ,_ defensive spine of, 261 Bangor, or Longmynd group, 485 _Banksia,_ seed and fruit of, Lower Miocene, 238 Barmouth sandstones, 486 Barnes, Mr. J., on insects in American coal, 416 Barnstaple, Upper Devonian of, 450 Barrande, M. Joachim, his “Primordial Zone,” 471, 482, 487 ——, on metamorphosis of trilobites, 471 Barrett, Mr., on bird in Blackdown beds, 299 Barton series sands and clays, 258 —— shells, percentage of, common to London clay, 258 Basalt, columnar, 511 ——, composition of, 504 Basaltic rocks, poor in silica, 504 ——, specific gravity of minerals in, 504 _Basilosaurus,_ Eocene, United States, 280 Basset, term explained, 83 Basterot, M. de, on Bordeaux tertiary strata, 141 Bath Oolite, 342 Batrachian reptiles in coal, 406 Bay of Fundy, denudation in coalfield in, 418 Bean, Mr., on Yorkshire Oolite, 350 Bear Island carboniferous flora, 441 Beaumont, M. E. de, on island in Cretaceous sea, 305 ——, on mineral veins, 613 ——, on Jurassic plutonic rocks, 571 ——, on formation of granite, 553 Beckles, Mr. S. H., on footprints in Hastings sands, 315, 330 —— on Mammalia of Purbeck, 326 _Belemnitella mucronata,_ Chalk, 283 _Belemnites hastatus,_ Oxford clay, 340 —— _Puzosianus,_ Oxford clay, 341 Belgium, Lower Miocene of, 241 _Bellerophon costatus,_ Mountain Limestone, 436 _Belosepia sepioidea,_ Sheppey, 266 Belt, Mr., on subdivision of Lingula Flags, 484 Bembridge beds, Yarmouth, 252 Berger, Dr., on rocks altered by dikes, 515 Berlin, Miocene strata near, 242 Bernese Alps, gneiss in the, 599 Berthier on isomorphism, 502 Bertrich-Baden, columnar basalt of, 512 Beyrich on term Oligocene for Lower Miocene, 244 Billings, Mr., on trilobites, 471 Binney, Mr., on Sigillariæ in volcanic ash, 546 ——, on Stigmaria, the root of Sigillaria, 426 Biotite, 499, 501 Bird in argile plastique, 276 Bischoff, Professor, on Nile and Rhine mud, 154 ——, on conversion of coal into anthracite, 403 ——, on hydrothermal action, 586 Blackdown beds, 301 Blacklead of Borrowdale, 65 Bog-iron-ore, 52 Bohemia, Cambrian rocks of, 487 ——, silver veins in, 616 Bolderberg, in Belgium, Upper Miocene of, 224 Bone-bed of fish remains, Armagh, 437 —— of Upper Ludlow, 450 —— of the Trias, 367 Boom, Lower Miocene of, 241 Bordeaux, Upper Miocene of, 214 Borrowdale, blacklead of, 65 Bosquet, M. on chalk fossils, 283 ——, on Maestricht beds, 283 Botanical nomenclature, 303 Boucher de Perthes on Abbeville alluvium, 152 Boulder-clay, whether formed by icebergs or land-ice, 166-73, 178 Boulder-clay of Canada, 182 —— fauna of, 176, 189 Boulders and pebbles in chalk, 292 Bournemouth beds (Lower Bagshot), 262 Bovey Tracey, lignites and clays of, 246 Bowerbank, Mr., on fossil fruits of London Clay, 265 ——, on fossil fruits of Sheppey, 265 Bowman, Mr., on uniting of distinct coal-seams, 401 Brachiopoda, preponderance of, in older rocks, 470 ——, mode of recognising shells of, 471 Bracklesham beds and Bagshot Sands, 259 Bradford encrinites, 342 Breccias of Lower Permian, 391 Brick-earth or fluviatile loam, 153 Bridlington drift, 189 Bristol, dolomitic conglomerate of, 373 Bristow, Mr., on volcanic minerals, 500 Brixham cave near Torquay, 158 Brocchi on Italian tertiary strata, 141 —— on subapennine strata, 208 Brockenhurst, corals and shells of, 257 Brodie, Rev. P. B., on Lias insects, 363 Brodie, Mr. W. R., on Purbeck mammalia, 326 Brongniart, M. Adolphe, on botanical nomenclature, 303 ——, on Lias plants, 364 ——, on flora of the Bunter, 380 ——, on flora of the coal, 420 ——, on fruit of Lepidodendron, 424 ——, M. Alex., on Tertiary series, 141 _Bronteus flabellifer_, Devonian, 453 Brora, oolitic coal formation of, 350 Brown, Mr. Richard, on Stigmaria, 426 ——, on carboniferous rain-prints, 416 Brown, Robert, on Eocene protaceous fruit, 264 Brown, Reverend T., on marine shells in Scotch drift, 177 Brown-coal of Germany, 540 Bryce, Mr., on Scotch till, 176 Bryozoa of Mountain Limestone, 433 —— and polyzoa, terms explained, 197 Buch, von. _See_ Von Buch. Buckland, Dr., on Kirkdale cave, 158 ——, on violent death of saurians, 362 ——, on spines of fish, 359 ——, on Eocene oysters, 268 ——, on pot-stones in chalk, 291 Buddle, Mr., on creeps in coal-mines, 78 _Bulimus ellipticus_, Bembridge, 253 —— _lubricus_, Loess, 56 Bullock, Capt., R.N., on Atlantic mud, 287 Bunbury, Sir C., on leaf-bed of Madeira, 532 ——, on ferns of the Maryland coal, 421 Bunter of Germany, 380 —— or Lower Trias of England, 372 _Buprestis? Elytron of_, Stonesfield, 346 Burmeister on trilobites, 471

CAINOZOIC, term defined, 123 Caithness, fish beds of, 443 _Calamite_, root of, 425 _Calamites Sucowii_, coal, and restored stem, 424 _Calamophyllia radiata_, Bath Oolite, 342 Calcaire de la Beauce, age of the, 230 —— grossier, fossils of the, 274 —— siliceux of France, 273 Calcareous matter poured out by springs, 604 —— rocks described, 36 —— nodules in Lias, 63 _Calcarina rarispina_, Eocene, 275 _Calceola sandalina_, Devonian, 453 ——, schiefer of Germany, 453 California, aurifrous gravel of, 617 ——, gold in petrified wood of age of alluvium, 601 _Calymene Blumenbachii_, Silurian, 466 Cambrian Group, classification of the, 481 Cambrian, Upper, 482 ——, Lower, 484 ——, of Sweden and Norway, 489 ——, strata of Bohemia, 487 ——, of North America, 489 ——, volcanic rocks, 549 _Campophyllum flexuosum_, 431 Canada, Cambrian of, 489 ——, Devonian of, 455 ——, trap-rocks of, 549 Canadian drift, 182 Canary, Grand, shelly tuffs of, 538 Cantal, Lower Miocene of the, 231 Cape Breton, rain-prints in coal-measures of, 416 Cape Wrath, granite veins in gneiss at, 560 Caradoc and Bala beds, 470 Carbonate of lime in rocks, how tested, 37 Carboniferous Group, subdivisions of the, 394 —— flora, 420-30 —— limestone, thickness of, 396 ——, marine fauna of the, 432 —— Period, trap-rocks of, 545 —— plutonic rocks, 572 —— reptiles, 406 —— insects, 405 _Carcharodon angustidens_, Bracklesham, 262 Cardiganshire, section of slaty cleavage in, 589 _Cardiocarpon Ottonis_, Permian, 393 _Cardita (Venericardia) planicosta_, 260 —— _sulcata_, Barton, 259 _Cardium dissimile_, Portland Stone, 336 —— _rhæticum_, Rhætic Beds, 366 —— _striatulum_, Kimmeridge clay, 336 Carne, Mr. N., on Cornish lodes, 607 Carpenter, Dr., on Atlantic mud, 288 ——, on Eozoon Canadense, 491 Carrara, marble of, 599 Carruthers, Mr., on Eocene proteaceous fruit, 265 ——, on cycads of the Purbeck, 332 ——, on leaves of calamite, 425 ——, on spores of carboniferous Lycopodiaceæ, 422 ——, on structure of sigillaria, 426 ——, on trees in volcanic ash, 547 Cashmere, recent formations in, 146 Cassian, St., Triassic strata of, 376 Castrogiovanni, curved strata near, 86 Catania, laterite formed in, 510 ——, Tertiary beds in, 206 _Catillus Lamarckii_, White Chalk, 295 Caucasus, absence of lakes in the, 187 _Caulopteris primæva_, Coal, 421 Cave-breccias of Australia, 158 Cavern deposits with human and animal remains, 156 Caves of Kirkdale and Brixham, 157 Celts described, 152 Cementing of strata, 61 _Cephalaspis Lyelli_, Old Red, 446 _Ceratites nodosus_, Muschelkalk, 379 _Cerithium concavum_, Headon, 256 —— _elegans_, Hempstead beds, 245 —— (_Terebra_) Portlandicum, 335 —— _plicatum_, Hempstead beds, 245 —— _melanoides_, 268 _Cervus alces_, tooth of, 164 _Cestracion Phillippi_, Recent, 297 Chabasite, 500 Chalk, composition, extent, and origin of, 286 —— of Faxoe, 286 —— flints, origin of, 290 —— fossils of the White, 293-6 ——, iceborne boulders in the, 292 —— of North and South Europe, 305 ——, Lower White, without flints, 298 —— marl, fossils of the, 298 —— Period, popular error concerning, 288 Chalk-pit with pot-stones, view of, 291 _Chama squamosa_, Barton, 258 Champoleon, junction of granite with Jurassic strata near, 571 _Chara elastica, C. medicaginula_, 58 —— _tuberculata_, Bembridge, 253 Charpentier, M., on Alpine glaciers, 170 ——, on depression of Alps in Glacial Period, 185 Chatham coal-field, 383 _Cheirotherium_, footprints of, 372 Chemical deposits in veins, 612 —— and mechanical deposits, 60 Chiapa, fall of volcanic dust at, 523 Chichester, erratics near, 181 Chili, copper pyrites with gold in, 616 ——, walls cracked by earthquake in, 87 Chillesford and Aldeby beds, 192 _Chimæra monstrosa_, Lias, 359 Chlorite-schist, 579 Chloritic series, or Upper Greensand, 298 Christiania, Euritic porphyry at, 562 ——, granite veins in Silurian strata of, 572 ——, quartz vein in gneiss at, 561 Chronological groups of formations, 129 Chronology, test of, in rocks, 121 Cinder-bed of the Purbeck, 325 _Cinnamomum polymorphum_, Miocene, 219 —— _Rossmässleri_, Miocene, 239 Claiborne beds, Eocene fossils of, 279 Clarke County, United States, Zeuglodon of, 279 Classification of Tertiary formations, 137, 143 ——, value of shells in, 142 _Clausilia bidens_, Loess, 56 Clay defined, 36 —— iron-stone defined, 404 ——, plastic, 267 —— slate, 579 ——, Weald, 313 Cleavage explained, 502 ——, crystalline theory of, 591 ——, mechanical theory of, 592 —— of metamorphic rocks, 588 _Cleidotheca operculata_, 483 Clermont, metalliferous gneiss near, 586 Climate of the Crags, 200 —— of the Coal, 430 —— of the Miocene in the Arctic regions, 240 —— of the Post-pliocene period, 161 Clinkstone, 506 Clinton group, fossils of the, 479 Clyde, buried canoes in estuary of, 146 ——, arctic marine shells in drifts of, 176 _Clymenia linearis_, Devonian, 451 Clymenien-Kalk of Germany, 450 Coal, conversion into anthracite of, 403 —— a land and swamp formation, 397 ——, cause of the purity of, 402 ——, conversion of lignite into, 403 ——, erect trees in, 411 ——, structure of the, 412 ——, vegetation of the, 420 ——, air-breathers in the, 405, 413 Coal Period, climate of the, 430 —— field of Virginia, 382 —— measures of Nova Scotia, 408 —— measures, thickness of, in Wales, 397 —— pipes, danger of, 390 ——, rainprints in, 416 —— seams, uniting of, 400 Coalbrook-Dale, faults in, 88 _Cochliodus contortus_, 437 Cockfield Fell rocks, altered by dikes, 516 _Coelacanthus granulatus,_ Permian, 390 Coleoptera of Œningen beds, 223 _Collyrites ringens,_ Inferior Oolite, 351 Columnar structure of volcanic rocks, 510 —— basalt in the Vicentin, 511 Compact feldspar, 501 Concretionary structure, 63 Cone of Tartaret, 527, 542 —— of Côme, 28 Cones and craters described, 495 ——, absence of, in England, 30 Conformable stratification, 39 Conglomerate or pudding-stone, 36 ——, Dolomitic, of Bristol, 373 Coniferæ of the coal-measures, 427 Connecticut Valley, New Red Sandstone of, 381 _Conocephalus striatus_, 488 _Conocoryphe striata_, 488 Conrad, Mr., on age of American cretaceous rocks, 307 Consolidation of strata, 61 Continents and oceans, permanence of, 117 Contorted strata, in drift, 178 _Conularia ornata,_ Devonian, 453 _Conulus priscus,_ Coal, 415 _Conus deperditus,_ Bracklesham, 262 Conybeare and Phillips on ninety-fathom dike, 90 Conybeare, Mr., on reptiles of the Lias, 360 Copper lode near Redruth, 607 Coprolite bed of Chloritic Series, 299 —— beds of Red and Coralline crags, 197, 198 _Coprolites of fish from the chalk_, 298 Coral Rag, fossils of the, 339 Coralline of White Crag, 197 Corals of the Devonian, 451 —— of the Mountain Limestone, 433 ——, _Neozoic type of_, 431 ——, _Palæozoic type of_, 431 _Corbicella (Cyrena) fluminalis_, 54 _Corbula pisum,_ Hempstead beds, 245 Corinth, corrosion of rocks by gases near, 586 Cornbrash or Forest Marble, 341 Cornwall, granite veins in, 561, 582 ——, lodes in, 615 ——, mass of granite in, 552 ——, vertical sections of veins in mine, 607 Cosequina volcano, burying of organic remains by, 523 Crag, term defined, 192 —— of Antwerp, 204 ——, fauna of, its relation to that of present seas, 201 ——, Norwich, 193 ——, Coralline or White, 197 ——, Red, 194 ——, tables of marine testacea in, 202 —— deposits, climate of, 200 _Crania_ attached to a sea-urchin, 49 —— _Parisiensis,_ White Chalk, 294 _Crassatella sulcata,_ Barton, 259 Craters and cones described, 495 ——, Theory of Elevation, 496 Craven fault, 90 Creeps in coal-mines, 78 Cretaceous rocks of United States, 307 —— Period, error as to continuity of, 288 ——, flora of the Upper, 302 —— volcanic rocks, 544 —— plutonic rocks, 570 —— Period, distinct mineral character of rocks in, 292 —— rocks, classification of, 282 —— strata, connection between Upper and Lower, 301 Crinoidea of Mountain Limestone, 433 Croatia, Lower Miocene beds of, 242 Croll, Mr., on amount of subaërial denudation, 114 Cromer forest-bed, 191 Crop out, term explained, 83 Crossopterygidæ, or fringe-finned fish, 443 Crowfoot, Mr., on shells of Aldeby beds, 192 Crust of the earth defined, 26 Crustaceans of Old Red Sandstone, 446 _Cryptodon angulatum,_ London Clay, 266 Crystalline Limestone, 579 —— rocks defined, 32 —— schists, much alkali in the, 587 —— theory of cleavage, 591 Cup and Star corals, 431 Curved strata, 73-76 Cutch, salt-layers in the Runn of, 375 Cuvier, M., on fauna of the Paris basin, 271 ——, on Mammalia of Paris gypsum, 231 ——, on Tertiary series, 141 _Cyathocrinus caryocrinoides_, 433 —— _planus_, 433 _Cyathophyllum cæspitosum_, 451 Cyclopean isles, beds of tuff and clay in, 529 ——, contorted strata in, 530 _Cyclopteris Hibernica,_ Old Red, 441 _Cyclostigma (Lepidodendron),_ Old Red, 441 _Cyclostoma elegans,_ Loess, 56 _Cylindrites acutus,_ Great Oolite, 345 Cypress swamps of the Mississippi, 402 Cyprides in the Weald Clay, 315 _Cypridina serrato-striata_, 451 Cypris in fresh-water deposits, 57 —— _gibbosa, C. tuberculata, C. leguminella_, 324 —— _striato-punctata, C. fasciculata, C. granulata_, 325 —— _Purbeckensis, Cypris punctata_, 331 —— _spinigera,_ Weald Clay, 315 _Cyrena (Corbicella) fluminalis_, 54 —— _cuneiformis,_ Woolwich Clays, 268 —— _obovata_, 54 —— _semistriata,_ Hempstead beds, 245 Cystideæ of Silurian rocks, 466 _Cythere inflata,_ coal-measures, 405

DADOXYLON, fragment of coniferous wood, 428 Dana, on volcanic minerals, 500 Danish kitchen-middens, 146 _Dapedius monilifer_, Lias, 358 Darbishire on shells of Moel Tryfaen, 180 Dartmoor, post-carboniferous granite of, 572 —— intrusive granite at, 572 Darwin, Mr., on foliation and lamination, 595 ——, on mammalia of South America, 160 ——, on marine saurian, 362 ——, on rise of part of South America, 72 ——, on sinking of coral reefs, 72 ——, on plutonic rocks of the Andes, 569 ——, on relationship of extinct to living types, 160 Dates of discovery of fossil vertebrata, 464 Daubeny, Dr., on decomposition of trachytic rocks, 586 Daubrée, on formation of zeolites, 521 ——, on alkaline waters of Plombières, 584 Davidson, Mr., on Spiriferina, 355 Davis, Mr. E., on fossils of Lingula Flags, 484 Dawkins, Mr. Boyd, on Hyæna spelæa, 158 ——, on mammalia of Cromer Forest-bed, 191 ——, on Triassic mammifer, 369 Dawson, Dr., on Devonian flora and insects, 456, 457 ——, on Eozoon Canadense, 491 ——, on Nova Scotia coal-measures, 409 ——, on Nova Scotia coal-plants, 410, 412 ——, on Pupa vetusta, 415 ——, on reptiles and shells in Nova Scotia coal, 413 ——, on structure of calamite, 425 ——, on structure of sigillaria, 426 Deane, Dr., on footprints in Trias, 382 Debey, Dr., on flora and fauna of Aix, 302-04 Dechen, M. von, on organic remains of the brown coal, 540 ——, on Cornish granite veins, 560 De la Beche, Sir H., on granite of Dartmoor, 582 ——, on Carrara marble, 599 ——, on mineral veins, 616 ——, on Redruth copper-mine, 610 ——, on saurians of the Lias, 362 ——, on trap-rocks of New Red, 545 ——, on Welsh coal-measures, 397 Delesse, on action of water in metamorphism, 585 Deltas, strata accumulated in, 28 Dendrerpeton in Coal, 413 Denudation defined, 96 ——, subaërial, 97 ——, littoral, 102 ——, submarine, 105 ——, average annual amount of subaërial, 113 —— of carboniferous strata, 396 —— counteracting upheaval, 106-15, 108-15 —— a means of exposing crystalline rocks, 563 ——, trap-dikes cut off by, 518 —— and volcanic force antagonistic powers, 115 Deposition, rate of, shown by fossils, 47 Derbyshire, veins in Mountain Limestone, 608 Derivative shells of the Red Crag, 195-203 Desnoyers, M., on age of Faluns, 142 ——, on Eocene fossil footprints, 272 Desor, M., on Celtic coins in lake-dwellings, 149 Devonian Period, Upper, 450 Middle, 450 Lower, 453 —— fossils of the Eifel, 534 —— of Russia, 454 —— of United States and Canada, 455 —— insects of Canada, 457 —— strata, classification of, 439-50 Devonshire, cleavage of slate rocks in, 593 Diabase, 505 Diagonal, or cross-stratification, 42 Diagram of fossiliferous rocks, 137 —— of plutonic and sedimentary formations, 567 Diallage, 500, 502 _Diastopora diluviana_, Bath Oolite, 343 Diatomaceæ forming tripoli, 51 _Diceras Lonsdalii_, Neocomian, 310 _Didelphys Azaræ_, Recent, 347 _Didymograpsus geminus_, 476 —— _Murchisonii_, 473 Dike cutting through shale, Anglesea, 515 —— cutting through chalk, Antrim, 515, 516 _Dikelocephalus Minnesotensis_, 490 Dikes defined, 30 —— of Monte Somma, 526 —— in Palagonia, ground-plan of, 532 ——, volcanic or trap, 513-7 Diluvium, origin of term, 167 Dinornis Palapteryx, of New Zealand, 160 _Dinotherium giganteum_, 212 Diorite, 505 Dip and strike, terms explained, 80 _Diplograpsus folium_, Llandeilo Flags, 474 —— _pristis_, Llandeilo beds, 473 Dirt-bed of the Purbeck, 331 Dogger-bank described, 105 Dolerite, a variety of basalt, 504 Dolomite defined, 38 Dolomitic conglomerate of Bristol, 373 Downs, escarpments of North and South, 104 Downton Sandstone, 459 Dowson, Mr., on shells of Aldeby beds, 192 Drew, Mr., on Hastings Sands, 316 Drift of Ireland, 190 —— of Norfolk cliffs, 190 —— of Scandinavia, 174 —— of Bridlington, 189 —— carried by icebergs, 172 —— shells in Canada, 183 ——, contorted strata in, 178 ——, marine shells in Scotch, 175 Dudley Limestone, 465 Dufrenoy, M., on granite of Pyrenees, 582 Dumont, Professor, on Belgian Lower Eocene, 282 Duncan, Dr., on Neozoic corals passing down to Devonian, 432 Dundry Hill, near Bristol, section of, 130 Dunker, Dr., on wealden of Germany, 319 Dura Den, yellow sandstone of, 440

EARTH’S crust defined, 26 Echinoderms of Suffolk Crag, 200 _Echinosphæronites balticus_, 472 Egerton, Sir P., on fish of Headon series, 256 ——, on fish of the Permian, 389 ——, on fish of Penarth beds, 366 Ehrenberg, Professor, on term Bryozoum, 197 ——, on Silurian foraminifera, 478 ——, on infusoria, 51 Eifel Limestone, 453 ——, Lake-craters of, 534 —— Miocene, volcanic rocks of, 539 —— Pliocene, volcanoes of the, 534 ——, trass of the, 535 _Elephas antiquus_, molar of, 163 —— _meridionalis_, molar of, 163 —— _primigenius_, molar of, 162 Elevation craters, theory of, 496 Elvans, term explained, 572 —— of Ireland and Cornwall, 615 _Elytron of Buprestis?_ Stonesfield, 346 Emmons, Professor, on jaws of Triassic quadruped, 383 ——, on Dromatherium, 383 Encrinites of Bradford, 342 _Encrinus liliiformis_, Muschelkalk, 379 Endogens, term explained, 303 Engihoul cave, human and animal remains in, 157 England and Wales, glaciation of, 180 Enstatite, 501 Eocene areas of Europe, map of, 250 —— foraminifera, 274 —— formations of France, 270-6 —— of England, 252 —— period, volcanic rocks of, 543 ——, plutonic rocks of the, 568 ——, metamorphic rocks of the, 598 —— of France, footprints in, 272 —— and Miocene, line between the, 230, 250 ——, term defined, 143 —— of the United States, 278 _Eozoon Canadense_, oldest known fossil, 492 Epidote, 500 Eppelsheim, Dinotherium of, 225 Equisetaceæ of the Coal, 424 _Equisetites columnaris_, Keuper, 376 _Equus caballus_, tooth of, 164 Erratic blocks, nature of, 167 —— of Greenland, 171 —— near Chichester, 181 —— in the Red Crag, 201 Erratics, Alpine, 169 Escarpments explained, 104 _Eschara disticha_, White Chalk, 296 _Escharina oceani_, White Chalk, 296 _Estheria minuta_, Trias, 370 —— _ovata_, Richmond, Virginia, 383 Ethridge, Mr., on Atlantic mud, 288 ——, on Devonian series, in Devon, 450 ——, on Devonian fauna, 451, 454 ——, on mollusca of Bracklesham, 260 ——, on St. Cassian fossils, 377 Etna, built up since Newer Pliocene, 204 ——, Pliocene lavas of, 529 Ettingshausen on Sheppey Eocene fruit, 265 _Eunomia radiata_, Bath Oolite, 342 _Eunotia bidens_, Atlantic mud, 288 _Euomphalus pentangulatus_, 435 Eurite, 557, 578 Euritic porphyry of Norway, 562 Evans, Mr., on Archæopteryx, 337 Exogens, 297 _Exogyra virgula_, Kimmeridge Clay, 336 _Extracrinus (Pentacrinus) Briareus_, Lias, 357

FALCONER, Dr., on Miocene fauna of Siwalik Hills, 226 ——, on Brixham Cave flint knives, 157 ——, on Purbeck mammalia, 326 Faluns of Loire, recent shells in, 214 —— of Touraine, 211 Farnham, phosphate of lime near, 299 _Fascicularia aurantium_, Coralline crag, 199 Faults in coal-measures of Coalbrook Dale, 88 —— described, 87-92 —— often the result of repeated movements, 90 Fauna of the crag, its relation to that of our present seas, 201 —— of the Mountain Limestone, 430 —— of the Paris basin, 271 _Favosites cervicornis_, Devonian, 451 —— _Gothlandica_, Silurian, 465 Favre, M. E., on glaciers and moraines of the Caucasus, 187 Faxoe, chalk of, 285 Feldspar-porphyry, 557 Feldspar, varieties of, 499, 500 Feldstone, 557 _Felis tigris_, tooth of, 166 _Fenestella retiformis_, Magnesian Limestone, 388 Ferns of the coal, 421 Fife, trap-dike in, 543 Fish, fossil of the Carboniferous, 436 ——, Eocene of Monte Bolca, 544 ——, oldest known fossil, 463 ——, number of living, 445 ——, fresh-water and marine, 58 —— of the Upper Ludlow, 459 —— of the Old Red Sandstone, 443-5 —— of the Permian marl slate, 389 —— of the brown coal, 540 —— of the Lias, 358 Fisherton, Greenland lemming in drift of, 161 Fissures, filled with metallic matter, 606 Fitton, Dr., on the Neocomian strata, 314 Fleming, Dr., on Parka decipiens, 448 ——, on trap-dike in Fife, 546 Flints in the Chalk, 290 Flisk dike of Fife, 546 Flora of the Carboniferous, 420 ——, Devonian, compared to Carboniferous, 457 —— of the Subapennines, 208 ——, Lower Miocene of Switzerland, 235 ——, Miocene of the Arctic Regions, 239 ——, Older Pliocene of Italy, 208 —— of the Permian, 392 —— of the Upper Cretaceous, 302 ——, Upper Miocene of Switzerland, 215-22 —— of the Wealden, 320 Fluvio-marine or Norwich Crag, 193 Flysch of the Alps, 278 ——, plutonic rocks invading, 568 Folding and denudation of Nova Scotia Carboniferous rocks, 417 Folds of parallel strata, arrangement and direction of, 93 Foliation of crystalline rocks, 595 ——, irregularities in, 596 Folkestone and Hythe beds, 308 Fontainebleau, Gres de, 230 Footprints in Potsdam sandstone, 490 —— _of reptiles in Coal-measures_, 408 ——, _fossil in New red_, 381 —— in Paris gypsum, 272 Foraminifera, Eocene, 275 —— of Mountain Limestone, 437 —— of the Chalk, 287 Forbes, Mr. David, on glass cavities in quartz, 555 ——, on planes of foliation, 595 ——, on specific gravity of quartz, 500 ——, on volcanic minerals, 498 Forbes, Professor E., on fossils of Bembridge beds, 252 ——, on Hempstead beds, 244 ——, on shells of the crag, 200 ——, on sphæronites, 472 ——, on subdivisions of the Purbeck, 333 ——, on testacea of the Faluns, 212 ——, on thickness of Upper Neocomian, 309 Forest-bed at Cromer, 191 —— marble or cornbrash, 341 ——, submerged, 103, 104 ——, fossil in Coal, 400 ——, fossil of Isle of Portland, 332 Forfarshire, Cephalaspis beds of, 446 ——, contorted strata in, 178 Formation, term defined, 27 Fossil, term defined, 29 —— trees erect in coal, 410 —— Fish of Old Red Sandstone, 442 Fossiliferous groups, table of succession of, 131 Fossils, arrangement of, in strata, 47 ——, destruction of, in older formations, 139 ——, fresh-water and marine, 52 —— obliterated by metamorphic action, 603 ——, recent, and Post-pliocene, 154-65 —— of the drift, 176, 180, 192 —— of the Crags, 193-203 ——, Upper Miocene, 214-29 ——, Lower Miocene of Switzerland, 236 —— of the Hempstead Beds, 244 ——, Eocene, 253 —— of the Barton Clay, 259 —— of the White Chalk, 293 —— of the Neocomian, 309 —— of the Oolite, 324 —— of the Stonesfield Slate, 347 —— of the Lias, 354 —— of the Trias, 370 —— of the Magnesian Limestone, 387 —— of the Coal, 405 —— plants of the Coal, 421 —— of the Mountain Limestone, 430 ——, Devonian, 449 ——, Silurian, 460 ——, Cambrian, 484 —— Laurentian, 492 Fournet, M. on metalliferous gneiss, 586 ——, on veins in granite, 610 Fox, Rev. D., on Isle of Wight Eocene fossils, 254 Fox, Mr. R., on lodes in Cornwall, 614 Fractures of strata, and faults, 87 Fragments, included, a test of age of plutonic rocks, 565 ——, included, a test of age of strata, 129 —— a test of age in volcanic rocks, 524 France, Eocene formations of, 270-6 ——, Lower Miocene of, 231 ——, Upper Miocene of, 211 Freshfield, Mr., on absence of lakes in the Caucasus, 187 Fresh-water strata, how distinguished from marine, 53-9 —— formation of Auvergne, 233 Fucoid sandstones of Sweden, 489 _Fulgur canaliculatus_, Maryland, 228 Fuller’s earth, fossils of the, 348 Fundy, Bay of, fossil trees exposed in cliffs at, 412 _Fusilina cylindrica_, 438 Fusion of quartz, 500 _Fusus contrarius (Trophon antiquum)_, 196 —— _quadricostatus_, Maryland, 228

GABBRO, 505 _Gaillonella ferruginea_, and _G. distans,_ 52 Galapagos Islands, living marine saurian in, 362 _Galeocerdo latidens_, Bracklesham, 262 _Galerites albogalerus_, White Chalk, 294 Galestes in Middle Purbeck, 328 Ganoids, the type of Old Red Sandstone fish, 443 —— of the Wealden, 316 —— of the Trias, 383 Gaps in the sequence of fossil remains, 138 Garnet, 500 Gases, corrosion of rocks by, 586 Gaudin on Lower Miocene of Switzerland, 236 —— on Pliocene flora of Italy, 209 —— on Proteaceæ in Bournemouth Eocene, 263 Gault, thickness and fossils of, 300 Geikie, Mr. A., on Ayrshire Permian trap-rocks, 545 ——, on subaërial denudation, 115 ——, on ice erosion of lake-basins, 187 ——, on Isle of Mull volcanic rocks, 539 ——, on Pentland Old Red volcanic rocks, 548 ——, on Silurian metamorphic rocks, 602 ——, on syenite of Skye, 568 Geinitz, M., on Permian flora, 393 Gemunder Maar, volcanic rocks of, 534 Geneva, Lower Miocene of, 236 Geology defined, 25 Gergovia, tuffs and associated lacustrine strata of, 542 Germany, Lower Miocene of, 242 ——, Triassic fauna of, 375 Gers, Upper Miocene of, 215 _Gervillia anceps_, Neocomian, 310 —— _socialis_, Muschelkalk, 379 Giant’s Causeway basalt, age of, 248 ——, laterite of the, 509 ——, columnar basalt of, 510 Girgenti, Newer Pliocene of, 207 Glacial drift, distribution and nature of, 166 —— epoch in the Post-pliocene, 166 —— formations of Pliocene age, 189-92 Glaciation of Russia and Scandinavia, 174 —— of Scotland, 175 —— of Wales and England, 180 —— of North America, 182 Glaciers, transporting and abrading power of, 168 Glasgow, marine strata near, 146 Glauconie grossiere, 275 Glen Tilt, junction of granite and schist at, 559 Globiform pitchstone, 512 _Globigerina bulloides_, 288 Globular structure of volcanic rocks, 510 _Glyptostrobus, Europæus,_ Œningen, 223 Gneiss, granite veins traversing, 560 —— defined and figured, 577 ——, fundamental, of Scotland, 493 Gold mines of Australia and Chili, 616 —— veins of Russia, 616 —— of California, of age of alluvium, 617 Goldenberg, Professor, on Saarbrück coal insects, 406 Goldfuss, Professor, on reptiles in coal, 406 _Goniatites crenistria_, 436 —— _Listeri,_ coal-measures, 405 Göppert, on American forms in Swiss Miocene flora, 223 —— on petrification, 68 —— on plants of coal-measures, 398 _Gorgonia infundibuliformis,_ Permian, 388 Graham’s Island, forming ashy conglomerate, 549 Grampians, Old Red conglomerates of, 73 ——, trap-rocks of the, 547 ——, former glaciers in the, 175 Grand Canary, Upper Miocene, shelly tuffs of, 558 Granite, composition of, 552 ——, graphic and columnar, 553, 554 ——, how far connected with trap-rocks, 558 ——, hydrothermal action in formation of, 555 —— metamorphosing fossiliferous strata, 581 ——, porphyritic, 556 ——, oldest, 574 ——, protrusion of solid, 574 ——, passage of, into trap, 558 ——, schorly, 557 —— veins, 559 —— veins in talcose gneiss, 560 Granton, angiosperm found in coal at, 429 Graptolites of Llandeilo flags, 474 _Graptolites Murchisonii._ Llandeilo flags, 473 _Graptolithus priodon,_ Silurian, 467 Gray’s, Essex, pachyderms found at, 161 Great (or Bath) Oolite, 342 Greece, Upper Miocene formations of, 226 Greenland, continental ice of, 170 ——, gradual sinking of, 72 Greenstone, 505 Gres de Beauchamp, Paris basin, 273 Gres de Fontainebleau, age of the, 230 Griffiths, Sir R., on yellow sandstone of Ireland, 441 Grit defined, 36 Groups, older, rise highest above the sea, 139 —— why the newest to be studied first, 140 _Gryllacris lithanthraca,_ coal, 405 _Gryphæa_ coated with _serpulæ_, 48 —— _columba,_ Chloritic Sand, 300 —— _convexa,_ Chalk, 295 —— _incurva (G. arcuata)_, 54, 354 —— _virgula,_ Kimmeridge clay, 336 Gryphite Limestone, 354 Guadaloupe, glass cavities in quartz of, 555 Gulf-Stream, probable abrading power of, 105 Gümbel, M., on Rhætic beds, 366 Gunn, Mrs., on pot-stones in the chalk, 291 Gutbier, Colonel, on Permian flora, 393 Gymnogens, term explained, 303 Gypseous marls of Auvergne, 233 Gypsum and gypseous marl defined, 38, 39 _Gyrolepis tenuistriatus,_ Rhætic beds, 367

HAIME, Mr., on palæozoic corals, 431 _Hakea silicina_ and _Hakea saligna,_ Œningen, 222 Hall, Captain Basil, on Cyclopean Isles, 530 Hall, Sir James, on curved strata, 75 Hall, Mr. J., on Appalachian palæozoic rocks, 110 Hallstadt and St. Cassian beds, 376 _Halysites catenularis,_ Silurian, 465 Hamilton, Sir W., on eruption of Vesuvius, 1779, 526 _Hamites spiniger,_ Gault, 301 Hancock, Mr., on Protosaurus in Permian, 390 Harkness, Professor, on Silurian metamorphic rocks, 602 Harlech grits, fossils of the, 486 Harris, Major, on the Salt Lakes, 374 _Harpactor maculipes,_ Œningen, 224 Harpe, M. de la, on Bournemouth Eocene flora, 263 Hartung, Mr., cited, 496 Hartz mountains, mineral veins of, 608 ——, Bunter Sandstein of, 380 Hastings Sands, subdivisions of the, 316 Hautes Alpes, granite of the, 571 Hauy on isomorphism, 502 Headon series, fossils of the, 255 Heat, powerful in consolidating rocks, 65 ——, rocks upraised and folded by, 92 Hébert, M., on age of Sables de Bracheux, 330 ——, comparison of Sables Moyens and Barton shells, 258 ——, on pisolitic limestone, 285 Hebrides, dikes in the, 514 Heer, Professor, on American genera in Swiss Miocene, 239 ——, on age of Madeira leaf-bed, 532 ——, on Arctic Miocene flora, 239 ——, on Bear Island flora, 441 ——, on Bovey Tracey Miocene flora, 247 ——, on fossil plants of Switzerland, 215, 219, 221, 224, 236 ——, on Lower Miocene plants of Mull, 248 ——, on Monte Bolca Eocene plants, 263, 543 ——, on Proteas of Lower Miocene, 237 ——, on plants of Hempstead beds, 246 ——, on plants of coal-field, Virginia, 383 ——, on Swiss Miocene insects, 223 ——, on supposed Proteaceæ of Œningen beds, 221 ——, on Superga fossil plants, 244 Heidelberg, varieties of granite near, 560 _Heliolites porosa_, Devonian, 451 _Helix hispida (plebeia)_, 155 —— _labyrinthica,_ Headon, 255 —— _occlusa,_ Bembridge, 253 —— _Turonensis,_ faluns, 56 _Hemicidaris Purbeckensis,_ Purbeck, 324 _Hemipneustes radiatus,_ Chalk, 284 _Hemitelites Brownii,_ Inferior Oolite, 350 Hempstead beds, subdivisions of the, 244 Henry, on absorption of carbonic acid gas in water, 585 Henslow, Professor, on dike in Anglesea, 515 ——, on Red Crag coprolite bed, 197 Herschel, Sir J., on slaty cleavage, 590 Hertfordshire pudding-stone, 62 _Heterocercal tail of fish_, 389 Hicks, Dr., on fossils of Arenig beds, 476 ——, on fossils of Harlech grits, 486 ——, on Menevian beds, 485 Himalaya, shells 18,000 feet high in, 29 ——, Upper Miocene of, 226 _Hippopodium ponderosum,_ Lias, 355 _Hippopotamus, tooth of_, 164 Hippurite Limestone, 304 _Hippurites organisans,_ Chalk, 306 _Histioderma hibernica_, 486 Hitchcock, Professor, on Trias footprints, 381 _Holoptychius nobilissimus,_ scale of, and restoration, 442 _Homalonotus Delphinocephalus_, 467 —— _armatus,_ Devonian, 454 Homfray, Mr., on fossils of Tremadoc beds, 483 _Homocercal tail of fish_, 389 Hooghly River, analysis of water, 69 Hooker, Dr., on coniferæ, 429, 430 ——, on structure of sigillaria, 426 ——, on sporangia of Silurian plant, 460 Horizontality of strata, 40 Horizontal strata, upheaval of, 71 Hornblende, 499, 502 Hornblende-schist, 578 Hörnes, Dr., on fossil mollusca of Vienna basin, 225 Horstead, pot-stones at, 291 Hour-glass illustrating the destruction and renovation of land, 119 Howse, Mr., on Protosaurus in Permian, 390 Hubbard, Professor, on granite of White Mountains, 565 Hudson River Group, fossils of the, 479 Hughes, Mr. T. McKenny, cited, 450 ——, on slaty cleavage, 589 ——, on protrusion of solid granite, 575 Hull, Mr. E., on breccias in Permian, 391 ——, on carboniferous of Lancashire, 395 ——, on carboniferous rocks of north of England, 111 ——, on faults in Lancashire coal-field, 91 ——, on anticlinals and synclinals, Lancashire, 85 ——, on thickness of the Upper Trias, 369 ——, on thickness of Permian, 386 ——, on three lines of flexure since the coal in Lancashire, 94 Human remains of Recent Period, 157 —— in cavern deposits, 156 Humboldt, on mineral character of rocks, 602 Humphrey and Abbot on Mississippi denudation, 114 Hungary, trachyte of, 558 Hunt, Sterry, on action of water in metamorphism, 585 Huronian series, thickness of the, 490 Huxley, Professor, on Atlantic chalk-mud, 287 ——, on affinity between reptiles and birds, 338 ——, on batrachians of the coal, 407 ——, on fish of Old Red Sandstone, 443-5 ——, on Pteraspis, 463 Hyæna den of Kirkdale cave, 157 _Hyæna spelæa,_ tooth of, 165 _Hybodus plicatilis,_ Rhætic beds, 367 —— _reticulatus,_ Lias, 359 Hydrothermal action producing metamorphism, 584 —— in formation of granite, 555 —— forming granite veins, 573 _Hymenocaris vermicauda_, 484 _Hyperodapedon Gordoni,_ Trias, 370 Hypersthene, 499, 502 —— rock, 505 —— rocks of Skye, 491 Hypogene rocks, uniformity of mineral character in, 602 —— rocks, term defined, 26 _Hypsiprymnus Gaimardi,_ molar of recent, 327 Hythe, Neocomian beds of, 308

ICE, erosion of lake-basins considered, 184, 188 ——, abrading power of, 168 ——, continental, of Greenland, 170 Icebergs, drift carried by, 172 —— stranded in Baffin’s Bay, 173 Ice-borne erratics at Chichester, 181 Iceland, glass cavities in quartz of, 555 ——, flow of lava in, 523 _Ichthyosaurus communis,_ Lias, 361 Idocrase, 500 Ichthyodorulite of the Lias, 359 _Iguanodon Mantelli,_ Weald Clay, 315 Ilfracombe Group of Devon, 449 Inclined strata, 73 India, Miocene formations of, 226 India, Upper Miocene of, 226 Inferior Oolite, thickness and fossils of, 349 Infusoria in tripoli, 51 Inland sea-cliffs, 103 _Inoceramus Lamarckii,_ White Chalk, 295 Insect in American coal, 416 —— beds of the Lias, 363 _Insect wing of neuropterous_, 363 Insects, Devonian, of Canada, 457 —— in European coal, 405 ——, Miocene, of Croatia, 243 ——, Upper Miocene, at Œningen, 223 Intrusion, a test of age of Plutonic rocks, 565 ——, a test of age of volcanic rocks, 521 Inundation mud of rivers, 153 Ireland, glacial drift of, 190 ——, yellow sandstone of, 441 Iron pyrites, 500 —— weapons of Swiss lake-dwellings, 148 _Isastræa oblonga,_ Portland Sand, 335 Isle of Bourbon, lava current of the, 566 —— Wight, Hempstead beds, 244 —— Wight, Eocene beds, 255 —— Mull, Miocene leaf-bed of, 247 —— Mull, volcanic rocks, 248 Isomorphism, theory of, 502 Italy, Lower Miocene of, 244 ——, Older Pliocene volcanoes of, 523 ——, Pliocene of, 207 ——, Older Pliocene flora of, 208 ——, Upper Miocene strata of, 226

JAMIESON, Mr. T. F., on Scotch glacial drift, 175 Jaws of mammalia in Purbeck, 327 Jeffreys, Mr. Gwyn, on Atlantic mud, 288 Jointed structure of metamorphic rocks, 589 Jones, Dr. Rupert, on Eozoon Canadense, 491 Jorullo, lava stream of, 566 Judd, Mr., on Speeton clay, 311 Jukes, Mr., on Tarannon shales, 468 Jura, erratic blocks on the, 169 ——, structure of the, 82

KANGAROO, jaws of, 159 Käsegrotte, Bertrich Baden, Basaltic pillars of, 512 Kaup, Professor, on footprints of the Trias, 373 Keilhau, Professor, on granite veins, 562 ——, on planes of foliation, 595 ——, on Silurian granite of Norway, 573 ——, on protrusion of granite, 581 Keller, Dr. F., on lake-dwellings, 148 Kelloway Rock, percentage of Oxford clay fossils in, 341 Kentish Rag, 308 Keuper, of Germany, 375 —— or Upper Trias of England, 369 Kilkenny, fossil plants of, 441 Killas, altered by granite in Cornwall, 582 Kiltorkan, yellow sandstone of, with Anodonta, 441 Kimmeridge Clay, 335 King, Dr., on reptile footprints in coal, 407 King, Mr., on Permian fossils, 388 Kirkdale cave, hyæna’s den of, 157 Kitchen-middens of Denmark, 146 Kleyn Spawen beds, 242 Könen, Baron von, on Brockenhurst shells, 257 Koninck, M. de, on Mountain Limestone fish, 436 ——, on shells of Mayence basin, 242 _Koninckia Leonhardi,_ Hallstadt, 377

LABRADOR rock, 505 —— series, 490 Labradorite, 499, 501 _Labyrinthodon Jægeri, section of tooth_, 371 ——, _tooth of_, 370 Labyrinthodonts of Coal, 407 Lake-craters of the Eifel, 534 Lake districts, southern limits of the, 184 Lake-dwellings, scarcity of human remains in, 149 —— of Switzerland, 148 Lakes, deposits in, 27 ——, connection of, with glacial action, 184-8 Lamarck on bivalve mollusca, 54 Lamination of clay slate, 594 _Lamna elegans,_ Bracklesham, 262 Lancashire, vast thickness of rocks without corresponding altitude in, 111 Land, balance of dry, how preserved, 116, 118 —— has been raised, not the sea lowered, 70 ——, mean height of, above the sea, 115 ——, rise of, in Sweden, 72 ——, rise and fall of, affecting denudation, 101 Land-ice, action of, in Greenland, 171 Land’s End, columnar granite at, 553 ——, porphyritic granite at, 556 La Roche, recent deposits in estuary of, 40 Lartet, M., on mammalia of Faluns, 214 ——, on Gastornis Parisiensis, 276 ——, on reindeer period, 150 _Lastræa stiriaca,_ Monod, 239 Lateral compression causing curved strata, 75 Laterite of Giant’s Causeway, 509 Laurentian gneiss of Scotland, 493 —— Group, Upper and Lower, 491 —— metamorphic rocks, 601 —— volcanic rocks, 549 Lava, 507 —— consolidating on slopes, 496 —— currents of Auvergne, 541 —— streams, effect of, 30 —— of La Coupe d’Ayzac, 511 —— of Jorullo, 566 Lead veins, age of, 616 Leaf-bed of Madeira in basalt and scoriæ, 532 ——, Isle of Mull Miocene, 248 _Leda amygdaloides,_ London Clay, 266 —— _Deshayesiana (Nucula Deshayesiana)_, 241 —— _lanceolata (L. oblonga),_ Scotch drift, 176 —— _truncata,_ Scotch drift, 177 Lee, Mr. J.E., on Pteraspis of Lower Ludlow, 463 Leidy, Dr., on fossil quadrupeds of Nebraska, 249 _Leperditia inflata,_ coal-measures, 405 _Lepidodendron,_ Griffithsii, 441 —— _corrugatum,_ carboniferous., 417 —— _Sternbergii,_ coal-measures, 423 Lepidolite, 499, 501 _Lepidostrobus ornatus,_ Coal, 424 _Lepidotus gigas,_ Lias, 358 —— _Mantelli,_ Wealden, 317 _Leptæna depressa,_ Wenlock, 466 —— _Moorei,_ Lias, 355 Level of surface altered by change of subterranean heat, 119 Lewis, hornblendic gneiss of, 601 Lias, fishes of the, 358 ——, fossils of the, 354 —— and Oolite, origin of the, 364 ——, reptiles of the, 360 ——, insects of the, 363 ——, plants of the, 364 ——, plutonic rocks of the, 571 ——, subdivisions of the, 353 ——, volcanic rocks of the, 544 Liebig, on conversion of coal into anthracite, 403 ——, on origin of stalactite, 156 Liége, limestone caverns at, 156 Lightbody, Mr., on Lower Ludlow shales, 461 Lignite, conversion of into coal, 403 _Lima giganteum_, 354 —— _Hoperi,_ Chalk, 300 —— _spinosa,_ White Chalk, 294 Limagne d’Auvergne, Lower Miocene mammalia of the, 234 Limburg beds, 242 Lime, scarcity of, in metamorphic rocks, 604 —— in solution, source of, 69 Limestone, block of striated, 168 ——, brecciated, 387 —— of chemical and organic origin, 61 ——, compact, 501 ——, Hippurite, 304 ——, magnesian, 387 ——, metamorphic or crystalline, 579 ——, Mountain, and its fossils, 430-8 ——, striated, 168 _Limnæa longiscata_, 55 Lingula beds, volcanic tuffs of the, 549 _Lingula Credneri_, Permian, 388 Lingula Flags, fossils of the, 484 _Lingula Dumortieri,_ Crag, 200 —— _Lewisii,_ Ludlow, 462 _Lingulella Davisii_, 484 Lipari Isles, tufas in, 586 _Liquidambar europæum_, 209 _Lithrostrotion basaltiforme,_ Carboniferous, 432 Lits coquilliers, 275 Littoral denudation defined, 102 _Lituites giganteus,_ Ludlow, 463 Llanberis slates, 486 Llandeilo Flags, fossils of the, 473-5 Llandeilo formation, thickness of the, 475 ——, Lower, 475 Llandovery Group, classification of the, 468 —— Rocks, thickness of the Lower, 469 Loam defined, 38, 153 Lodes, shells and pebbles in, 608 —— _See_ Mineral Veins. Loess of fluviatile loam described, 153 ——, fossil shells of the, 154 Logan, Sir W., on Eozoon Canadense, 490 ——, on Gaspe sandstones, 455 ——, on Huronian and Laurentian, 490 ——, on stigmaria in under-clays, 398 ——, on thickness of Nova Scotia coal, 409 ——, on thickness of Laurentian in Canada, 113 Loire, faluns of the, 211 London Clay, fossils of the, 264, 266 Longevity, relative, of mammalia and testacea, 162 Longmynd Group, fauna of the, 486 Lonsdale, Mr., on corals of America, 229 ——, on Devonian fossils, 449 ——, on Stonesfield slate, 345 ——, on United States Miocene corals, 229 _Lonsdaleia floriformis,_ Carboniferous, 432 Lowe, Reverend R. T., on Mogador shells, 537 Lubbock, Sir J., on the two stone-periods, 147 _Lucina serrata,_ Bracklesham, 262 Ludlow formation, Upper, 459; Lower, 461 ——, bone-bed of the Upper, 459 Lulworth Cove, dirt-bed of, 333 Lycett, Mr., on fossils of the Great Oolite, 344 Lycopodiaceæ of Coal, 422 _Lycopodium densum,_ living species, 423 Lym-fiord, mingled fresh-water and marine strata of, 59 _Lymnea caudata,_ Headon, 256 —— _longiscata,_ Bembridge, 253 Lynton Group of Devon, 454

MACLAREN, Mr., on Pentland Hills, volcanic rocks, 548 Macclesfield, marine shells 1,200 feet high at, 181 MacClintock, Sir L., on Atlantic mud, 287 MacCulloch, Dr., on Aberdeenshire granite, 558 ——, on basaltic columns in Skye, 510 ——, on formation of hornblende-schist, 582 ——, on trap, 519 MacMullen, Mr. J., on Eozoon Canadense, 491 _Macropus atlas,_ lower jaw of, 158 —— _major_ (living), lower jaw of, 159 Madeira, beds of laterite in, 509 ——, dike in valley in, 513 ——, Pliocene leaf-bed and shells in lavas of, 532 ——, Miocene volcanic rocks of, 536 ——, wind, removing scoriæ in, 97 Maestricht beds and their fossils, 283 Maffiotte, Don Pedro, cited, 538 _Magas pumila,_ White Chalk, 294 Magnesian Limestone defined, 38 —— and marl-slate, 387 Magnetite, 500 Maidstone, Upper Cretaceous fossils of, 297 Malacolite, 502 Malaise, Professor, on Engihoul cave, 157 Mammalia, anterior to Paris gypsum, table of, 329 ——, extinct, coeval with man, 152, 157 ——, fossil, of Middle Purbeck, 325 ——, fossil, in Pliocene in Val d’Arno, 208 ——, fossil, in the Crag, 193, 197 ——, fossil, of Vienna basin, 225 —— of the Limagne d’Auvergne, 234 —— of Siwalik Hills, 227 —— of the Stonesfield slate, 345 ——, _teeth of Post-pliocene_, 165 Mammalia and testacea, comparative longevity of, 162 Mammoth, rude carving of in Perigord cave, 150 —— in Scotch till, 175 —— _See_ Elephas primigenius. Man, antiquity of, 152 Manfredi on amount of subaërial denudation, 114 Mantell, Dr., on iguanodon of Wealden, 313 ——, on Oxford Clay belemnites, 340 ——, on Wealden fossils, 316 _Mantellia nidiformis,_ Purbeck, 331 Map of Chalk formation in France, 305 —— of Eocene tertiary basins, 250 —— of Hallstadt and St. Cassian beds, 376 Marble defined, 37 —— of Carrara, metamorphic, 599 Marcou, M., on age of Wealden beds, 319 Margaric acid, 591 Marine fauna of the Carboniferous, 432 —— beds underlying the London Clay, 269 —— and brackish-water strata in coal, 404 —— strata, how distinguished from fresh-water, 53-59 Marl from Lake Superior, 63 —— and marl-slate defined, 38 ——, red, green, and white, of Auvergne, 233 —— slate of Middle Permian, 387 Marsupials, extinct, of Australia, 159 _Marsupites Milleri,_ White Chalk, 294 Massachusetts, plumbago of, 583 _Mastodon arvernensis,_ molar of, Norwich crag, 193 —— _giganteus,_ in United States after the drift, 183 Mayence basin tertiaries, 242 May-Hill Sandstone, 468 Mechanical and chemical deposits, 60 —— theory of cleavage, 592 Mediterranean, one zoological province, 127 _Megalodon cucullatus,_ Devonian, 452 _Melania inquinata (Cerithium melanoides)_, 55, 268 _Melania turritissima,_ Bembridge, 253 _Melanopsis buccinoidea_, 55 Melaphyre, a variety of basalt, 504 Menevian beds and their fossils, 484 Mesozoic, term explained, 123 —— and Cainozoic periods, gap between the, 282 —— and Palæozoic rocks, limits of the, 385 Metals, relative age of different, 614 Metamorphic limestone, 579 —— strata, origin of, 579 —— theory, objections to, considered, 587 —— rocks defined, 32 Metamorphic rocks, 576 ——, cleavage of, 588 ——, scarcity of lime in, 604 ——, ages of, 597 ——, order of succession of, 602 ——, uniformity of mineral character in, 602 Metamorphism, hydrothermal action producing, 584 Metamorphosis of trilobites, 471, 487 Meteorites, minerals in, 501 Mexico, Gulf of, terrestrial remains washed into, 128 Meyer, Mr. Karl, on fossil shells of Madeira, 537 ——, M. H. von, on reptiles in coal, 407 ——, on Wealden of Germany, 319 Miascite, 558 Mica and its varieties, 499, 501 ——, how deposited, 40 —— schist or micaceous schist, 578 Micaceous sandstone, origin of, 36 _Micraster cor-anguinum_, 294 _Microconchus carbonarius,_ coal-measures, 405 _Microlestes antiquus,_ Upper Trias, 368 Migrations of quadrupeds, 161 Miliolite limestone, 274 Miller, Hugh, on Old Red Sandstone fish, 443 ——, on salt lakes, 375 Milne Edwards, Mr., on Palæozoic corals, 432 Minchinhampton, Great Oolite of, 344 Mineral composition a test of age of volcanic rocks, 523 —— a test of age of plutonic rocks, 565 —— a test of age of strata, 124 —— character of hypogene rocks, 602 —— springs of Auvergne, 604 Mineral veins, 605 —— formed in fissures, 606 ——, successive formation of, 609 ——, swelling and contraction of, 611 ——, relative age of, 614 ——, pebbles in, 608 Mineralisation of organic remains, 65 Minerals in meteorites, 501 ——, table of the most abundant in hypogene rocks, 499 Miocene of Bordeaux and south of France, 214 —— and Eocene, line between the, 230, 251 ——, Lower, of England, 244 ——, Lower, of Germany and Croatia, 242 ——, Lower, of Central France, 231 ——, Lower, of Italy, 244 ——, Lower, of Nebraska, United States, 248 ——, term defined, 143 ——, Upper, of the Bolderberg, 224 ——, Upper, of France, 211 ——, Upper, of Italy, 226 ——, Upper, of Greece, 226 ——, Upper, of India, 226 ——, Upper, of Vienna basin, 224 Mississippi, sediment of, used as a test of denudation by rivers, 114 —— valley, deposition and denudation in the, 102 Mitchell, Mr., on Aralia fruit in Alum Bay, Eocene, 263 Mitchell, Sir T., on Wellington caves, 158 Mitchell, Rev. Hugh, on Pteraspis, 446 _Mitra Scabra,_ Barton clay, 259 Mitscherlich, on Isomorphism, 502 _Modiola acuminata,_ Permian, 387 Moel Tryfaen, shells found at, 181 Mohs on isomorphism, 502 Molasse, Lower, of Switzerland, 235 ——, Middle, or Marine, of Switzerland, 223 ——, Upper, fresh-water, of Switzerland, 217 ——, term explained, 217 Mollusca. _See_ Shells. ——, longevity of species of, 162 —— of Hallstadt beds, 377 ——, value of, in classification, 142 —— of the Carboniferous, 435 Monitor of Thuringia, 463 Monoclinic feldspars, 501 Monod, flora of the Lower Molasse at, 236 Mons, unconformable strata near, 95 Montblanc, talcose granite of, 568 —— Dor, Auvergne, extinct volcanoes of, 232 ——, age of volcano of, 541 Monte Bolca, fossil fish of, 543 —— Calvo, section of cross stratification, 44 —— Mario, age of volcanic deposits of, 533 —— Nuovo, formed 1538, 525 Montmartre, gypseous series of, 270 Monts Dome, Auvergne, extinct volcanoes, 495 Moore, Mr. C., on Rhætic beds, 366 ——, on Upper Trias quadrupeds, 369 Moraines described, 169 Morea, cretaceous volcanic rocks of, 544 Mortillet, M. de, on ice-erosion of lake-basins, 184 Morton, Dr., on age of American cretaceous rocks, 307 _Mosasaurus Camperi,_ Chalk, 284 Mountain Limestone, fossils of the, 433-8 Mull, Isle of, leaf-bed, 247 Münster, Count, on fossils of Solenhofen, 337 Murchison, Sir R., on brackish-water strata in coal, 404 ——, on Devonian series, 439, 449, 454 ——, on Devonian ichthyolites, 453 ——, on Eocene igneous rocks, 278 ——, on Llandovery beds, 468 ——, on Laurentian gneiss of Scotland, 492 ——, on metamorphic rocks of North Highlands, 601 ——, on Monte Bolca fish-beds, 543 ——, on name Permian, 385 ——, on Old Red Sandstone, 449 ——, on Palæozoic strata, Queenaig, 112, 113 ——, on protrusion of solid granite, 574 ——, on Silurian, 458, 459, 461, 467, 470, 473, 475 ——, on Tertiary volcanic rocks of Italy, 533 ——, on thickness of chalk in Russia, 287 ——, on thickness of the Trias, 369 ——, on the Upper “Old Red”, 468 _Murchisonia gracilis_, 479 _Murex vaginatus_, 204 Muschelkalk, fossils of the, 378 Muscovite, or common mica, 499, 501 Musk-ox, fossil, in Thames valley, 161 _Myliobates Edwardsi,_ Bracklesham, 261 _Mytilus septifer,_ Permian, 387

NAPLES, Post-pliocene volcanic rocks of, 525 ——, escape of carbonic acid near, 604 _Natica clausa,_ Scotch drift, 176 —— _helicoides,_ Chillesford beds, 192 Natrolite, 500 _Nautilus centralis,_ London Clay, 266 —— _Danicus,_ Faxoe Chalk, 286 —— _plicatus,_ Hythe beds, 309 —— _truncatus,_ Lias, 356 —— _ziczac (Aturia ziczac)_, 266 Nebraska, Miocene strata of, 248 Necker, M., on “underlying” igneous rocks, 562 ——, on dikes in Vesuvius, 526 Neocomian, Upper, 308 ——, Middle, 312 ——, Lower, 312 ——, use of the term, 282 Neolithic era, 147 Neozoic type of corals, 431 _Nerinæa Goodhallii,_ Coral Rag, 339 Nerinæan limestone, 340 _Nerita conoidea (N. Schmidelliana)_, 275 —— _costulata,_ Great Oolite, 345 —— _granulosa_, 55 _Neritina concava,_ Headon, 255 —— _globulus_, 55 Neufchâtel, coins and iron tools in lake of, 149 Newberry, Dr., on flora of American cretaceous rocks, 307 Newcastle coal-field, faults in, 90 Newfoundland bank described, 106 New Jersey, mastodon in, 183 New Madrid, “Sunk Country” in, 402 New Red sandstone of Connecticut Valley, 381 ——, trappean rocks of the, 545 New York, Devonian strata of, 456 ——, Cambrian strata of, 490 ——, Silurian strata of, 478 ——, Laurentian strata of, 491 Niagara Limestone, fossils of the, 479 Nidau, iron tools in lake of, 148 Nile, homogeneous mud of the, 154 Ninety-fathom dike in coal, 90 _Nipadites ellipticus,_ Sheppey, 264 Nodules in strata, how formed, 63 _Noeggerathia cuneifolia,_ Permian, 393 Nomenclature of rocks, 140 —— of volcanic minerals, 499 Norfolk cliffs, drift of, 190 North America. _See_ America. Norway, Cambrian of, 489 ——, foliation of crystalline schists in, 595 ——, granite veins in gneiss of, 573 ——, granite altering fossiliferous strata in, 581 Norwich, or Fluvio-marine crag, 193 Nova Scotia coal-measures, 409 —— coal, reptiles and shells in, 414 ——, folding and denudation of beds in, 417 _Nucula Cobboldiæ,_ Crag, 194 _Nummulites lævigata,_ Bracklesham, 260 —— _Puschi,_ Pyrenees, 278 —— _variolaria,_ Bracklesham, 259 Nummulitic formations, 277

_OBOLUS APOLLINIS,_ in Russian grit, 478 Obsidian, 505 Oceanic areas, permanence of, 117 Œningen, Upper Miocene beds of, 215 Oeynhausen, M. von, on Cornish granite veins, 560 _Ogygia Buchii_, 474 _Oldhamia radiata: O. antiqua_, 487 Old Red Sandstone, Upper, 440 ——, Middle, with fish, 443 ——, Lower, 446 ——, trap of the, 547 ——, classification of, 439 _Olenus micrurus_, 484 Oligocene, term for Lower Miocene, 230, 244 Oligoclase, 499, 500 _Oliva Dufresnii,_ Bolderberg, Belgium, 224 Olivine, 499 _Omphyma turbinatum,_ Silurian, 466 _Onchus tenuistriatus,_ Silurian, 460 Oolite, classification and physical geography of the, 321 ——, defined, 37 ——, Inferior, fossils of the, 349, 350 —— and Lias, origin of the, 364 —— and Chalk, Palæontological break between, 338 Oolitic strata, palæontological relations of, 351 —— volcanic rocks, 545 _Ophioderma tenuibrachiata,_ Lias, 357 Oppel on zones of Lias, 353 Orbigny, Alcide de, on foraminifera of Vienna basin, 225 ——, on orbitoidal limestone, 279 ——, on Pisolitic limestone, 285 ——, on Sénonian, 302 _Oreodaphne Heerii,_ Italian Pliocene, 209 Organic remains, mineralisation of, 65 ——, tests of age of strata, 125 ——, tests of age of volcanic rocks, 522 ——, geological provinces of, 127 Oriskany Sandstone, 478 _Orthis elegantula,_ Ludlow, 46 —— _grandis,_ Caradoc beds, 470 —— _tricenaria,_ Bala beds, 470 —— _vespertilio,_ Bala beds, 470 _Orthoceras duplex,_ 474 —— _Ludense,_ Silurian, 463 —— _laterale_, 436 —— _ventricosum,_ Silurian, 462 Orthoclase, 499, 500 Orthoclastic feldspars, 501 Osborne or St. Helen’s series, Eocene, 255 _Osteolepis,_ Old Red Sandstone, 444 _Ostraceon,_ spine of, Bracklesham, 261 _Ostrea acuminata,_ Fuller’s earth, 349 —— _carinata,_ Chalk marl, 300 —— _columba,_ Chloritic sand, 300 —— _gregarea,_ Coral Rag, 339 —— _deltoidea,_ Kimmeridge clay, 336 —— _distorta,_ Middle Purbeck, 324 —— _expansa,_ Portland sand, 336 —— _Marshii,_ Oolite, 351 —— _vesicularis,_ Chalk, 295 _Otodus obliquus,_ Bracklesham, 262 Outcrop of strata, 83 Overlapping strata, 95 Owen, Professor on Archæopteryx, 337 ——, on Eocene Zeuglodon, 279 ——, on footprints in Trias, 382 ——, on fauna of Sheppey, 265, 267 ——, on Gastornis Parisiensis, 276 ——, on Labyrinthodon, 370 ——, on mammalia of Stonesfield, 347 ——, on Purbeck mammalia, 326, 328 ——, on reptiles of coal, 407, 414 ——, on zoological provinces of extinct animals, 160 _Ox, tooth of_ (recent), 165 Oxford Clay, thickness and fossils of, 340

PAGHAM, erratic block at, 182 _Palæaster asperimus,_ 472 _Palæchinus gigas,_ Mountain Limestone, 43 _Palæocoma tenuibrachiata,_ Lias, 357 _Palæoniscus,_ Permian fish, 389 —— _comptus, P. elegans, P. glaphyrus_, 390 _Palæotherium magnum_, 254 _Palæophis typhoeus,_ Bracklesham, 261 Palæozoic or Paleozoic, term defined, 123 —— Plutonic rocks, 572 —— rocks, 458 —— type of corals, 431 Palagonia, dikes of lava in, 531 Paleolithic era, 147, 149 ——, alluvial deposits of, 150 Palm in Swiss Miocene, 237 Palma, volcanic crater of, 497 _Paludina lenta,_ Hempstead beds, 55 —— _orbicularis,_ Bembridge, 253 _Paradoxides Bohemicus_, 488 —— _Davidis,_ Lower Cambrian, 485 Parallelism of folded strata for long distances, 93 Paris basin, Tertiary group first studied in, 141 ——, Tertiaries of the, 270 _Parka decipiens,_ “Old Red,” 448 Parkfield Colliery, ground-plan of, 400 Patagonia, strata of, rich in soda, 587 _Patella rugosa,_ Great Oolite, 345 Paterson, Dr., on angiosperm of the Coal, 429 Peach, Mr. C, cited, 601 ——, Pteraspis, found by, 443 Pearlstone, 505 Pebbles in mineral veins, 608 —— in chalk, 292 _Pecopteris elliptica,_ Coal, 421 _Pecten Beaveri,_ White Chalk, 294 —— _cinctus,_ Neocomian, 312 —— _islandicus,_ Scotch Drift, 176 —— _jacobæus,_ in tertiary of Sicily, 206 —— _quinque-costatus_, 300 —— _Valoniensis,_ Rhætic beds, 366 Pegmatite, 553 Penarth beds, 366 Pengelly, Mr., on Bovey Tracey lignite, 246 ——, on flint-knives of Brixham Cave, 157 _Pentacrinus Briareus,_ Lias, 357 _Pentamerus Knightii,_ Aymestry, 461 —— _oblongus,_ and _P. lirata_, 469 Pentland Hills, volcanic rocks of the, 548 Perigord cave, carving of mammoth in, 150 Permanence of continents and oceans, 117 Permian Flora, 392 —— of Germany, 393 —— strata, thickness of, in north of England, 386 ——, Upper and Middle, 386, 387 ——, Lower, 390 _Perna Mulleti,_ Neocomian, 310 Petherwyn, Devonian fossils of, 450 Petrifaction, process of, 67 _Petrophiloides Richardsoni,_ Sheppey, 25 _Pahcops caudatus,_ Silurian, 467 —— _latifrons,_ Devonian, 450 _Phascolotherium Bucklandi_, 348 _Phasianella Heddingtonensis,_ and cast, 66 Phillippi, on tertiary shells of Sicily, 205 Phillips, Professor, on fossils distorted by cleavage, 592 ——, on ninety fathom dike, 90 ——, on Wenlock limestone and shale, 465, 467 ——, on Yoredale series, 395 Phillips, Mr. J. Arthur, on origin of gold of California, 617 _Phlebopteris contigua,_ Inferior Oolite, 350 Phlogopite, 499, 501 _Pholadomya fidicula,_ Inferior Oolite, 350 Phonolite, 506 _Phorus extensus,_ London Clay, 266 _Phragmoceras ventricosum,_ Silurian, 463 _Physa Bristovii,_ Middle Purbeck, 325 —— _columnaris_, 55 —— _hypnorum_, 55 Piedmont, absence of lakes in, 186 Pile dwellings of Switzerland, 148 Pilton, group of, Devon, 449 _Pinnularia in Atlantic mud_, 288 Pinus sylvestris in peat, 147 Pisolitic limestone of France, 285 Pitchstone, 505 _Placodus gigas,_ Muschelkalk, 380 Placoids, rare in Old Red Sandstone, 443 _Plagiaulax Becklesii, jaw and molar of_, 327 Plagioclastic feldspars, 501 _Plagiostoma giganteum,_ Lias, 354 —— _Hoperi,_ Chalk, 300 _Planorbis discus,_ Bembridge, 253 —— _euomphalus_, 55, 255 Plants of Bovey Tracey, Miocene, 247 ——, fossil fresh-water, 57 —— of the Coal, 420 —— of the Lias, 364 —— of the Swiss Upper Miocene, 219 Plas Newydd, rock altered by dike near, 515 Plastic Clay, Eocene, 267 _Platanus aceroides,_ Miocene, 221 _Platystoma Suessii,_ Hallstadt, 377 Playfair, on amount of subaërial denudation, 114 —— on faults, 87 _Plectrodus mirabilis,_ Ludlow, 460 _Plesiosaurus dolichodeirus,_ Lias, 361 _Pleurotoma attenuata,_ Bracklesham, 262 —— _exorta,_ Eocene, 57 _Pleurotomaria anglica,_ and cast, 66 —— _carinata (flammigera)_, 434 —— _granulata,_ Inferior Oolite, 351 —— _ornata,_ Inferior Oolite, 351 Plieninger, Professor, on Triassic mammifer, 368 Pliocene glacial formations, 189-92 —— Period, 189 —— plutonic rocks, 565 —— strata of Sicily, 204 ——, term defined, 143 —— volcanic rocks, 529 Plombières, alkaline waters of, 585 Plumbago of Massachusetts, 583 Plutonic and sedimentary formations, diagram of, 567 ——, origin of the term, 551 —— rocks, Mesozoic, 570 ——, Recent and Pliocene, 565 ——, Miocene and Eocene, 568 ——, uncertain tests of age of, 564 —— defined, 31 _Podocarya Bucklandi,_ Oolite, 348 _Polypterus_ of the Nile, 444 Polyzoa and Bryozoa, terms explained, 197 Pomel, M., on fossil mammalia of the Limagne, 235 Ponza Islands, globiform pitchstone of, 512 _Porites pyriformis,_ Devonian, 451 Porphyritic granite, 556 Porphyry, 506 Portland, Cycads in dirt-bed of, 331 —— oolite and sand, 334 “_Portland screw,_” a cast of a shell, 335 Porto Santo, marine shells in volcanic tuff of, 536 Post-pliocene period, climate of the, 161 —— mammalia, teeth of, 163 ——, term defined, 145 —— lakes of Switzerland, 185 —— volcanic rocks, 524 _Potamides cinctus_, 56 _Pothocites Grantonii,_ coal-measures, 429 Potsdam Sandstone, 480, 489 Pot-stones in the Chalk, 290 Pottsville, coal seams of, 400 Powrie, Mr., on Cephalaspis beds, 446 ——, on Parka decipiens, 448 Pratt, Mr., on Eocene Isle of Wight mammalia, 254 Predazzo, altered rocks at, 571 Pressure, solidifying rocks, 65 Prestwich, Mr., on age of Sables inferieurs, 276 ——, on Chillesford beds, 192 ——, on Coalbrook Dale insects, 405 ——, on Eocene strata, 267, 269 ——, on faults in coal-measure of Coalbrook Dale, 88 ——, on shells of London clay, 264 ——, on thickness of Coralline Crag, 198 Prévost, M. Constant, on Paris basin, 270 Primary Limestone, 579 —— rocks, 458 ——, term defined, 123 “Primordial Zone” of Bohemia, 481, 482 _Productus horridus,_ Permian, 388 —— _semireticulatus (antiquatus)_, 434 Progressive development indicated by low grade of early mammals, 384 Proteaceæ of Aix-la-Chapelle flora, 304 —— of Lower Molasse, Switzerland, 237 —— of Œningen beds, 221 Protogine, 578 Protosaurus of Thuringia, 390, 464 Protrusion of solid granite, 574 Provinces of animals and plants, 126 _Psammodus porosus_, 437 _Pseudocrinites bifasciatus,_ Silurian, 466 _Psilophyton princeps,_ Devonian, 455 Pteraspis in Lower Ludlow shale, 463 _Pterichthys,_ Old Red Sandstone, 445 Pterodactyl of Kentish chalk, 297 _Pterodactylus anglicus,_ Old Red, 447 —— _crassirostris,_ Solenhofen, 337 _Ptychodus decurrens,_ White Chalk, 297 Pudding-stone or conglomerate, 36 ——, formation of, 62 Pumice, 508 Punfield beds, brackish and marine, 318 _Pupa muscorum_, 155 —— _tridens,_ Loess, 56 —— _vetusta,_ Coal, 415 Purbeck beds, Upper, Middle, and Lower, 323, 324, 336 ——, fossil mammalia of the Middle, 325 —— marble, 324 ——, subdivisions of the, 333 Purity of coal, cause of, 402 _Purpura tetragona,_ Red Crag, 196 _Purpuroidea nodulata,_ Great Oolite, 345 Puy de Côme, cone and lava-current of, 528 —— de Tartaret, lava-current and cone of, 527, 542 —— de Pariou, crater of the, 529 Puzzuoli, elevation of land at, 525 _Pygopterus mandibularis,_ Permian, 390 Pyrenees, chalk altered by granite in the, 570 ——, curved strata in, 86 ——, lamination of clay-slate in, 596 Pyroxene group of minerals, 499, 502 _Pyrula reticulata,_ Crag, 200

QUADER-SANDSTEIN, Cretaceous age of the, 293 Quadrumana of Gers, 215 Quadrupeds, extinct, in Paleolithic gravels, 152 Quartz, specific gravity of, 499, 500, 555 Quartzite or Quartz Rock, 579 Queenaig, unconformable Palæozoic strata at, 112 Quenstedt on zones of Lias, 353

RADABOJ Miocene, brown coal of, 242 _Radiolites foliaceus,_ White Chalk, 306 —— _Mortoni,_ White Chalk, 295 —— _radiosa,_ White Chalk, 306 Radnorshire, stratified trap in, 549 Rain-prints with worm tracks in Coal, 416 ——, carboniferous, 416 Ramsay, Professor, on break between Upper and Lower Cretaceous, 301 ——, on breccias in Permian, 391 ——, on escarpments, 104 ——, on denudation, 98 ——, on ice-erosion of lake-basins, 184 ——, on Lingula Flags, 484 ——, on position of Tremadoc beds, 483 ——, on Silurian metamorphic rocks, 602 ——, on submergence in glacial period, 181 ——, on thickness of the Lower Trias, 372 ——, on thickness of Llandeilo beds, 475 ——, on thickness of the Bala beds, 473 ——, on volcanic tuffs of Snowdon, 549 ——, on zones of the Lias, 353 _Rastrites peregrinus,_ Llandeilo Flags, 473 Rath, Von, on Tridymite, 500 Recent Period defined, 145 —— volcanic rocks, 524 Record, imperfection of, in the earth’s crust, 138 Red Crag, older Pliocene, 194 —— Sandstone, Origin of, 374 —— Sea and Mediterranean, distinct species in, 127 Redruth, Cornwall, section of veins in mine, 607 Reindeer Period in South of France, 149 Relistran mine, pebbles in tin of, 609 Reptiles of the Coal, 406, 413 Reptiles of the Lias, 360 _Retepora flustracea,_ Permian, 388 Rhætic beds between Lias and Trias, 366 Rhine, fresh-water strata of the, 53 ——, loess of the, 154 Rhinoceros in drift of Abbeville, 153 —— _leptorhinus (megarhinus),_ molar of, 164 —— _tichorhinus,_ molar of, 164 Rhode Island, metamorphic rocks of, 583 _Rhynchonella navicula,_ Ludlow, 460 —— _octoplicata,_ White Chalk, 294 —— _spinosa,_ Inferior Oolite, 350 —— _Wilsoni,_ Aymestry, 462 Richmond, Virginia, Triassic coal-field of, 382 Rigi and Speer, Lower Miocene of the, 235 _Rimula clathrata,_ Great Oolite, 345 Rink, Mr., on Greenland land-ice, 171 Ripple-marked sandstone, how formed, 46 Rise and fall of land, 146 _Rissoa Chastelii,_ Hempstead beds, 245 Rivers, denuding powers of, 101, 114 Roches moutonnees described, 169 Rock, term defined, 26 Rocks altered by volcanic dikes, 514 —— altered by subterranean gases, 586 ——, analysis of minerals in, 499 ——, aqueous or stratified, 27 ——, classification of, 121 ——, great thickness of palæozoic, 110 ——, glacial scorings on, 169 ——, metamorphic, age of, 597 ——, plutonic age of, 564 ——, volcanic, age of, 520 ——, trappean, 497 ——, metamorphic, defined, 32 ——, four classes of contemporaneous, 33 ——, plutonic, defined, 31 ——, tests of age of, 123, 125, 520, 564, 597 ——, four contemporaneous classes of, 122 ——, underlying, not always the oldest, 122 ——, volcanic, defined, 29 Rock-salt of Trias, 371 ——, origin of, 374 Rogers, Mr. H. D., on blending of coal-seams, 400 ——, on Virginian fault, 92 Rose, Gustavus, on isomorphism, 502 ——, on Fifeshire dike, 546 ——, on quartz in granite, 555 Rosso antico, red porphyry of Egypt, 506 _Rostellaria (Hippocrenes) ampla,_ London Clay, 266 Roth, M., on Miocene of Greece, 226 Runn of Cutch, salt of, 375 Rupelian beds of Dumont, 241, 242 Russia, glaciation of, 174 ——, Devonian of, 454 ——, Silurian strata of, 478

SAARBRUCK, reptiles in coal-field of, 406 _Sabal major,_ Lower Miocene, 237 Sables de Bracheux, 276 —— moyens, Paris basin, 273 Sahlite, 502 St. Abb’s Head, curved strata of, 76 ——, unconformable stratification at, 94 St. Andrews, carboniferous trap-rocks of, 545 St. Cassian, fossil mollusca of, 377 —— and Hallstadt beds, 376 St. David’s, Menevian beds of, 485 St. Mary’s, shells of, 539 Salt, rock, origin of, 372 Salter, Mr., on fossils of Arenig group, 476 ——, on Menevian beds, 485 ——, on Tremadoc fossils, 483 Sandberger, Dr. F., on Mayence basin, 242 Sandstone, New Red, 369 ——, Old Red, 439 —— slab with cracks, 317 ——, slab of ripple-marked, 45 —— slab with footprints, 408 _Sao hirsuta_, 488 Saurians of the Lias, 361 ——, sudden destruction of, 362 _Saurichthys apicalis,_ Rhætic Beds, 367 Saussure, on vertical conglomerates, 73 _Saxicava rugosa,_ Scotch drift, 176 Saxony, beds of minerals in, 609 Scandinavia, glaciation of, 174 _Scaphites æqualis,_ Chloritic marl, 299 Scapolite, 506 Scheerer on action of water in metamorphism, 585 Schist, mica, 578 ——, argillaceous, 579 ——, hornblende, 578 _Schizodus Schlotheimi,_ Permian, 387 —— _truncatus,_ Permian, 387 Schmerling, Dr., on Liége caverns, 157 Schorl-rock, and schorly granite, 557 Schwab, M., on Celtic coins in lake-dwellings, 149 _Scoliostoma,_ St. Cassian, 377 Scoresby, on Arctic icebergs, 172 Scoriaceous lava, 507 Scoriæ, 508 Scotland, “Fundamental gneiss” of, 493 ——, Old Red Sandstone of, 440 ——, glaciation of, 175 Screws, fossil, internal casts of shells, 66 Scrope, Mr., on Isle of Ponza, globiform pitchstone, 512 ——, on minerals in lava, 524 ——, on water in lava, 555 Scudder, Mr., on Devonian insects of Canada, 457 Sea, apparent fall of, caused by rise of land, 70 ——, denuding power of the, 105 ——, deep soundings in, 287 ——, mean depth of the, 118 —— cliffs, inland, 103 Secondary and Tertiary, gap between the, 281 ——, term defined, 123 Section of Auvergne alluvium, 100 —— of carboniferous rocks, Lancashire, 85 —— of chalk and greensand, 287 —— of crags near Woodbridge, Suffolk, 198 —— of cross-stratification, 42-44 —— of curved strata of the Jura, 82 —— of dirt-bed in Isle of Portland, 332 —— of Forfarshire, showing curved strata, 74 —— of fossil tree, showing texture, 67 —— of folded and denuded carboniferous beds, Nova Scotia, 418 —— of the Oolitic strata, 322 —— of Recent and Post-pliocene alluvial deposits, 151 —— showing creeps in coal-mines, 79 —— of slaty cleavage, 589 —— showing valleys of denudation, 98 —— showing the Weald formation, 313 —— of strata thinning out, 41 —— of superimposed groups at Dundry Hill, 130 —— of unconformable strata near Mons, 95 Sections illustrating faults, 88, 90, 91 Sedgwick, Professor, on the Cambrian Group, 481, 482, 486 ——, on classification of Arenig group, 476 ——, on Devonian series, 439, 449 ——, on position of the May-Hill beds, 568 ——, on protrusion of solid granite, 574 ——, on slaty cleavage, 588, 591 ——, on garnet in altered rock, 515 ——, on concretionary structure, 63 Sediment, accumulation of, causing a shifting of the subterranean, 117 isothermals. Sedimentary beds of the Carboniferous, 396 Selsea Bill, erratics at, 182 Senarmont on action of water in metamorphism, 585 _Sequoia Langsdorfii_, 238 _“Seraphim,” head of Pterygotus anglicus_, 446 Serapis, marine littoral deposits of, 146 Serpentine, 578 _Serpulæ_ attached to _Gryphæa_, 48 —— attached to _Spatangus_, 49 —— attached to _Apiocrinus_, 343 Shale defined, 36 —— of the Lower Ludlow, 461 Sharpe, Mr. D., on American Silurian fossils, 479 ——, on fossils distorted by cleavage, 592 Shell-mounds of Denmark, 146 Shells, Arctic, in Scotch drift, 177 ——, derivative, in the Crag, 195-203 ——, marine, found at great heights above the sea, 29 ——, proportion of living, in the Crags, 194, 195, 199 ——, value of, in classification, 142 ——, fossil, of Virginia, 228 —— of the London clay, 266 —— of the mountain limestone, 433 —— of the Barton clay, 258 —— of the Oolite, 335, 345, 350 ——, marine, of Moel Tryfaen, 180 Sheppey, fauna and flora of, 264 ——, Eocene fish of, 267 Sherringham, erratic block at, 191 Shetland, granite of, 558 ——, hornblende-schist of, 583 Sicily, fauna and flora of, older than the country itself, 207 ——, newer Pliocene strata of, 204 ——, subterranean igneous action in, 569 ——, undulating gypseous marls of, 86 ——, volcanic dikes of, 531 Sidlaw Hills, trap of, 548 Sigillaria in coal-measures, 380, 411, 425 _Sigillaria lævigata,_ coal-measures, 426 Siliceous limestone defined, 37 Silurian, derivation of the name, 458 ——, granite of Norway, 573 ——, metamorphic, of North Highlands, 601 —— rocks, classification of, 458 —— strata of the continent of Europe, 477 —— strata of United States, 478 —— volcanic rocks, 548 _Siphonotreta unguiculata,_ obolus grits, 478 Siwâlik Hills, fresh-water deposits of, 226 Skaptar Jokul, flow of lava from, 523 Skye, hypersthene rocks of, 491 ——, Isle of, Miocene syenite of the, 568 ——, trap dike in, 514 Slaty cleavage, 588 Slicken-sides, in opposite walls of veins, 608 ——, term defined, 87 _Smilax sagittifera,_ Œningen, 222 Smith, Mr. W., on White Lias bed, 366 Snowdon, volcanic tuffs of, 549 Soissonnais sands, 275 _Solenastræa cellulosa,_ Brockenhurst, 257 Solenhofen stone, fossils in the, 337 Solfatara, decomposition of rocks in the, 586 Somma, cone and dikes of, 526 Sopwith, Mr. T., models of outcrop of strata, 85 Sorby, Mr., on action of water in metamorphism, 585 ——, on glass cavities in quartz, 555 ——, on mechanical theory of cleavage, 592 ——, on ripple-marks in mica schist, 596 South Joggins, section of cliffs at, 410 Spalacotherium, Purbeck, 346 _Spatangus radiatus,_ Chalk, 284 —— with serpula attached, 49 Species, gradual change of, 139 —— older than the land they inhabit, 207 ——, similarity of conditions causing reappearance of, 311 Specific gravity of basalt and trachyte, 504 Speer and Rigi, Lower Miocene of the, 235 Speeton Clay, 311 _Sphærexochus mirus,_ Silurian, 467 _Sphærulites agariciformis,_ White Chalk, 306 —— of volcanic minerals, 499 _Sphenophyllum erosum,_ Coal, 425 _Sphenopteris gracilis,_ Hastings sands, 318 Spheroidal concretions in limestone, 64 _Spicula of sponge,_ Atlantic mud, 288 _Spirifera disjuncta,_ Devonian, 450 —— _alata,_ Permian, 388 —— _mucronata_, 454 —— _trigonalis,_ and _S. glabra_, 434 _Spiriferina Walcotti,_ Lias, 355 _Spirolina stenostoma,_ Eocene, 275 _Spirorbis carbonarius,_ coal-measures, 405 _Spondylus spinosus,_ White Chalk, 294 _Sponge in flint from White Chalk_, 296 Sponges, vitreous, in the chalk, 291 Springs, mineral of Auvergne, 604 Staffa, age of columnar basalt of, 539 Stalactite, origin of, explained, 156 _Starfish_ in Silurian strata, 472 Stations of species affecting distribution of fossils, 354 _Stauria astræiformis_, 431 Stereognathus of Stonesfield, 348 Sternberg, Count, on insects in coal, 495 _Stigmaria attached to trunk of Sigillaria_, 427 —— in coal-measures, 398, 411, 426 —— _ficoides_ and surface showing tubercles, Coal, 427 Stilbite, 500 Stiper-Stones or Arenig Group, 475 Stockwerk, assemblage of veins, 605 Stonesfield slate, mammalia of the, 345 Strata, term defined, alternations of fresh-water, and shallow and deep, 27 sea. ——, alternations of marine and fresh-water, 108 ——, curved, inclined, and vertical, 73 ——, apparent horizontality of inclined, 81 ——, contorted in drift, 178 ——, contortion of, in Cyclopean Isles, 530 ——, general table of fossiliferous, 131 ——, horizontality of, 40 ——, origin of metamorphic, 83 ——, overlapping, 95 —— repeated by being doubled back, 87 ——, slow growth of, attested by fossils, 47-50 —— of organic origin, 51 ——, tests of age of, 123 ——, unconformability of, 94, 138 ——, vast thickness of, not forming high mountains, 109-13 Stratification, diagonal or cross, 42, 44 ——, different forms described, 39 —— of metamorphic rocks considered, 580 Stratified rocks, composition of, 35 Striæ, production of, 168 Strickland, Mr., on thickness of the Trias, 369 _Stricklandinia lirata_, 469 Strike, term explained, 80 _Stringocephalus Burtini_, 452 Stromboli, lava of, 566 _Strophomena depressa,_ Wenlock, 466 —— _grandis_, 471 Studer, Mr., on gneiss of the Jungfrau, 599 subaërial denudation, average annual amount of, 113 Subapennine beds, proportion of recent species in, 143 —— strata, older Pliocene, 208 Submarine denudation, 105 Subsidence of land must preponderate over upheaval, 116 _Succinea amphibia_, 55 —— _elongata_, 155 Suess, M., on fossils of St. Cassian beds, 376, 377 ——, on Vienna basin, 225 Suffolk, Crag of, 195 “Sunk country,” New Madrid, 402 Superga, Lower Miocene of the, 244 Superior, Lake, marl in, 63 Superposition of deposits, a test of age, 124 —— a test of age of volcanic rocks, 521 Sutherlandshire, unconformable Palæozoic strata in, 112 Swanage, fossil mammalia found at, 326 Sweden, Cambrian of, 489 ——, slow rise of land in, 72 ——, small thickness of Silurian strata in, 477 Switzerland, lake-dwellings of, 148 ——, Lower Molasse of, 235 ——, Middle or Marine Molasse of, 223 ——, Upper Miocene of, at Œningen, 215 Sydney coal-field, rain-prints in, 416 Syenite, composition of, 552, 557 ——, how far connected with trap-rocks, 558 Syenitic granite, 557 Symonds, Rev. W. S., on Moel Tryfaen shells, 180 Synclinal and anticlinal curves, 74, 85

TABLE of Botanical Nomenclature, 303 —— of St. Cassian fossil mollusca, 377 —— of Cretaceous formations, 283 —— of Devonian series in Devon, 449 —— of divisions of Hastings Sand, 316 —— of English and French Eocene strata, 252 —— of ages of fossil vertebrata, 464 —— of Neocomian strata, 308 —— of mammalia older than Paris gypsum, 329 —— of marine testacea in the Crag, 202 —— of Oolitic strata, 321 —— of volcanic minerals, 499 —— of Silurian strata of United States, 478 —— of Silurian rocks, 458 —— of Triassic strata, 375 —— of Cambrian strata, 482 —— of Permian of north of England, 386 —— of Welsh coal-measures, 394 —— of thicknesses of Carboniferous limestone, 395 ——, general, of fossiliferous strata, 131 Table Mountain, granite veins in clay-slate of, 560 Tails of homocercal and heterocercal fish, 389 Talcose granite, 557 —— gneiss, 578 Tarannon shales, 468 Tartaret cone, and lava of, 527, 542 Tate, Mr., on St Cassian fossils, 377 Tealby series, Middle Neocomian, 312 Teeth of extinct mammalia, 163, 164 _Tellina balthica (T. solidula)_, 190 —— _calcarea (T. proxima)_, 177 —— _obliqua,_ Crag, 194 _Temnechinus excavatus_, 200 _Temnopleurus excavatus_, 200 _Tentaculites annulatus,_ Silurian, 489 _Terebellum fusiforme,_ Barton, 259 —— _sopita,_ Barton, 259 _Terebratula affinis,_ Aymestry, 462 —— _biplicata,_ White Chalk, 294 —— _carnea,_ White Chalk, 294 —— _digona,_ Bradford clay, 345 —— _fimbria,_ Inferior Oolite, 350 —— _hastata,_ Mountain Limestone, 434 —— _sella,_ Neocomian, 310 —— _Wilsoni,_ Aymestry, 462 _Terebratulina striata,_ White Chalk, 294 _Terebrirostra lyra,_ Chloritic Sand, 300 _Teredo navalis,_ boring wood, 50 Tertiary formations, classification of, 137, 143 —— strata, subdivisions of, 143 ——, term defined, 123 Testacea. _See_ Shells. Thallogens, 303 _Thamnastræa,_ Coral Rag, 339 Thanet sands, 269 _Theca operculata,_ Tremadoc beds, 483 _Thecodontosaurus, tooth of,_ 374 _Thecodus parvidens,_ Ludlow, 460 _Thecosmilia annularis,_ Coral Rag, 339 Thirria, M., on Nerinæan limestone, 340 Thompson, Dr., on Nummulites of Thibet, 277 Thomson, Wyville, on Atlantic mud, 288 ——, on sponges in chalk mud, 292 Thuringia, monitor of, 390, 463 Thurmann, M., on Bernese Jura Oolite, 344 ——, on structure of the Jura, 83 _Thylacotherium Prevostii,_ Stonesfield, 347 Tile-stones of the Upper Ludlow, 459 Tilgate forest, fossil Iguanodon in, 315 Till described, 166 ——, mammoth in Scotch, 175 —— of North America, 182 Tin veins, age of, in Cornwall, 615 Titanoferrite, 500 Torell, Dr., on ice-action in Greenland, 172 ——, on Swedish Cambrian fossils, 489 Touraine, faluns of, 211 Tourmaline, 500 Trachytic rocks, 505 —— tuff, 506 —— porphyry, 506 —— lava, age of, 523 Trap, term defined, 498 —— dike, intercepting strata, 518 —— dikes, 513-17 ——, intrusion of, between strata, 517 —— rocks, ages of, 524-50 —— rocks passing into granite, 559 —— tuff described, 508 Trappean rocks, nomenclature of, 497 —— rocks, their relation to active volcanoes, 517 Trass of Lower Eifel, 535 Travertin, how deposited, 60 ——, inférieur of Paris basin, 273 _Tree ferns, living_, 422 Trees erect in coal, Nova Scotia, 411 Tremadoc slates and their fossils, 482 Tremolite, 499, 502 Trenton limestone, fossils of the, 479 Trezza, volcanic rocks of, 529 Trias, beds of passage between Lias and, 366 —— of England, 369-74 —— of Germany, 375 ——, Saurians of the, 370 —— of the United States, 381 Triassic mammifer, North Carolina, 383 Triclinic feldspars, 501 Tridymite, crystallised silica, 500 _Trigonellites latus,_ Kimmeridge clay, 336 _Trigonia caudata,_ Neocomian, 310 —— gibbosa, Portland stone, 335 _Trigonocarpum ovatum,_ and _T. olivæforme,_ Coal, 429 _Trigonotreta undulata,_ Permian, 388 Trilobites of Bala and Caradoc beds, 471 ——, metamorphosis of, 471, 488 —— of primordial zone, 487 _Triloculina inflata,_ Eocene, 275 Trimmer, Mr., on contorted strata, 179 ——, on shells of Moel Tryfaen, 186 _Trinucleus concentricus, T. Caractaci_, 472 _Trionyx, carapace of,_ Bembridge, 253 Tripoli composed of diatomaceæ, 51 _Trochoceras giganteus,_ Ludlow, 463 _Trophon antiquum (Fusus contrarius)_, 196 —— _clathratum,_ Scotch drift, 176 Tuff defined, 30 ——, shelly, of the Grand Canary, 538 ——, trappean, of Llandeilo rocks, 473 ——, shelly, of Gergovia, 542 _Tupaia Tana,_ recent, 347 Turner, Dr., on chemical decomposition, 68 _Turrilites costatus,_ Chalk, 299 _Turritella multisulcata,_ Bracklesham, 262 Tuscany, mineral springs of, 604 Tylor, Mr., on amount of subaërial denudation, 114 Tyndall, Dr., on slaty cleavage, 594 Tynedale fault, 90 Tynemouth cliff, brecciated limestone of, 387 _Typhis pungens,_ Barton clay, 259

_UNCITES Gryphus,_ Devonian, 452 Unconformability of strata, 94, 138 Underlying, term applied to plutonic rocks, 34 Unger on American forms in Swiss Miocene flora, 223, 239 —— on Miocene plants of Croatia, 243 Ungulite, or Obolus grit of Russia, 477 _Unio littoralis_, 54 —— _Valdensis,_ Hastings Sands, 317 United States, Cambrian of the, 489 ——, Cretaceous rocks of, 307 ——, Devonian of, 455 ——, Eocene strata in the, 278 ——, footprints in Carboniferous of, 407 ——, Lower Miocene of, 248 ——, older Pliocene and Miocene formations of, 227 ——, Silurian strata of, 478 ——, Trias of the, 381 Upheaval of land more than counteracted by subsidence, 116 ——, power of denudation to counteract, 105, 115 Upper Greensand, or Chloritic series, 298 Upsala, erratics on modern marine drift near, 174 Ural Mountains, auriferous alluvium of, 616 Uralite, 499 _Ursus spelæus, tooth of_, 165 Urville, Captain de, on size of icebergs, 172

VAL D’ARNO, Newer Pliocene of, 207 Valleys, origin of, 102 Valorsine, granite veins in talcose gneiss in, 599 _Valvata piscinalis_, 55 _Vanessa Pluto,_ Lower Miocene, Croatia, 243 Vegetation of the Coal, 420 —— of the Devonian of America, 455 ——. _See_ Plants. Veins, chemical deposits in, 612 ——, granite rocks altered by, 559 ——, different kinds of minerals, 605 ——. _See_ Mineral veins. Vein-stones, 610 _Venericardia planicosta_, 260 Venetz, M., on Alpine glaciers, 170 _Ventriculites radiatus,_ Chalk, 292 Verneuil, M. de, on Russian Silurian, 462 ——, on Permian flora, 392 Vertebrata, progress of discovery of fossil, 464 Vertical strata, 73 Vesuvius, Recent and Post-pliocene volcanic rocks of, 525 ——, basaltic lavas of, 508 ——, tufaceous strata of, 522 ——, dikes of, 527 _Vicarya Lujani,_ Punfield, 319 Vicentin, columnar basalt of the, 511 Vienna Basin, Upper Miocene beds of, 224 Vine in Upper Miocene beds at Œningen, 221 Virginia, eighty miles of fault in, 92 ——, coal-field of, 382 Virlet, M, on corrosion of rocks near Corinth, 586 ——, on Cretaceous traps of Greece, 544 ——, on fossils in veins, 608 ——, on volcanic rocks of the Morea, 544 Volcanic ash or tuff, 508 —— breccia, 509 —— dikes, 513-16 —— force and denudation opposing powers, 117 —— mountains, structure and origin of, 494 Volcanic rocks defined, 29 ——, mineral composition of, 498 ——, Recent and Post-pliocene, 524 ——, Pliocene, 529 ——, Miocene, 536-43 ——, Eocene, 543 ——, Cretaceous and Liassic, 544, 545 ——, New Red, Permian and Carboniferous, 545 ——, Old Red Sandstone, 547 ——, Silurian, Cambrian and Laurentian, 548, 549 —— of Auvergne, 540 ——, columnar and globular, structure of, 510 —— of Grand Canary, 528 —— of Silurian age, 477 ——, special forms of structure of, 506 ——, tests of age of, 520-4 Volcanoes, extinct, 30 —— of Auvergne, 495 _Voltzia heterophylla,_ Bunter, 380 _Voluta ambigua,_ Barton clay, 259 —— _athleta,_ Barton, 259 —— _Lamberti,_ coralline and Red Crag, 196 —— _Lamberti,_ faluns, 214 —— _nodosa,_ London clay, 266 —— _Selseïensis,_ Bracklesham, 262 Von Buch, Leopold, on “elevation craters,” 496 ——, on Silurian plutonic rocks, 572

WACKE described, 508 Wagner, M., on Miocene of Greece, 226 _Walchia piniformis,_ Permian, 392 Wales and England, glaciation of, 180 Wallich, Dr., on Atlantic mud, 287 Water, denuding power of running, 98, 115 ——, action of, in metamorphism, 584 Watt, Gregory, on fusion of rock, 584 Weald clay and its fossils, 317 Wealden area, thickness of the, 319 —— formation, 313 —— flora, 320 Webster, Mr. T., on Tertiary strata, 141 Wellington Valley caves, 158 Wenlock formation, fossils of the, 465-8 —— limestone, 465 —— shale, 467 Werner on mineral veins in Saxony, 609 —— on isomorphism, 502 Westwood, Mr., on Lias beetles, 363 Wexford, veins of copper at, 615 Whitaker, Mr., on subaërial origin of escarpments, 104 White or coralline crag, 197 —— sand of Alum Bay, 38 Whymper, Mr., on Arctic Miocene plants, 240 Williams, Mr., on Cornish lodes, 607 Williamson, Professor, on Conifers of the Coal, 428 ——, on structure of calamite, 425 Wind, denuding action of the, 97 Wood, Mr. Searles, on Bridlington shells, 190 ——, on Chillesford and Aldeby beds, 192 ——, on shells of the Crags, 194, 195, 199 ——, on shells of Crag and faluns compared, 213 ——, on fish of Headon series, 255 ——, table of marine testacea of the Crag, 202 ——, on thickness of coralline crag, 198 Woodward, Dr., on St. Cassian fossils, 377 Woodward, Mr. H., on Pterygotus, 447 Woolhope beds, 467 Woolwich and Reading series, 267 Wright, Dr., on Barton shells, 258 ——, on zones of the Lias, 353 Wunsch, Mr. E. A., on trees in volcanic ash, 546 Wyville Thomson. _See_ Thomson.

_XIPHODON gracile,_ Paris basin, 271 _Xylobius Sigillariæ,_ Nova Scotia coal, 415

YOREDALE beds, thickness of the, 395 Yorkshire, Oolite of, 349 Young, Mr., on seeds washed out of mammoth tusks, 176

ZECHSTEIN of Germany, 392 Zeolites, secondary volcanic minerals, 500 _Zeuglodon cetoides,_ Eocene, United States, 280 Zircon-syenite, 558 _Zoantharia rugosa_ and _Z. aporosa_, 431 Zones of the Lias, 353 _Zonites priscus,_ Coal, 415 Zoological provinces, great extent of, 127 Zoophytes, fossil, 48 ——. _See_ Corals, Bryozoa, etc. Zurich, lake-dwellings in Lake of, 148