But a few years since geologists were in the habit of drawing largely from the Bank of time, and the more they drew the greater was the supply they seemed to want, till at last the thought seemed to come quite natural to them that the supply indeed was inexhaustible. Quite lately, however, these time-speculators have had it suggested to them that there is a limit to the supply, and that the countless ages on which they have depended seem to be very probably but some one hundred millions of years, and untold ages to be reckoned by telling numerals.

The igneous theory of the earth's crust, which supposes it to have been at one time a fused mass, and to still retain in its interior a great degree of heat, is now generally admitted. In order to explain the origin of eruptive rocks, the phenomena of volcanos, and the movements of the earth's crust, all of which are conceived by geologists to depend upon the internal heat of the earth, three principal hypotheses have been forward. Of these the first supposes that in the cooling of the globe a solid crust of no great thickness was formed, which rests upon the still uncongealed nucleus. The second hypothesis, maintained by Hopkins and by Poulett Scope, supposes solidification to have commenced at the centre of the liquid globe, and to have advanced towards the circumference. Before the last portions became solidified, there was produced, it is conceived, a condition of imperfect liquidity, preventing the sinking of the cooled and heavier particles, and giving rise to the superficial crust, from which solidification would proceed downwards. There would thus be enclosed, between the inner and outer solid parts, a portion of uncongealed matter, which, according to Hopkins, may be supposed still to retain its liquid condition, and to be the seat of volcanic action, whether existing in isolated reservoirs or subterranean lakes; or whether, as suggested by Scrope, forming a continous sheet surrounding the solid nucleeus, whose existence is thus conciliated with the evident facts of a flexible crust, and of liquid ignited matters beneath.

A Little time back there appeared in the Magazine, some short papers on the subject of faults, and on the nature of the conditions and the forces through which these important structural features may-have been produced. The points I would now bring to notice are more elementary; they refer to the evidence for faults; hence involving the principal data upon which the higher discussion of the phenomena must be based, and the same data very argely affect our attempted restoration and history of bygone phases of the earth's surface. Faults and flexures in stratified rocks are the leading features through which we interpret the disturbances that have affected the earth's crust; and any looseness in determining their existence, form and amount, must vitiate many of our inferences. No one but an experimental field geologist can appreciate the difficulty of such determinations, and understand how faults are particularly liable to elude observation. This circumstance accounts for, but does not justify, the arbitrary use of faults in interpreting sections. To call in question the evidence upon such a familiar subject implies, of course, dissatisfaction at the manner in which it is handled in practice. This I at once admit, and will proceed to explain. The criticism I have to make is no more than might oceur to one who had never left his study; but I would state that with me it has had a most practical origin: in the progress of the work of the Geological Survey of India, several great boundary faults have been proposed in connection with our main rock-series, and in some cases published descriptions have been already given; but both on the score of the in-sufficiency of the evidence brought forward, and after personal examination in the field, I am unable to admit that some of the features in question can, without very implicit qualifications, be brought within the received definitions of a fault.

It is now generally recognised that the power which forces up lava from a depth of miles through narrow and crooked fissures broken across the solid crust of the globe, is no other than steam, developed in the interior of the lava by vaporisation of water intimately disseminated throughout its substance. I am not aware that previously to the publication of my volume on Volcanos in 1825. But I had derived a conviction of 1822, and a study of Etna and Stromboli in the years 1819–21. This was subsequently confirmed by the discoveries of Sorby, Scheerer, and others, of the existence of water in intimate molecular combination with the crystalline or granular minerals that compose the granitic rocks from the fusion of which lava is supposed to proceed. I had expressed my belief that the aqueous particles so confined, whether in a liquid or a solid state, would upon the occurence of increased heat, or diminished pressure, exert an elastic separating force upon the solid crystals of granules, in the manner of a flux, and thus assist the liquefaction of the mass, and drive it up any fissure that might open for its passage, in a pasty or semi-liquid state, short of complete fusion; so that on reaching the outer air, and parting with the contained steam, together with the heat which the expansion of this element would carry off in a latent from, its surface would consolidate instantly; and the solidification extending rapidly inwards by the formation of crevices giving an outlet to further vapour, the resulting rock would exhibit a cellular or porous structure, and a granular or crystalline texture, in lieu of the compact and glassy one which, if completely fused, it should possess.

A Special interest has always attached itself in this country to the remains of that rare and bizarre carnivor, the Sabre-toothed tiger. For as yet it has only been indicated to us on this side of the Channel by the most fragmentary and unique specimens —the two teeth, incisor and canine, obtained by the Rev. Mr. MacEnery, from Kent's Hole, Torquay, the authenticity of which have even been doubted. Whilst, however, palæontologists have pretty generally come to the conclusion that these two isolated teeth are really the remains of a Devon Sabre-tooth, no further specimens have, I believe, been recorded from other caverns in this country.

The specimens placed in my hands by Mr. N. Plant from Rio Grande do Sul consist of a few specimens of coal and a considerable number of a highly ferruginous shale. The coal contains no recognizable fossils, but they abound in the shale. The substance of the plants is converted into a brittle coal, that possesses no structure, and exhibits the form only of the organism, but the superficial structure and the venation is often so beautifully preserved on the surface of the shale, when the coal is removed, that the nature of the fossils is very clearly exhibited. I have, thus, been able to determine with precision three species, and to recognise more vaguely a number of other forms, which, however, it would be injudicious, until additional material is obtained, to name or describe from the specimens in my possession. All these forms, as far as they can be determined, and certainly the three well-preserved species, belong to Palseozoio genera, species of which occur in the Coal-measures of Britain. We are thus enabled with certainty to refer the Coal-fields of the province of Rio Grande do Sul to the Carboniferous period, although the coal itself has more the aspect of being the product of a Secondary formation.

The following notes were made during a few days' leave of absence, spent chiefly on the Green-slate area of the Lake-district, the beds of which have an east-north-east and west-south-west direction of strike, extending across the country in a belt about fourteen, miles in width, resting on the Skiddaw Slates, and passing under the various divisions of the Coniston series. The characteristic feature of this tract of country is the uniformity in direction of all the gorges, or depressions, in which the lakes occur. The initiative of their direction (as pointed out by Dr. Nicholson) appears to have been given by a system of north and south faults: thus Windermere, Rydal Water, Grasmere, and Thirlmere may be said to lie in one line of depression. Between the two last-mentioned lakes the pass of Dunmail Raise forms a col between two valleys. In the bottom of the valley, between the pass and Grasmere, there are immense mounds of moraine, matter, the pebbles are all angular and strictly local. Steel Fell and Seat Sandal form two cliffs on either side, that on the western being much the steeper; the summit of Helm Crag, being much weathered, forming the well-known “couchant lion with a lamb under its nose,” of the guide books. Following up the ice marks of Easdale Valley into that of Raise Beck, there seems little doubt that the two glaciers occupying these valleys united between Silver How and Nab Scar, and thence bore down upon Loughrigg Fell, which stopped its forward progress in a direct line, deflecting it into what is now Rydal Water. The lake Grasmere is excavated in a rock-basin, and one can easily understand its excavation being due to the immense pressure of the ice infringing on Loughrigg Fell. A similar state of things took place at the foot of Rydal Water; the rocks here are moutonnèed and glaciated upwards.

Having in my last communication presented the most recent views entertained by M. Coquand, I now proceed to mention those held by Monsieur Hébert, a most experienced observer, who has made the “Cretaceous system” a subject of particulat study. M. Hébert considers that M. Coquand has sepatated the period into too many definite divisions (étages), and in two papers published in the Bullettin of the Geological Society of France (Vol. 16 and 20, 2nd series), his views upon that topic have been fully recorded. He had not, however, drawn up any complete scheme of classification, but this he has now kindly done at my request. (See Table of Classification.)

Having a short time since drawn up a brief statement of the evidences upon which the presumed antiquity of the human race in Western Europe is based, and also some account of the animals found associated with early man in this region, I have ventured to think it may be found of sufficient interest to lay before this Society.

For a considerable time I have taken much interest in the question of the origin of the narrow and deep valleys in the Carboni-ferous Limestone district of Derbyshire, and have carefully recorded whatever seemed to explain their formation. So far I have never met with more striking facts than those to be seen in Deep Dale, about three miles in a direct line E.S.E. from Buxton. I estimate the depth of the valley at about 100 feet, and its width at from 100 to 200 yards. At a distance of about a mile from the Bakewell road there is a cavern, which is especially conspicuous on the east side. Its entrance is about 6 feet high, 20 feet broad, and 40 feet above the bottom of the valley. It extends nearly horizontally for about 30 yards, and then descends to a lower level, where I did not further examine it. On looking from the entrance to the opposite side of the dale I was surprised to see what appears to be a continuation of the same cavern. The entrance on that side is at about 80 feet above the valley, and is so much blocked up with detritus that one can only examine it for a space of 10 yards. Taking, however, all the facts into consideration, it appears to me that at a very remote period a subterranean stream flowed continuously along these two caverns, from west to east. There is abundance of suitable gather ground on the west side which even now has no well-marked surface drainage, and from which much of the water probably escapes by a subterranean course, ending in the large spring in the main valley, by the road-side below Kingsterndale.

The number of the Geological, Magazine, for September last, contained a description, by Mr. James Geikie, of stratified beds of sand and mud intercalated with Boulder-clay, which occur in the Cowdon valley, near Crofthead. His reference to some contained vegetable débris induced me to make an examination of the strata, which has resulted in revealing an abundance of organic remains quite exceptional in such deposits.

For many years the various Coal-shales and other strata associated with the Coal-seams of Northumberland have been known to be rich in the remains of Plants, and the majority of the specimens which are illustrated in Lindley and Hutton's elaborate work on the Flora of the Coal-period were obtained from collieries in Northumberland and the adjoining county, Durham. It is only within the last few years that close attention has been directed to the investigation of the fauna of the Northumberland coal-fields. The first systematic investigator of the fauna of the Carboniferous period in this locality was Mr. Thomas Atthey, late of Cramlington, now of Gosforth; and within the last few years Messrs. Kirby, Sim, Taylor, and Craggs have each secured good collections of the Carboniferous fossils.

The accompanying section represents the passage of the Red Chalk, of Speeton, into an underlying bed of dark slaty clay.It exhibits a small section, which was visible in the cliff on the South of Speeton Beck, in September last.

The Skiddaw Slates, or Lowest Silurian Rocks of the Lake-district, are succeeded upwards by a great series of ashes with interbedded traps and porphyries, to which the name of “Green Slates and Porphyries” has been applied, and it has always been believed that the relations between the two were those of perfect conformity. As early, however, as the year 1867 I was led, from certain phenomena which I had observed, to express the opinion that “whether the Green Slates are really conformable with the Skiddaw Slates is a question which admits of doubt, though data are wanting to arrive at a definite conclusion.” (Geology of Cumberland and Westmoreland, p. 33.) In the beginning of November, 1868, I discovered what seemed to be a marked want of conformity between the Skiddaw Slates and the Green Slates, the localities where this occurred being the eastern side of the mouth of the vale of St. John, the west side of Derwentwater (near Lowdore), and the mouth of Borrowdale. As these phenomena had not been previously noticed by any former observer, and as they appeared to me to be of considerable importance, I have made a systematic investigation of the subject, and have arrived at the following results.

During my recent stay at Geneva the eminent geologists MM. F.J. Pictet and P. de Loriol showed me a very considerable number of fossils, which they had collected from the middle and lower portions of the Cretaceous system of Switzerland and Savoy, and carefully explained the position of the beds from which they had been obtained. M. Pictet subsequently, at my request, recorded in manuscript his most recent views in connection with this important topic, of which I will shortly reproduce a translation for the benefit of the readers of the Geological Magazine. He has, however, restricted his table and explanations to the middle and lower portions of the Cretaceous system, because the regions which surround Geneva do not exhibit any representatives or evidence in connection with the upper stages. M. Pictet has also explained his views with reference to the rock which, at the Porte-de-France, contains the Terebratula janitor, and of the Carpathian or Stramberg limestone, which has been placed by M. Hébert at the base of the Cretaceous system, but which others have referred to the Jurassic epoch. The correct determination of the true age of these rocks is a subject of very great importance, since they contain a rich assemblage of species bearing a particular and well-marked stamp, as may be seen by a glance at Professor Suess's admirable monograph, “Die Brachiopoden der Stramberger Schichten,” as well as at those by Zettel, etc., on other classes.

In the number of this Magazine for July, 1866, p. 293, I ventured to characterize as “preposterous,” the opinion advanced by Mr. D. Mackintosh in two preceding papers (Geol. Mag., Vol. III. p. 69, and p. 163) that the very numerous terraces that occur on the sides of the Chalk and Oolitic hills of the southern and western counties were, “without doubt, raised Sea-beaches,” affording, therefore, evidence of the very recent elevation of these hills from beneath the sea-level, since the complete excavation of the existing valleys.

At the commencement of the present year some considerable interest was excited at Cape Town through the announcement in the newspapers that coal had been discovered at the Cape, and pronounced by reputed competent authorities to be of very good quality. Very soon afterwards it was reported, however, that it was not coal but peat, or lignite, and of bad quality; but still the newspapers persisted in calling it “The Coal diggings.” I heard of the discovery on my first arrival at Cape Town, in April last, and resolved to visit the spot at the first opportunity. In the meantime I obtained some information, and also the name of the person who was super intending the working, and on April 24th went to the Klapmuts Station on the Cape Town and Wellington Railway, and walked across to the Joostenberg workings, about five miles from the station.

Previous to writing “Suggestions on Denudation,” I had not seen Mr. Darwin's paper “On the Formation of Soil;” since then, having read this essay, it appears to me that instead of Darwin proving “the disappearance of stones, etc., needs no growth of soil,” he advocates in a great measure the statement put forward in “Suggestions on Denudation.” For Darwin clearly proves that any foreign sustance placed on grass land will be gradually covered up by a growth of soil over it. This soil, however, he seems to believe to be entirely due to the labour of earth-worms, who excavate in the ground under the foreign sustance and deposit over it. From this it would appear that this eminent observer considers that the total thickness of the soil is not increased upwards by mould formed from vegetable decay, but that all is taken from below the foreign sustance and placed above it, thereby adding to the thickness of the upper stratum of the mould and diminishing the thickness of the portion below the foreign substance. This, within certain limits, may be correct; but can anyone asset that the decay of the yearly growth of vegetable matter is nil, and that it cannot possibly and its mite, no matter how small, to the thickness of the soil? If the above is the case, how can we account for the growth of peat bogs in Ireland and other countries? On the site of all peat bogs (or the bogs in the low flat country) there originally was vegetable soil, in which trees and lesser plants grew;—on this, by the decay of the vegetable matter, a spongy soil was formed that retarded the drainage, and was well fitted for the growth of such mosses as the Sphagnum, which began to luxuriate.

Denudation has been divided into only two kinds — viz., Subœnal and Marine; nevertheless, naturally there seem to be three marked denuding forces—I. Subœrial or Atmospheric; II. Marine; and, III. Glacial.1

No other part of Sweden affords more favourable opportunities for studying the earliest fossiliferous deposits and their relations to each other than Vestrogothia, with its unusually complete, undisturbed, and, in many natural sections, exposed series of strata. Its two lowest principal layers, consisting of sandstone and alum-slate, are to be referred to the Cambrian system, if that system, as proposed by Sir Charles Lyell, Salter, and others, be extended over the “Primordial zone,” which is easily distinguished by its organic remains from the overlying Silurian deposits. This sandstone has long been known as the oldest stratum of Vestrogothia above the Fundamental Gneiss. Traces of seaweeds were found in it by our earlier geologists, and caused it to receive the name, still commonly used, of Fucoid sandstone. Deposits of the same period are distributed over large parts of Scandinavia; and Professor Angelin, who, like his predecessors, had found them to be the oldest portion of the whole “Transition formation” of Scandinavia, included them all in his regio Fucoidarum, no other Fossil having as yet been found in them. Norwegian authors have proposed the denomination “Sparagmite stage,” for the rock prevailing in Norway, which has not as yet afforded any fossils, a term also adopted by Professor Torell.