348 D. Jones—Coal-measures of the Brown Che Sill.

TV.—Osr THE CARBONIFEROUS DEPOSIT OF THE BROWN OLBB HILL AND ITS BELATION TO CONTIGUOUS COAL-FIELDS. By T>. JOKES, F.G.S. rPHE Coal-measures of the Brown Clee are of themselves ex- I tremely insignificant and unimportant. The total area is limited, and the thickness of the coals would not have entitled them to be considered of commercial value, if it were not for the fact, that from its elevated position it is placed well above the reach of water, and hence the great difficulties which beset early mining operations in freeing the mines from water did not affect the coal-mines of the Brown Clee; consequently, in those times they were worked to advantage, but there is very little coal remaining to be won. They have, however, a value to the geologist, as indicative of the much wider range of the Coalbrookdale Coal-measures than is shown by its present boundary, for there is an unmistakable analogy between both deposits, to which, we shall presently refer.1 We are now at an elevation of 1730 feet above the level of the sea, upon the summit of a hill, which is surmounted with a capping of Jew-stone, and beneath it a patch of Coal-measures not exceeding a total thickness of 110 feet. Beneath that we have Millstone Grit, which, it has been stated, is 200 feet thick, but in my opinion is considerably less, and the Geological Survey have omitted to show that there is any whatever. Below that we get the whole base of the hill, consisting of Old Red Sandstone. This capping of Coal-measures is divided into two patches, occupying the two points of the hill known as Clee Burf and Abdon Burf. The presence of the Jew-stone, which is an igneous rock, at once gives us a clue to the cause of the singular elevation of these coal patches; and not only so, but explains to us how they have escaped the denudation which has overtaken a very large area of Coal- measures that once laid in a sheet around this site, the Jew-stone having acted from its hard and obdurate nature as a protector and breakwater against the incursion of the denuding waves. Immediately below this igneous rock we have a coal which is called the " Jew-stone Black Coal," which, with the intervening partings, measures about 4 feet. At 13 feet below this is found the Three- quarter Coal, measuring 2ft. 3in., and I should not forget to men- tion that between these two coals is a substance called by the miners " Black Bessy's Eyes," no doubt in honour of some belle in the miners' village long ago. Beneath the Three-quarter Coal, at a distance of 7ft. 9in., lies the " Batty Coal," whioh, with coal and partings, measures 5ft. 3in. At 63 feet below this we find the "Bottom Coal," 2ft. 4in. thick, •which sometimes rests upon the Millstone Grit, but more frequently has a few feet of Coal-measure intervening. Not far above the Bottom Coal lies the Ironstone, which was 1 Further details relating to these Coal-measures are given in a paper by Mr. D. Jones, published in the GEOL. MAO., Vol. VIII. p. 200. D. Jones—Coal-measures of the Brown Glee Sill. 349 formerly worked to a considerable extent, and carried into Bewdley Forest for the purpose of smelting. On a careful comparison of this section with that of the Cornbrook District, it appears there is an unmistakable identity, and these coals represent those of Cornbrook, ranging from the " Great Coal" to the "Four Feet Coal," but there is this remarkable difference in the rest of the deposits, that whereas the Bottom Coal of the Brown Clee (which is equivalent to the Four Feet Coal of Cornbrook) rests upon the Millstone Grit, we have at Cornbrook a thickness of 404 feet of Coal-measures below the Four Feet Coal, followed by the " Gutter Coal," and other measures, making a total of 454 feet between the Four Feet Coal and the Millstone Grit. The Millstone Grit is between 200 and 300 feet thick at Cornbrook, whereas at the Brown Clee it cannot exceed 50 feet at the most. The points of nearest contact between Cornbrook and Brown Clee Hill are .about three miles and a half apart, and it is a most remarkable thing that such a difference should exist with regard to the lower deposits. I may remark that at Harcott there is another patch of coals which correspond with those of Cornbrook and Brown Clee; but in that instance the coals rest immediately upon Old Eed Sandstone, •without any intervening Millstone Grit. How then does it happen that at Haicotfr and Brown Clee we have little or no Coal-measures underlying the equivalent of the Four Feet Coal, whereas we have so great a thickness at Cornbrook ? It seems to me that subsequent to the deposition of the Millstone Grit it was upheaved in the locality of Brown Clee and Harcott ;>it was then partially denuded at the Brown Clee, but at Harcott entirely denuded. In the low ground at Cornbrook, the " Gutter Coal" and Coal-measures under- lying the Four Feet Coal were accumulated, and then the Four Feet Coal was formed, this accumulation of Coal-measures raising the level of the Four Feet Coal sufficiently high to allow it to range over the elevated ground which Ve have referred to at Harcott and Brown Clee. I can see no other interpretation of this phenomenon, unless it •otrald be shown that the Harcott and Brown Clee Coals are the equivalents of the " Gutter Coal" of Cornbrook, but a careful com- parison of the sections shows distinctly that they are not; on the contrary, they all answer to the series lying between the Great Coal and Hie Four Feet Coal of Cornbrook. It is very interesting to trace the connexion of these patches, because it tends to elucidate phenomena which present themselves in the Coalbrodkdale fields, where a vast washing away of coal -strata has taken place, and has produced what is locally known as the Symon Fault. It has also washed off much of the deposits south of a line drawn from Ketley to Lilleshall. To a person travelling through Shropshire, and passing over the Coal-measures which may be seen distributed over several parts of the county, it might seem an extremely rich and productive coal district; but he would be grievously deceived if he placed the 350 D. Jones—Coal-measures of the Brown Clee Sill. district of Bewdley Forest in the list of productive coal-fields. That it once was the site of a rich and productive coal-field there can be no doubt, and this is testified by the remnant of productive Coal- measures found at Harcott; but the main original deposit has been removed by denudation, with the exception of that remnant and the patches at Brown Clee and Cornbrook. The void was subsequently filled up with Upper Coal-measures of the unproductive character which we know to exist in the Bewdley district. Seeing that the Millstone Grit thickens to the south-west, as at Cornbrook, and also the older Coal-measures, one is inclined to believe that in this direction we are passing from the high ground which forms the base of the Coal-measures at Coalbrookdale and in South Staffordshire into lower ground capable of receiving the Millstone Grit and a greater thickness of Coal-measures; and this being so, is very suggestive of the probable connexion at an earlier period of these coal-fields with those further, south, as, for instance, the Forest of Dean, where the deposits are of a similar character. In the neighbourhood of Cornbrook there are still considerable quantities of coal remaining unwrought, and previous to the exten- sion of railway communication it was a blessing of the highest importance to the district that this Coal-field had escaped denudation. It may seem, perhaps, surprising that the greater portion of the Cornbrook Coal-field is covered with Jew-stone, in some cases 150 feet thick, which has been poured out over the Coal-measures, and so protected them from denudation. This igneous rock is of considerable value as a paving-stone, and the nature of the Jew- stone at Brown Clee and Cornbrook seems to be precisely the same. They were probably contemporaneous ejections. I do not think it probable that they were injected between the strata of the Coal- measures in the same way as we find in South Staffordshire, where sheets of Basalt take the place of acres of coal. The Titterstone Clee is itself an ancient volcano, and probably was active at the time the Jew-stone was spread over the Coal-measures. Believing, as I do, that all these patches of older Coal-measures were once connected, and formed part and parcel of the Coalbrook- dale and South Staffordshire Coal-fields, I think there can be little doubt that the Coal-measures of Cornbrook and Brown Clee were at one time of infinitely greater thickness ; but previous to the deposit of the Jew-stone they must have been considerably denuded, because, so far as we can co-relate the Cornbrook deposits with those of Coalbrookdale, they are not more than half their thickness, so that the history of events which we have passed before us in review points to an uneven surface, upon which the Millstone Grit was deposited; changes of level and denudation at that time, subse- quently the deposition of Coal-measures and their accumulation, until the whole of the productive Coal-measures of Coalbrookdale and South Staffordshire were formed—and afterwards a vast denu- dation over the districts we are speaking of, which removed the greater part of this deposit, leaving only here and there islands to testify that they once had been. Then follows the deposit of the A. Anderson—On Changes of Climate. 351 Upper Coal-measures in these denuded hollows, first filling them up, then covering such islands of older Coal-measures as might remain. These statements may appear startling to those who have not made a study of the subject; but I can assure them that if they will mentally peel off the Upper Coal-measures, they will find beneath the vacuities produced by this denudation, and such islands of older Coal-measures as may have been left. They will find that they have exposed to view an ancient valley, and the gradually sloping side of the Coalbrookdale Coal-measures thickening as they retreat from the influence of the waters. Still further, if they will peel off the Old Coal-measures, they will find a surface where the hollows have been filled up with Millstone Grit, leaving higher ground of Silurian rock, and it is only by dealing with the subject in this way that one can realize to one's self the events which must have taken place. These truths, never- theless, are far less astounding than those which are unfolded to us by other sciences, and furthermore they are not statements which are invented to amuse, but they are truths upon which great com- mercial undertakings in mining are based.

V.—ON CHANGES OF CLIMATE AND EXTINCTION OP MAMMALIA.1 By ALEX. ANDERSON, Esq., J.P., Victoria, Vancouver. T has been argued by some that the seas were anciently cooler I than at the present day, and that thence certain ulterior effects might be assumed. Without treating of the supposed effects, I wish to state that the premiss itself seems to me inconsistent with what, geologically viewed, appears to be the order of transition through which our planet has passed in-its successive changes. My own un- professional view, founded upon grounds generally admitted, has been that, from a temperature originally much higher, the oceans had gradually cooled down under adequate influences to the mean temperatures which they now maintain under the permanent climatic conditions of the globe; and indeed that the peculiar condition dis- tinguished by geologists as the " Glacial Period " was but the effect of the rapid condensation of the vapours arising during the long- continued process of cooling, under a great and sudden organic change. I will not, however, dwell on this point, lest I should seem but to iterate arguments that have already proceeded from other sources.* Nevertheless, I venture further into the consideration of abstruse points connected therewith, in vindication of the position I 1 Communicated to Prof. Rupert Jones, F.R.S.,in a letter dated December 10th, 1870. 2 I make this remark because I met with a brief notice in the scientific columns of tbe London Illustrated News of August 13th, 1864, from which I learn that Prof. Frankland, in a then recent lecture, had enunciated views on this subject almost coincident with my own: and also that Prof. De la Rive, of Geneva, had pro- mulgated a similar opinion as far back as 1852. That I feel flattered by the support which my modestly conceived opinion receives incidentally from these high authorities, I need not add; and also that I am thereby rendered the less diffident in its ex- pression.