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Show 172 ISLAND LIFE. (rAHT I. . d t often of enormous angular blocks of serpentme an greens one . £ t size one bein(J' fourteen feet long, and another twenty-six ee . So~e of the oblocks were observed by Sir C~arles Lyell to be faintly striated and partly polished on one side, and they are tt d throu(J'h the beds for a thickness of nearly 150 feet. sea ere o . · h h bl k I t I·S m· t eres t'm g th a t the particular bed m wh1c t e . oc s occu. r yields no organic remains, though th~se are plentiful ?oth m h d l · ,. and overlyin(J' beds as 1f the cold of the 10ebergs t e un er yme o ' . . had driven away the organisms adapted to hve only m a co~- para tI.v e 1y wa rm sea . Rock. simila. r in kind to these erratJCs occurs about twenty miles distant m the Alp~. . . . The Eocene period is even more charactenst10ally trop10al m its flora and fauna, since palms and Cycadacere, turtles, sna~cs, and crocodiles then inhabited England. Yet on the north side of the Alps, extending from Switzerland to Vien~a, and also south of the Alps near Genoa, th~re is a deposit of finelystratified sandstone several thousand feet in thickness, quite destitute of organic remains, but containing in several places in Switzerland enormous blocks either angular or partly rounded, and composed of oolitic limestone or of gra~ite. . Near t~e Lake of Thun some of the granite blocks found In this deposit are of enormous size, one of them being 105 feet long, ninety feet wide, and forty-£. ve feet thick ! The granite is red, and of a peculiar kind which cannot be matched anywhere in the Alps, or indeed elsewhere. Similar erratics have also been founu in bells of the same aO'e in the Carpathians and in the Apennines, indicating probabl; an extensive inland European se~ into wh~c~ glaciers descended from the surrounding mountams, deposttlng these erratics, and cooling the water so as to destroy the mollusca and other organisms which had previously inhabited it. · It is to be observed that wherever these erratics occur they are alwavs in the vicinity of great mountain ranges; and although thes~ can be proved to have been in great part ~levated during the Tertiary period, we must also remember that they must have been since very much lowered by denudation, of the amount of which, the enormously thick Eocene and Miocene beds now forming portions of them is in some degree a measure as well as a proof. It is not therefore at all improbable that CHAP. IX.) ANCIEN'l' GLACIAL EPOCHS. 173 during some part of th e T er tI' ary pen.o d t h esc mountam. s may ha'.v e been £a r h'1 g h er than they are now, and this we know might be sufficient for the production of glaciers descending to the sea-level, even were the climate of the lowlands somewhat warmer than at present.l Th~ weight o~ th.e negative evidence.-But when we proceed to exam~ne the Tertiary deposits of other parts of Europe, and especially of our own country, for evidence of this kind not only is such evidence completely wanting, but the facts ~re of so definite a character as to satisfy most geologists that it can never have existed; and the same may be said of temperate North America and of the Arctic regions generally. In his carefully written pape~ on "The Climate 'controversy" Mr. Searles V. Wood, Jun., remarks on this point as follows: "Now the Eocene formation is complete in England, and is exposed in continuous section along the north coast of the Isle of Wight from its base to its junction with the Oligocene (or Lower. Miocene according to some), and along the northern coast of Kent from its base to the Lower Bagshot. Sand. It has been intersected by railway and other cuttings in all directions and at all horizons, and pierced by wells innumerable· while from its strata in England, France, and Belgium, th~ most 1 Prof. J. W: ,Judd says: "In the case of the Alps I know of no glacial phenomena whiCh are not capable of being explained like those of New Zealand, by a great extension of the area of the tracts ~trove the snow-line which w?uld c?llect more ample supplies for the gla~iers protruded into s~rroundmg plams. And when we survey the grand panoramas of ridges, pmnacleFJ, and peaks produced for the most part by sub-aerial action, we may .well be prepared to admit that before the intervening ravines and valleys were excavated, the glaciers shed from the elevated plateaux must have been of vastly greater magnitude than at present.'' (Contributions to the Study of Volcanoes, Geological Magazine, 1876, p. 536.) Professor .:rudd applies these remarks to the last as well as to previous glacial periods \the Alps ; but surely there has been no such extensive alteration and lowering of the surface of the country since the erratic blocks were deposited on the Jura and the great moraines formed in North Italy a.s this theory would imply. Vl e can hardly suppose wide areas to ha~e been lowered thousands of feet by denudation, and yet have left other adjacent areas apparently untouched ; and it is even very doubtful whether such an extension of the snow-fields would alone suffice for the effects which were certainly produced. |