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Show • ERA OF THE SUPERFICIAL FORMATIONS. inland. Then, upon another elev~tion, the sea began_ to form, at its new point of contact w1th the land, the thud hiO'hest beach and so on down to the platform nearest to th~ present se'a-beach. Phenomena of this kind b~come comparatively familiar to us, when ~e hear of evidence that the last sixty feet of the ~l~vatwn of Sweden,. and the la:-~t eighty-five of that of C~1h, have taken place s1~ce man first dwelt in those countnes; nay, that the elevatwn of the fonner country goes on at this time at the rate of about forty-five inches in a c.entury, and th~t a thou~and miles of the Chili an coast rose four feet In one night, under the influence of a powerful earthquake, so lately as 1822. Subterranean forces, of the kind then exemplified in Chili, supply a ready explan~tion of the whole phenomena, though some other ope_rahn~ c~uses have been suggested. In an inquiry on th1s pmnt 1t becomes of consequence to learn some partic_ul~rs respecting the levels. Taking a particular beach, It Is general~y ob3erved that the level continues the same along a consHlerable number of miles, and nothing like breaks or hitches ~as as yet been detected in any case. A second and a thud beach are also observed to be ·exactly parallel to the first. These facts would seem to indicate quiet elevating movements, uniform over a large tract. It must, however, be remarked that the raised beaches at one part of a coast rarely coincide with those at · an~ther .P;u~t forty ~r ?f~y miles off. We might suppose th1s to Ind:cate a limit In that extent of the uniformity of the elevating cause, but it would be rash to conclude positively that such is t~e case. In the present sea, as is well. known, there ar~ dtfferent levels at different places, owing to the. operatwn of peculiar local ?ause~, as currents, evapora~wn, .and the Influx of larO'e r1vers 1nto narrow mouthed estuanes. The differences ~f level in the ancient beaches might be occasioned by some such causes. But, what ever dou?t may rest on this minor point. enough _has been as~erta1n_ed to '3ettle the main one that we have In these platforms Indubitable monuments' of the last rise of the land from the sea, and the concluding great event of the geplogical his-tory. . · I The idea of such a wide-spread and poss1~ly un~versa subrnersion unavoiJably suggests some consid~rahor;ts a~ to the effect which it might have upon terrestnal animal life. It seems li.kely that this would be, o~ such an occa- COM.l\IENCEMENT OF PRESEN'r SPECIES. 75 zion, extensively, if not universally, destroyed. Nor does the idea of its universal destructio~ seem the less plausiblP:• when we ~·ema~k, that none of the species of land anunals heretofore dLscovered can be detected at a subse· quent period. The whole seem to have been now changed. Some geolo6ists appear much inclined to think that there ~as at this time a new development of terrestrial animal hfe upon the globe, and M. Agassiz, whose opinion on such a subject must always be worthy of attention speaks all but decidedly for such a conclusion. It mu;t, however, he owned, that proofs for it are still scanty, beyond the bare _fact of a submersion which appears to have had a very w1de range. I must therefore be content to leave this point, as far as geological evidence is concerned, for future affirmation. There are some other superficial deposits, of less consequence on the present occasion than the diluviumnamely, lacustrine deposits, or filled-up lakes; alluvium, or the deposits of rivers beside their n1argins · deltas the d epos1. ts rna d e by great ones at their efflux int' o ·the 's ea; peat mosses; and the vegetable soil. The animal remains found in t~ese g~nerapy testify t~ a z?ology on the verge of that which stlll ex1sts, or melting Into It, there being included many species which still exist. In a lacustrine deposit at Market-Weigh ton, in the vale of York, there have been found bones of the elephant, rhinoceEos, bison ; wolf, horse, felis, deer, birds, all or nearly all extinct species ; associated with thirteen species of land and fresh ~ater s~e~l~, '' exactl~ i~entical ~ith. types now living In the VIClntty." In similar depos1ts In North America, are remains of the rnammoth, mastodon, buffalo, and other animals of extinct and living types. In short, these superficial deposits show precisely such remains as mi~ht be expected from a time at ·which the present systern of things (to use a vague but not unexpressive phrase) obtained, but yet so far remote in chronology as to allow ot the dropping of many species, through familiar causes, in the interval. Still, however, there is no authentic or satisfactory instance of human re1nains being found, except in deposits obviously of very modern date ; a tolerably strong proof that the r.reation of our own species is a cornpiu- ativcly recent event, and one posterior (generally speaking) to all th~ great natural transactions chronicled by geology. |