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Show 1-1:8 ISLAND LIFE. (l'AR'J' I. - - ---- 1 ft . the valleys · several succes-l ·ues were e In ' glaciation w 1en moral d 1 tion the later ones becom- . d f b gence an e eva , sive peno s 0 su mer . a· ted by the raised beaches d l . ount as m wa ing less an ess m am ' nt coast line ; and lastly, tho slightly elevated above our p:tese f animal remains indicating . th arne deposl s o occurrence 1n e s . t d especially the existence l . d a cold cluna e, an . bot 1 a waun an . y k hire soon after the pen od of of the hippopotamus m or s extreme glaciation. . d f some alternations of climate But although the edvl ence ~O'estion of any adequate cause . d' putn.ble an no suoo . . seems m IS L ' lt t" DO' phases of precessiOn dunng for them other than th~ a erna ~e 0 it by no means follows that high excentrici,ty hasl een may g;eat-that is to say, that the h h es were a ways ver c t ese c ang . d and a warm climate prevailed ice completely dhlsalppeare. It is quite evident that duriug th bout the w o e yeai. . . f roug 1 . 1 poch there was a combmat10n o th heiCYht of the g aCla e . . e 0 s at work w h'lC h 1e d., to a }aroo· e portwn of Nort h-westem cause d E tern America being buried in ice to a greater Europe an as · · 1 t d d xtent even t h an G reenl and is now , since It cm·tam y ex en e be eyond the 1a n d and filled up all the shallow seas between our 1. slan d s an d S can dinavia. Amon(n)' these causes w· e bm u· st reckon a dI. m.m u t'I On of the force of the Gulf Stream' odr Itsh emg diverted from the north-western coasts of ~urope ; an w at we have to consl' de r l.S , whether the alteratwn'l dfr om. a londg lc old a w.m ter and sh or t hot summer , to a short ml wmter. an 'f oano l surumer would greatly affect the amount of ICC ~ Le cooceoa n cuTrents 1'emat.n e d. the same. The force of these c. urrents are I. t I.S true, b y our hypothesis , modifi ed by thel mcrte a1s e 'a. . t' f the ice in the two hemispheres a terna e y, or Immu wn o h t b thus d they then react upon climate; but t ey canno . e aln 0' d till after the ice-accumulation has been c~nsidera.bly c 1anoe . . deecl be affected by other causes. Their drrectwn ~ay, m ' reatly changed by slight alterations in the outlme of the l~nd, !hile they may be barred out altogether by other alteratw:; Of not very great amount; but such changes as these h 1 ave . relation to the alteration of ch· mates cause d b Y the c 1anoo'l lloa Phases of precession. · 1 1 Now, the existence at the Present time of an ICe-c ac CHAP. YIII.] 'l'ITE CAUSES OF GLACIAL EPOCHS. 149 Greenland is an anomaly in the northern hemisphere, only to be explained by the fact that cold currents from the polar area flow down both sides of it. In Eastern Asia we have the lofty Stanivoi Mountains in the same latitude as the southern part of Greenland, which, though their summits are covered with perpetual snow, give rise to no ice-sh eet, and, apparently, even to no important glaciers ;-a fact undoubtedly connected with the warm Japan current flowing partially into the Sea of Okhotsk. So in North-west America we have the lofty coast range, culminating in Mt. St. Elias, nearly 15,000 feet high, and an extensive tract of high land to the north and north-west, with glaciers comparable in size with those of New Zealand, although situated in Lat. 60° instead of in Lat. 45°. Here, too, we have the main body of the Japan current turning east and south, and t.hus producing a mild climate, little inferior to that of Norway, warmed by the Gulf Stream. We thus have it made clear that could the two Arctic currents be diverted from Greenland, that country would become free from ice, and might even be completely forest-clad and inhabitable; while, if the Japan current were to be diverted from the coast of North America and a cold current come out of Behring's Strait, the entire north-western extremity of America would even now become buried in ice. Now it is the opinion of the best Americ~n geologists tha.t during the height of the glacial epoch North-eastern America was considerably elevated.1 This elevation would bring the wide area of the banks of Newfoundland far above water, causing the American coast to stretch out in an immense curve to a point more than 600 miles east of Halifax ; and this would certainly divert much of the greatly reduced Gulf Stream straight across to the coast of Spain. The consequence of such a state of things would probably be that the southward flowing Arctic currents would be much reduced in velocity; and the enormous quantity of icebergs continually produced by the ice-sheets of all the lands bordering the North Atlantic would hang about their shores and the adjacent seas, filling them with a dense ice-pack, far surpassing that of the Antarctic regjons, and chilling the atmosphere so as to produce constant clouds and fog with 1 Dana'~ M11nnul of Grology, 2nd Edition, p. 54.0. |
