360 



SCIENCE 



[N. S. Vol. XXXII. No. 820 



especially in the quiet depths of submerged 

 valleys. Shore-ice in Arctic regions, as 

 Colonel H. W. Feilden"^ has described, can 

 striate stones and even the rock beneath it, 

 and is able, on a subsiding area, gradually 

 to push boulders up to a higher level. In 

 fact the state of the British region in those 

 ages would not have been unlike that still 

 existing near the coasts of the Barents and 

 Kara Seas. Over the submerged region 

 southward, and in some cases more or less 

 eastward, currents would be prevalent; 

 though changes of wind^" would often af- 

 fect the drift of the floating ice-rafts. But 

 though the submergence hypothesis is obvi- 

 ously free from the serious difficulties which 

 have been indicated in discussing the other 

 one, it gives a simple explanation of the 

 presence of marine organisms, and accords 

 with what can be proved to have occurred 

 in Norway, Weigatz Island, Novaia Zem- 

 lya, on the Lower St. Lawrence, in Grinnell 

 Land and elsewhere,"" it undoubtedly in- 

 volves others. One of them — the absence 

 of shore terraces, caves or other sea marks 

 ■ — is perhaps hardly so grave as it is often 

 thought to be. It may be met by the re- 

 mark that unless the glacial age lasted for 

 a very long time and the movements were 

 interrupted by well-marked pauses, we 

 could not expect to find any such record. 

 In regard also to another objection, the 

 rather rare and sporadic occurrence of 

 marine shells, the answer would be that, on 

 the Norway coast, where the ice-worn rock 

 has certainly been submerged, sea-shells are 

 far from common and occur sporadically 

 in the raised deltaic deposits of the fjords.''^ 



^ Quart. Jo-urn. Geol. Soc, XXXIV., 1878, p. 

 556. 



^° See p. 23, and for the currents now dominant 

 consult Dr. H. Bassett in Professor Herdman's 

 Report oh the Lancashire Sea Fisheries, Trans. 

 Biol. Soc. Liverpool, XXIV., 1910, p. 123. 



"> See " lee Work," p. 221, and Geol. Mag., 1900, 

 p. 289. 



"^ If, as seems probable, the temperature was 



An advocate of this view might also com- 

 plain, not without justice, that, if he cited 

 an inland terrace, it was promptly dis- 

 missed as the product of an ice-dammed 

 lake, and his frequent instances of marine 

 shells in stratified drifts were declared to 

 have been transported from the sea by the 

 lobe of an ice-sheet ; even if they have been 

 carried across the path of the Arenig ice, 

 more than forty miles, as the crow flies, 

 from the Irish Sea up the Valley of the 

 Severn, or forced some 1,300 feet up Moel 

 Tryfaen.**- The difficulty in the latter 

 case, he would observe is not met by saying 

 the ice-sheet would be able to climb that 

 hill "given there were a sufficient head be- 

 hind it.""^ That ice can be driven uphill 

 has long been known, but the existence of 

 the "sufficient head" must be demon- 

 strated, not assumed. There may be "no 

 logical halting-place between an uplift of 

 ten or twenty feet to surmount a roche 

 moutonnee and an equally gradual eleva- 

 tion to the height of Moel Tryfaen," yet 

 there is a common-sense limitation, even to 

 a destructive sorites. The argument, in 

 fact, is more specious than valid, till we are 



changing rather rapidly the old fauna would be 

 pauperized and the new one make its way but 

 slowly into the British fjords. 



"^ Critics of the submergence hypothesis seem to 

 find a difficulty in admitting downward and up- 

 ward movements, amounting sometimes to nearly 

 1,400 feet during Pleistocene ages; but in the 

 northern part of America the upheaval, at any 

 rate, has amounted to about 1,000 feet, while on 

 the western coast, beneath the lofty summit of 

 Mount St. Elias, marine shells of existing species 

 have been obtained some 5,000 feet above sea-level. 

 It is also admitted that in several places the pre- 

 glacial surface of the land was much above its 

 present level. On the Red River, whatever be the 

 explanation, foraminifers, radiolarians and sponge 

 spicules have been found at 700 feet above sea- 

 level, and near Victoria, on the Saskatchewan, 

 even up to about 1,900 feet. 



•"P. F. Kendall in Wright's "Man and the 

 Glacial Period," p. 171. 



