Nr. 6] KVARTÆK-STUDIEK 1 TRONDHJEMSFELTET 215 



har WooDWARD git en god oversigt i sin »Manual of the Mollusca« 

 (London 1910, pag. 54). Woodward anfører her, at Mr. Kirby 



regarded de nævnte provinser as fixed by the ^vill of the 

 Creator, rather than as regulated bj' isotliermal Unes , og at 

 Mr. SvvAiNSON har vist, at circumstances connected with temi)era 

 ture, food, situation, and foes, are totally insufficient to accounl 

 for the phenomena of aninial geography , som han saa tilskriver 



operation of unknown huvs Og Woooward sier, at the most 

 imporlant conlribution towards a knowledge of these unknown 

 laws has been made by Professor E. Forbes«, idet han ogsaa 

 videre tilføier: it may be stated that — — — the Faunas of 

 the Provinces are of various ages, and that their origin is con- 

 nected Nvith former geological changes, and a dilTerent distribution 

 of land and waler over the surface of the globe . Det var den 

 samme tanke, som paa en mere aarsaksmæssig og bestemt maate 

 blev videre utformet af Croll, der uttaler: That a geographical 

 distribution of land and water permitting of the existence and 

 delleclion of those heal bearing currents is one of the main 

 factors in my theory is what must be obvious to every reader 

 of Climale and Time'. The difference between Mr. Wallace 

 and myself is this: — I maintain that with the present distri- 

 bution of land and ^vater, without calling in the aid of any other 

 geographical conditions than now obtain, those physical agencies 

 detailed in Climale and Time' are perfectly sufficient to accounl 

 for all the j)henomena of the Glacial Epoch, including those 



inlercalaled warm periods — while Sir. Wallace, on the 



other hånd, mainlains that Nvilhout assuming some change in 

 the geographical conditions of om- globe those physical agencies 

 will nol accounl for thai slale of Ihings vThe American Journal 

 of Science, Ser. '■), Vol. 27 ^884), pag. 89). Og denne veksling 

 foraarsakel ved klimatiske forandringer møler vi igjen overalt, 

 — fænomenet er del samme, naar George fremhæver, al in 

 each glacier Ihere are Iwo loci of maximum erosion; one at 

 the head of llie glacier — — — Ihc olher benealh the central 

 /one of the glacier ilself some distance upslream from Ihe foot 

 of the glacier ((Canada Geol. Surv. Memoir. Xo. 38, P. II, 1912, 

 pag. 636), og naar vi møler lo og lo af indsøer grupperet i de 

 brieskurede dale eller bolner som el bevis for bræernes eroderende 

 belydiiiiig likeoverfor reliefels ulfornining og del lilliods for, al 

 Daves, som senere har bidral saa nu'gel lil al belyse glacial- 

 eiosioiuMis natur og betydning som reliefdannende faktor, i 1882 

 ganske kategorisk ullallc: No large lakes have been prodiiciul 

 i)y glacial erosion Ihc most considerable topograpliic 



elTect |)r()(liice(l by glacicis isl liic hea|)ing ol" various moraiiial 

 (Icposils OM au arra smaller lliau llicir sourcc Proi" Hosl Soc 



