24 



POST-TERTIARY ENTOMOSTRACA. 



expresses a strong opinion " regarding the identical cliaracter of the sub-glacial stream- 

 clay, and tlie fossiliferous brick-clay." 



In this clayey bed tlie Arctic Mollnsca and other marine animals find a congenial 

 home, and burrow into it in great numbers. However, as the new deposits are thrown 

 down, they keep near the surface to be able to get their food ; so that if to-day a cata- 

 strophe were to overwhelm the whole marine life of the Arctic regions, it would be found 

 (supposing by upheaval or otherwise we were able to verify the fact) that the animals 

 would only be imbedded in the upper strata of clay, and that the bottom one, with the 

 exception of a few dead shells, would be azoic ; yet I need not say how erroneously we 

 should argue, if, from this, we drew the inference that at the time the bottom layers or 

 strata of this laminated clay were formed there Avas no life in the Arctic waters, and that 

 they were formed under circumstances which prevented their being fossiliferous. The 

 bearing of this on the subject in question nee'd scarcely be pointed out. It ought to be 

 noted that, supposuig we were able to examine the bottom of the Arctic Sea (Davis' 

 Straits, for instance), it would be found that this clayey deposit would not be found over 

 the whole surface of it, but only over patches. For instance, all of the ice-fjords would 

 be found full of it to the depth of many feet, shoaling off at the seaward end ; and certain 

 other places on the coast would be also covered with it ; but the middle and mouth of 

 Davis' Straits and Baffin's Bay, and the wide intervals between the different ice-fjords, 

 would either be bare or but slightly covered with small patches from local glaciers ; yet 

 Ave should reason most grievously in error did we conclude therefrom that the other 

 portions of the bottom covered with sand, gravel, or black mud were laid down at a 

 different period from the other, or under other difi"erent conditions than geographical 

 position. These ice-rivers seem, in the first place, to have taken their direction according 

 to the nature of the country over which the inland ice lies, and latterly according 

 to the course of the glaciers. No doubt they branch over the whole country, like a 

 regular river-system. When the glacier reaches the sea, the stream flows out under the 

 water, and, owing to the smaller specific gravity of the fresh water, rises to the surface, 

 as Dr. Rink describes, ' like springs,' though I do not suppose that he considers (as some 

 have supposed him to do) that that water was in reality spring-water, or of the nature of 

 springs. Here are (jenerully swarms of Entomostraca and other marine animals, which 

 attract flifjhts of gulls, tvhich are ever noisily fighting for their food in the vicinity of such 

 places" (p. 682-4). 



It is very noticeable that the same kind of laminated clay occupies precisely the same 

 position in the series of glacial beds exposed near Christiania.^ 



We observed the followmg section at the Lower Foss Clay Bank, near Christiania. 

 1. Unfossiliferous boulder-clay (with striated blocks, hard and compact). 



1 See 'Notes on the Post-Tertiary Geology of Norway.' By H. W. Crosskey and D. Robertson. 

 'Trans. Phil. Soc. of Glasgow,' 1868. 



