THE SUB-GLACIAL STREAM. 41 



at the time the bottom layers or strata of this laminated clay were 

 formed, there was no life in the Arctic waters, or that they were 

 formed under circumstances which prevented their being fossili- 

 ferous. The bearing of this on the subject in question need scarcely 

 be pointed out. It ought to be noted that, supposing 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 ends ; and certain other places on the 

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

 Davis Straits and Baffin 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 we 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 

 different 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. 1 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. Kink 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. 



1 It may be somewhat superfluous for me to say that these subglacial streams 

 arc totally different in nature from the streams which flowed in the old water- 

 courses found under the drift in various parts of the world. These were the beds 

 of the preglacial rivers, and are known to miners as " sand-dykes,'' " washouts," 

 &c. On the North Pacific slope of the fiocky Mountains they are very common, 

 and are eagerly sought for by the gold-miners, the "old beds" generally yielding 

 a considerable amount of gold. In California, so thoroughly have they been 

 explored by the gold-diggers that, if proper records had been kept, a map "I the 

 preglacial rivers might now be drawn, almost as detailed a.s that of the postglacial 

 ■or present river-system. The courses of these ancient rivers appear to have been 

 generally in the same direction, and to have had their outlets in the valleys near 

 about the same places as the present rivers. Sometimes these channels Beem to 

 cross nearly at right angles. The old Yuba channel, for instance, when its course 

 was interrupted and diverted, ran through the site of the present village of 

 " Timbuctoo," crossingthe bed of the present river at Park's Bar; thence running 



in a north-westerly course, and falling into the Kio de las Plumas (Feather 



Biver), Dear OrovlUe, a considerable distance from its present junction with that 

 river at Marysville. These old channels exhibit the same windings and pre- 

 cipitous falls as the present river ; and they have been cul in various places bv 

 canons and ravines; and portions of the older deposit, carried down, mingle with 



the loose gravel and sand detached by more recent aqueous action. 



