222 The American Geologist. ^i""- i^o^ 
duccd by projections from the coast; with a general depth 
of less than loo metres. In the vicinity of Bering strait, 
Nansen gives three sections of the continental shelf, two 
of which after showing a breadth of nearly 400 miles begin 
to descend abruptly as if their border were approached. 
Even the fragmentary evidence on the American, side indi- 
cated that the edge of the shelf (reduced to a width of 70 
kilomtres) is at the same depth of about 100 metres as else- 
where. Franz Josepf land and Spitzbergen are located on 
the outer edge of the shelf which is here somewhat broader. 
The depth is irregular, showing that the platform is dis- 
sected by valleys communicating with the Polar basin at 
one end, and the Norwegian sea at the other. This is on 
the floor of Barentz sea, which extends from these islands 
to Novaya Zemlia and the Norwegian coast. The irregu- 
larity of the soundings in this sea may in part be attributed 
to the partial filling of the ancient valleys by glacial depos- 
its, river silts, the drifted sediments of coast-wise wash 
and the levelling effect of the floating ice on the bottom of 
the shallow sea, but the valleys themselves are more or 
less apparent. These are described in considerable detail, 
along with their tributary branches, as well as those of 
Kara sea. The valley-like features are traced to the edge 
of the submarine plain, but the soundings in them have not 
generally reached to more than 400-500 metres. (Still the 
reviewer had observed a cove to 8,100 feet incising the con- 
tinental slope southwest of Spitzbergen, where the depth 
below the sea level is only 840 feet. This indicates that 
the valleys extend to the floor of the basin.) The rapid 
descent from the shelf is shown in various places. Some 
idea of this last feature may be obtained north of Spitz- 
bergen, where in a distance of about 30 miles, a slope from 
171 metres to 1,150 occurs. In his great discovery of the 
deep Arctic basin, Nansen found the slope north of the New 
Siberian islands reached from 100 metres on the edge ol the 
shelf to over 1,920 in a distance of 40 miles. 
Off the Siberian coast, he did not find the valleys on 
the surface of the shelf, which fact he attributes to their 
refilling by the coast-wise distribution of the sediments 
brought down by the great rivers. But he observed many 
