220 The American Geologist. ^i"''- '^^^ 
waters, thus affecting the warm currents and the distribu- 
tion of life. 
A conspicuous feature of the Polar basin is the small 
amount of Foraminifera and of carbonate of lime, in one 
case five per cent, in others from one to three per cent. 
This scarcity may be attributed to the absorption of light 
by the ice. The deep sea brown clay, which prevails on the 
bottom of the I'olar basin, is very much like the Biloculina 
clay which occurs in the Norwegian sea (this organism 
does not occur here), but the percentage of lime is very 
much less. These organic deposits indicate former more 
favorable i^iblogical conditions. Very little terrigenous 
matter reaches the deep basin from the rivers, and the fine- 
ness of the deposits there compared with the coarse mate- 
rial of the coast region, shows that there has been no great 
glacial drift across the Polar basin. Xansen very rarely 
found any stones, as large as a pea, on the floe-ice, but in 
many cases, dust and mud were seen in quantities. In a 
very cold sea even the shore ice travels across it without 
depositing its load, and in this case it finally melts east of 
Greenland, where the debris sinks to the sea floor. 
The continental shelf of Barentz sea becomes con- 
tracted to about 50 kilometres off the Norwegian coast in 
front of the neighboring high mountains from Tromso to 
Vesteraalm. but beyond it widens out, supporting the Lo- 
foden islands, and reaches the breadth of 250 kilometres 
in the vicinity of latitude 66°. The edge of the shelf then 
turns landward so that it recedes to within 80 kilometres 
of the coast in front of Aalesund. Farther on^ it turns 
westward, and the continental shelf itself is represented by 
the floor of the North sea, near latitude 62°. This defini- 
tion requires further explanation, for from this point south- 
ward and around to Christiania fjord is the merest fringe 
of the continental shelf, which might be said to disappear, 
if it were not repeated on the other side of the broad sub- 
ms.rine Norwegian channel, as the floor of the North sea; 
accordingly the great shelf itself is only incised by the 
channel, which is a minor feature. This Norwegian chan- 
nel extends inward for 480 nautical miles, with a breadth 
of 40-56 miles, to Christiania fjord, having the Sogne fjord 
