Nansens Continental Oscillations — Spencer. 227 
and other tributaries. It is so close to the shore that 
the higher portion of the continental shelf does not appear. 
This channel ends abruptly in three tributary fjords. 
The soundings of the continental shelf display many 
irregularities, on account of the incisions in it. The great 
valley fjords cross it. These are obstructed by barriers 
near the outer coast line. The shelf is naturally best de- 
veloped between the valleys, and the broadest and deepest 
shelves or platforms are situated in front of the lowest 
coast, and the highest and narrowest in front of precipitous 
coasts. The author distinguishes a coast platform from 
the general shelf. This is where the shallow sea is studded 
with low islands and skerries. It has an important bear- 
ing on the question of the origin of the shelves considered 
later. The local descriptions with sections are given in 
great detail, and these are necessary to understand the 
general characteristics. 
The Norwegian shelf, almost everywhere, terminates 
abruptly, and its very level or gently undulating surface is 
in contrast with the rapid descent of the continental slope 
extending to oceanic depths. On this the gradients are 
steepest between 200 and 1,000 metres, becoming gentler 
from 1,500 to 2,000 metres. Even down the §lope, evi- 
dences of river-like valleys may be traced to the greatest 
depths where soundings have been made. North of Ando 
they have thus been found to over 1,000 mteres, within the 
edge of the shelf itself, which here has a depth from less 
than 100 metres to 400 according as it is the upper or lower 
platform. Many undulations in the isobaths of the slope 
indicate channels to 800 metres. 
From Barentz sea to latitude 67° the upper levels of the 
• continental shelf usually reach to its very edge ; as also be- 
yond latitude 6-1.°. Between these points, the main shelf is 
indented oy an embayment, which is floored by a lower 
plain, whose outer edge is bounded by the 400-metre line. 
This lower submarine plateau reappears in the Norwegian 
channel, and far north in Barentz sea. 
Sometimes the valleys appearing on the continental 
slope lie outside of the line of the modern channels. This 
is attributed to a diversion from the older ones apparent 
