104 'l^Ji'<^ American Geologist. August, i898 
powerful glacial erosion along their courses, such as may be 
supposed to have greatly deepened some of the fjords. 
One of the most interesting of the preglacial river valleys 
now submerged extends thirty miles out in a nearly straight 
west-northwest course, from the mouth of the Sule fjord, 
which is the seaward continuation, between islands, of the Stor 
fjord. This is a well defined channel in the sea bed, having 
a width of one and a half to two miles. Its depth is mostly 
850 to 1,000 feet, with depths of only 200 feet, or less, to 500 
feet, on each side. It is called, on the chart, Bredsundsdybet 
(the "Depth in the Broad sound"). Before reaching the edge 
of the submarine continental slope, this channel gradually 
shoals out within five miles and is lost, the depth of the sea 
there being only about 300 feet. From the central part of its 
course, however, a wider submarine channel of 500 to 885 feet 
depth, runs southward and thence westward to the deeper sea, 
indicating the probable course by which the preglacial valleys 
of the Nord and Stor fjords discharged their united waters. 
Besides the preglacial stream and sea deposits which 
niainly built up the coastal plain, it is certain that much glacial 
drift is spread over it, everywhere partially filling the old 
river courses and probably in many places covering them en- 
tirely. The drift deposition appears to have been deepest, 
however, just along or close outside the present shore, in the 
meandering channels of the coastal belt of islands, and at the 
mouths of the fjords, which always attain their greatest depth 
at some distance inland. Although some of the fjords ex- 
ceed 2,000 feet in depth, and one is 4,080 feet deep, the mouths 
of them all are comparatively shallow, being usually from 100 
to 300 or 500 feet deep. Whether we ascribe the excavation of 
the deeper fjords chiefly to preglacial streams or chiefly (in 
its latest and deepest part) to glacial erosion, we shall in either 
case be led to the conclusion that their mouths and the ad- 
joining sea must be much Imilt up with glacial deposits. 
The British Isles, as shown by the studies of Prof. James 
Geikie, Prof. Edward Hull, and others, stand on a broad, shal- 
lowly submerged continental platform, which is terminated 
westward, at the submarine contours of 100 to 200 fathoms 
(600 to 1,200 feet), by steeply descending slopes to the abyssal 
ocean. Narrow vallevs from 100 to 400 feet deep below the con- 
