io6 TJie American Geologist Angnst, i898 
had cut down about 750 feet. Twenty-five miles from the 
Cap Breton shore, the valley has the profound depth of 3,670 
feet, and has widened to about ten miles between the tops of 
its sides, which, like the general sea bed of large expanses 
north and south, have the depth of about 460 feet. At forty 
miles the valley has a sounding of 6,135 feet. At eighty miles 
its depth is 7,140 feet. Within seven miles farther it more 
rapidly deepens to 8,700 feet, with 650 and 1,175 f^^t less 
depth two miles away respectively on its south and north 
sides. Thence along a distance of thirty miles it holds a 
somewhat uniform depth from 8,700 to 9,000 feet, this being 
apparently the measure of the maxinumi continental uplift 
when the old river eroded its valley. Thirty miles northward 
from where the valley ceases to be recognizable, the Bay of 
Biscay is 10,830 feet deep, and twenty miles farther north its 
depth is 12,600 feet. 
The present representative of the old river is the Adour, 
which has its mouth ten miles south of the "Fosse de Cap 
Breton;" but formerly it was turned northward by dunes, so 
that its mouth at the end of the fourteenth century is said to 
have been about ten miles north of Cap Breton. 
This submerged Adour valley is the most accurately 
known, by special hydrographic surveys, among several others 
on the border of the continental plateau in the Bay of Biscay 
and along the western coast of Spain and Portugal, which 
together demonstrate for southwestern Europe an uplift of 
late geological date to a vertical amount ranging- probably 
from 5,000 to 9,000 feet. The border of the continent, built 
out by sedimentation during the Tertiary era to the submarine 
contours of 600 to 1,200 feet, with steep descent thence into 
the deep ocean, has mainly on these coasts a width of 10 to 30 
01 40 miles. Subsequent to the formation of this continental 
shelf bordering the hilly and mountainous present land area, 
western Europe and western Africa experienced an epeirogenic 
uplift which at its maximum, as known by the submerged 
Adour and Congo valleys, lifted these great land areas from 
one mile to nearly two miles vertically above their present 
altitude.* 
*From the mouth of the river Congo its submerged valley is traced 
by J. Y. Buchanan to a distance of about 100 miles and a depth ex- 
ceeding 6,000 feet; and another submarine valley of great depth, called 
