156 The American Geologist 
March, 1905 
pliocene period, which was one of great terrestrial changes 
of land and sea over Europe. The fashioning of the conti- 
nental declivity or slope, with its channels belongs to the 
Pleistocene period. 
\\'hile a change of level raising the sea bottom 9000 
feet and sinking it again may cause some hesitation in our 
minds, yet the marine Tertiary beds occur to 10,000 feet in 
the Alps, which have received their features in post- 
Miocene times, according to Heins, Renevier, Baltzer, Carl 
Schmidt, and H. Schardt. The sea level may have been 
considerably lowered b}' the accumulation of ice in the 
Glacial period, or again the beds of the great oceans may 
have been depressed, as suggested by Prof. Suess.* Also 
there may have been other ways, more or less speculative 
altering the level of the sea as described by Prof. James 
Geikie. In conclusion. Hull finds the continental slope to 
great depths "charcterized by physical features similar to 
those we observe on the land and due largely to similar 
causes, namely, marine and atmospheric erosion." Of 
Prof. Hull's paper Prof. Ethridge says : "Prof. Hull's in- 
terpretation that the submerged and now submarine valleys 
were originally formed or fashioned through atmospheric 
denudation in the widest sense, prior to their submergence 
is fully demonstrated." "Xo one has hitherto applied these 
ocean soundings for the purpose of elucidating the past 
physical history of the old and new submerged land once 
extending far to the west or into the now depths of the At- 
lantic." Prof. T. Rupert Jones endorses the author and 
says : ''Dr. E. Hull, applying the methods adopted Sy Dr. 
Spencer and other American observers, is led by careful 
consideration of the Admiralty charts, and with accurate 
reasoning on the relative depths of the water, to map out 
the margins of the British area before it became divided up 
into the existing islands. The conclusions add much to 
our knowledge of geographical evolution, as brought about 
by natural causes during immense periods of time." The 
lOO-fathom line had been the chief datum of former work- 
ers. "The distribution of animals and plants supports the 
conclusions arrived at by Prof. Hull" that the recent high 
* T.OC. cit., p. 639. 
