President's Address. 15 
nodules of manganese and occasionally cosmical dust. Then, 
in water of somewhat less depth we find “Radiolarian Oozes,” 
composed principally of the flinty cases of Radiolarians, and 
remarkably free from calcareous matter. Again, in depths 
still less profound, we meet with the well-known Foramini- 
feral Mud, known to all under the name of “ Globigerina 
Ooze.” 
These are the three most characteristic deposits of the 
deep waters of our present oceans, and while not prepared 
to admit that the deep-water deposits of past geological ages 
must necessarily have been always of the same character, I 
am willing to take that assumption as the basis of argument, 
and I shall endeavour to show that we have in the existing 
dry lands deposits in all essential respects similar to these 
in structure and character, and, therefore, clearly similar 
in their origin. 
There is, however, one consideration which it is most 
important to bear in mind as preliminary to an impartial 
approach to this problem. The consideration to which I 
allude is that true deep-sea deposits must, from the nature 
of the case, be formed with exceeding slowness, and that, as 
a rule, they are not likely to attain a very great thickness. 
As a proof of the extraordinary slowness with which deep- 
sea deposits are often accumulated, we may take the well- 
known fact that the “red clays” of the abysses of our modern 
oceans are often charged with the teeth of Tertiary Sharks 
(Carcharodon). As the dredge, at most, but sweeps up a few 
inches of the mud over which it moves, we must conclude 
that the total thickness of the deposits laid down, in the 
areas examined, in these great depths from the earlier part of 
Tertiary time to the present day can hardly exceed a few 
feet, and in later Tertiary time not more than a foot. Hence, 
under no circumstances, could deep-sea deposits form more 
than a quite insignificant element of the earth’s crust, 
as regards extent and thickness, in comparison with the 
deposits of shallow water. For the same reason, a few 
inches of a deep-water deposit might correspond chronologic- 
ally with many thousands of feet of coarse mechanical 
shallow-water accumulations in some other region. More- 
