248 W. O. Croshby—Origin of Continents. 
and others that this red clay is not matched by any rock now ex- 
posed on the continents, although Sir Wyville earlier expressed the 
opinion that a deposit of this red clay might come to be very like 
one of the ferruginous Paleeozoic schists. 
But the point that I wish to raise now is embodied in the following 
question: Are there any deep-sea deposits? If, as I believe, this 
question may be fairly answered in the negative, then the argument 
that these sediments are not represented on the continents ceases to 
have any weight. Now nothing has been more clearly demonstrated 
by the deep-sea explorations of the last fifteen years than that the 
abyssal sediments, and especially the red clay, are accumulating 
very slowly. Over the red clay areas, the dredge brings up large 
numbers of nodules of the iron and manganese per-oxides; and 
Sir Wyville Thomson has shown that we have in these nodules 
and in some of their nuclei “ample evidence that this abyssal 
deposit is taking place with extreme slowness; for the nodules are 
evidently formed in the clay, and the formation of the larger ones 
and the segregation of the material must have required a very long 
time; while many of.the sharks’ teeth forming the nuclei of the 
nodules belong to species which we have every reason to believe 
have been extinct since early Tertiary times. Some teeth of a 
species of Carcharodon are of enormous size, four inches across the 
base, and are indistinguishable from the huge teeth found in the 
Eocene beds.” On this point Mr. John Murray says: “ When there 
has been no reason to suppose that the trawl has sunk more than one 
or two inches in the clay, we have had in the bag over a hundred 
sharks’ teeth, and between thirty and forty ear-bones of whales.” 
The time since the Eocene, when the Carcharodons lived, is 
estimated by geologists at more than a million years, and yet enough 
clay has not been deposited during this immense period to bury the 
teeth of this giant shark beyond the reach of the dredge! the rate 
of increase of the sediments being probably less than one foot, and 
possibly not more than two or three inches, in a million years. 
Now suppose that after a submergence of ten million years the 
floor of the deep ocean is slowly raised to form dry land. Is it 
surprising that a bed five or possibly ten feet thick of ferruginous 
clay, containing organic remains similar to those found in shore 
deposits, is not recognized as of abyssal origin, but is completely 
lost among the miles of marginal sediments composing the new 
continent? In the ordinary sense, there are no abyssal sediments, 
but we find over these oceanic wastes merely the impalpable dust 
which slowly settles during the lapse of countless ages from the 
limpid water of the central sea. The land is the great theatre of 
erosion and the sea of deposition; but just as there are extensive 
rainless tracts on the continents where there is practically no 
erosion, so there exist still larger areas of ocean-floor over which 
the complementary process, or deposition, approaches the vanishing 
point. On both land and sea the main field of geological operations 
is marginal, following the shore-line; but nowhere does the earth’s 
crust experience such perfect rest as under the deep sea. 
