TL. M. Reade—Denudation of the two Americas. 299 
quite sufficient to account for much of the argillaceous matter 
found in the deep ocean soundings. ave shown that the 
matters in solution in rain waters are, roughly speaking, one 
quarter of the whole matter in the water in solution and sus- 
pension. The finest particles, sufficiently fine to be carried 
away by oceanic surface currents, such as the Gulf Stream, are 
probably not in bulk half as great as the matter in solution. 
If we take as an example the estimate I have given of the 
chemical denudation of England an ales it amounts, as I 
have already shown, to 34, of an inch in 80 years, This would 
give, supposing the impalpable mud to be worn off at half that 
rate, 60 years for the denudation of 3, of an inch. The area of 
the sea to land is roughly as 8 to 1, therefore at this rate it 
would take 180 years for }, of an inch of mud converted into 
rock to accumulate if distributed evenly over the ocean floor. 
When we consider the average depth of the ocean is over two 
miles, 31, of an inch distributed through it would amount to no 
more than about one five-millionth part, and this, be it remem- 
bered, has 180 years to accumulate and settle, so that if we give 
each particle of these fine matters in suspension 10 years to 
settle to the bottom there would never be in the ocean water at 
One time more than one ninety-millionth part of matters in sus- 
pension, an amount so small as to be practically imperceptible. 
The probability that such an infinitesimal amount of matter in 
suspension may be present is still more evident when we find 
that fine sand floats on the surface of the sea for considerable 
distances, for Prof. Verrill says that in the course of the Gulf 
Stream they always take with their towing nets more or less 
fine siliceous sand* (this Journ., 1882, xxiv, p. ‘ 
think it is fairly evident from the foregoing calculations 
* Prof. A. E. Verrill alsosays that, in the Gulf Stream slope examined by us. 
the bottom in 70 to 300 fathoms, 60 to 120 miles from the shore, is composed 
remarkable absence of actual mud or clay deposits indicate that there is here a 
the bottom sufficient current to prevent for the most part the deposition of fine 
argillaceous sediments over the upper portion of the slope in 65 to 150 fathoms. 
