[2] Schuchert, Bull.  Geol.  Soc.  Am., vol. xx., 1910.

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suggest any more serious divergency one way or the other.

That climate in the oceans and upon the land was throughout much as it is now, the continuous chain of teeming life and the sensitive temperature limits of protoplasmic existence are sufficient evidence.[1] The influence at once of climate and of elevation of the land may be appraised at their true value by the ascertained facts of solvent denudation, as the following table shows.

Tonnes removed in Mean elevation.
solution per square Metres.
mile per annum. 
North America — 79 700
South America — 50 650
Europe — 100 300
Asia — 84 950
Africa — 44 650

In this table the estimated number of tonnes of matter in solution, which for every square mile of area the rivers convey to the ocean in one year, is given in the first column.  These results are compiled by Clarke from a very large number of analyses of river waters.  The second column of the table gives the mean heights in metres above sea level of the several continents, as cited by Arrhenius.[2]

Of all the denudation results given in the table, those relating to North America and to Europe are far the

[1] See also Poulton, Address to Sect.  D., Brit.  Assoc.  Rep., 1896.

[2] Lehybuch dev Kosmischen Physik, vol. i., p. 347.

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most reliable.  Indeed these may be described as highly reliable, being founded on some thousands of analyses, many of which have been systematically pursued through every season of the year.  These show that Europe with a mean altitude of less than half that of North America sheds to the ocean 25 per cent. more salts.  A result which is to be expected when the more important factors of solvent denudation are given intelligent consideration and we discriminate between conditions favouring solvent and detrital denudation respectively:  conditions in many cases antagonistic.[1] Hence if it is true, as has been stated, that we now live in a period of exceptionally high continental elevation, we must infer that the average supply of salts to the ocean by the rivers of the world is less than over the long past, and that, therefore, our estimate of the age of the Earth as already given is excessive.

There is, however, one condition which will operate to unduly diminish our estimate of geologic time, and it is a condition which may possibly obtain at the present time.  If the land is, on the whole, now sinking relatively to the ocean level, the denudation area tends, as we have seen, to move inwards.  It will thus encroach upon regions which have not for long periods drained to the ocean.  On such areas there is an accumulation of soluble salts which the deficient rivers have not been able to carry to the ocean.  Thus the salt content of certain of