estimated that the average area of the North American continent
over geologic time was about eight-tenths of its existing
area.[2] Restorations of other continents, so far as they have
been attempted, would not

[1] On the strength of the Mississippi measurements about 1 to 18
(Magee, _Am. Jour. of Sc._, 1892, p. 188).

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

16

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