532 T. C. CHAMBERLIN 
of accumulating strains of high value, the case is very different, for 
in such case the crust movements are not immediately responsive to 
loading and unloading. These can induce only a slight elastic 
strain in the elastic body. No nice adjustment to deposit can be 
assumed in this case. In my judgment the phenomena of geology 
and related sciences support this view and are distinctly opposed 
to a concurrent adjustment to loading and unloading of the degree 
of nicety required for the assigned work. 
A close adjustment in response to loading and unloading seems 
on first thought to be supported by views of isostasy that have 
recently been put forth on the basis of elaborate studies of geodetic 
data,’ but this seems to me an untenable application of deductions 
very Important in their true implications, for such a degree of 
pliancy seems entirely inconsistent with the maintenance of the 
continents even on the basis of complete vertical isostasy, as will 
appear from considerations offered in a subsequent discussion, for 
any type of ‘sostasy that is consistent with the existence of the con- 
tinents and oceanic basins, as they are, involves great lateral unbal- 
anced stresses. 
The protuberance of the continents and their repeated rejuve- 
nations when worn down can be explained, it would seem, only on 
the supposition that the mean specific gravity of the continents is 
lighter than that of the sub-oceanic segments. ‘This is the postulate 
of isostasy. Pendulum observations confirm it. It is common 
ground where diverse views meet. 
Now the continents are always being denuded by the mechanical 
action of wind, water, and gravity on the surface, and by the solvent 
action of water reaching to notable depths. The protuberances are 
not only being cut away, but are being leached all the time. There 
is no real weighting of the continent as a whole under normal con- 
ditions. The only apparent weighting is due to that fraction of the 
sediments that lodges somewhere on it in its course to the great 
deeps. This fraction is gathered chiefly about the edges of the 
continent and the weighting there is only a fraction of the unloading 
of the continent as a whole. The continent as such is being con- 
stantly lightened, and if it was in previous equilibrium its constant 
' Hayford, loc. cit. 
