DRIFT DIVISION. 
219 
It has already been remarked, that there are no known evidences that there has at any time 
been more water upon the surface of the earth than at present. It follows from the various 
facts known, that the relative levels of land and water have changed, and consequently the 
land must have been elevated, or the bed of the ocean sunk, or both effects more or less ex¬ 
tensively produced. 
The only causes to which we can ascribe such relative changes of level, that have not been 
considered, are, 1, Some force acting beneath or within the crust of the globe, that tends or 
has tended to elevate some parts ; 2, The collapsing of the crust of the globe upon its con¬ 
tracted nucleus irregularly, producing elevation in some parts, and depression in others. The 
powerful lateral thrust in such a case would be amply sufficient to elevate mountains, moun¬ 
tain ranges or continents, and produce all the phenomena of contortion, wrinkling and folding 
of the strata. The phenomena of earthquakes and volcanoes would also flow from the same 
cause, and afford a plausible and perhaps true explanation. 
That one or both of these causes have operated in times past, and will continue for time 
to come, can scarcely be doubted. The phenomena from one of these causes, necessarily 
follow from the refrigeration of the globe, a point concerning which there can be no doubt. 
From the other cause, phenomena similar in character may probably result; but we know of 
no cause that could produce such effects, except the fractured surface allowing water to pene¬ 
trate to the heated interior, to generate steam sufficient in tension and quantity to effect the 
results ; and we know not how the crust could be fractured, except by contraction, and col¬ 
lapse upon the contracted nucleus. 
That the same portions of the crust of the globe have been successively elevated and de¬ 
pressed, is beyond all doubt, from the facts observed by geologists, and numerous local facts 
of this kind have occurred within the historical period; but the geological evidence of similar 
facts on a vast scale, is as strong as if it had come under the direct observation of man. That 
elevation of one part was accompanied by depression in others, is probable ; but the evidences 
of depression are not so easily obtained, as we must look in the sea and on coasts for them. 
“From Mr. Hopkins’s researches, it appears that the elevatory agency was of the nature of 
a gradually augmenting force, very extensive compared to the areas simultaneously disturbed. 
No example of modern earthquakes can be brought to render it probable that mere volcanic 
agency could upraise the continents which it is capable of shaking. Yet as far as we see, a 
more powerful exertion of the same kind of agency might perform the effects; the principle 
of this, and every other explanation, being the necessity of a new adjustment of the exterior 
form and dimensions of the globe in consequence of accumulating tension upon it. 
“ But if, for a moment, we abstract our attention from these limited developments of the 
energies of heat, and consider the elevatory action below continents and islands as the local 
resultant of diffused subterranean forces, it appears possible to arrive at a general and more 
applicable theory. If, as observations seem to indicate, the ocean once covered all or a large 
part of the globe, its mean depth must have been less than at present. Since the inequalities 
of the land arise from subterranean convulsions, and the bed of the sea is very irregular, we may 
admit that the whole, or nearly the whole of the terraqueous area, has been affected by local 
