220 
GEOLOGY OF THE FIRST DISTRICT. 
displacements. It is the resistance offered hy the consolidated crust of the globe to a gra¬ 
dually augmenting change of internal dimensions, which caused the disturbing movements. 
We may therefore allow, that before the production of a consolidated crust of the globe, the 
ocean (if it existed in a liquid form) was spread with considerable uniformity over the spherical 
surface. 
“ From these postulates, it must follow that the actual bed of the sea has been formed by 
displacements, which upon the whole have caused a real subsidence ; as the displacements 
of the land have, upon the whole, caused a real elevation of it. And our confidence in the 
assumed condition is augmented by observing, first, that they are all implied in the inferences 
from phenomena already adopted, and that they agree with the sentiments of astronomers as 
to the relative depths of the sea to the heights of the land. 
“ In endeavoring to embrace the phenomena of elevation and subsidence in one point of 
view, it appears almost immaterial whether we suppose the tension of the consolidated crust of 
the globe, which preceded its fracture and displacement, to have arisen from inward or outward 
pressure—from expansion of, or contraction upon the interior nucleus ; because, in each case, 
the pressure would be of the general and gradually accumulating description required : but it 
seems an unavoidable condition, that the interior nucleus should be of a yielding nature, to 
permit the subsidence of large portions of the surface, and accommodate itself permanently 
to the elevations. This condition leads us to the supposition of great interior heat, which, 
from general physical considerations, had before appeared very probable, and, from experi¬ 
mental researches, almost a matter of certainty.* 
“ If then we regard this heat as variable, (and, placed as the hot globe is in the vast cold 
regions of space,! through which it radiates its uncompensated rays, it must be so—the globe 
must be growing cooler,) and we have at once the general physical cause of the phenomena 
of disruption and displacement on the crust of the globe, viz. a collapse of this crust 
UPON THE INTERNAL NUCLEUS SLOWLY CONTRACTED BY REFRIGERATION.”^ 
This must have occurred either at intervals by paroxysms, when the action of gravitation 
became too powerful for the resisting force to withstand, causing subsidences in some parts, 
elevations, contortion and wrinkling of the strata in others; or in a more uniform subsidence 
upon the contracted nucleus, producing the same effects, but in a slow, and perhaps to human 
observation almost insensible manner. The diminished diameter would necessarily change 
the length of our day, rendering it shorter; but the observations and calculations of astrono- 
* Perhaps these, with the evidences of polar currents heightened in their effects at particular epochs, may be considered as 
giving it all the certainity that is attainable with our present knowledge of the earth. 
t Three different modes of calculating the temperature of space, gave the following results: 
Fourier, = —50®. 00 centigrade. 
Svanberg, = —49°. 85 “ 
Ditto, = — 50°.35 “ Prom Lambert’s statements on the absorption that takes 
place in a ray of light passing from the zenith through the atmosphere. Vide De la Beche’s Manual (Phil. 1832, p. 24); 
Edinburgh Journal of Science, Vol. 3, New series, 
t Phillifs. Treatise on Geology. Edinburgh, 1838, pp. 281, 283. 
