On the Physical Geology of the United States, §c. 285 
The ocean being a fluid, maintains its equilibrium and retains 
its level, and we have no alternative but to admit, that the solid 
ground has been elevated above its former level, and also that 
the surface of the earth has not all the stability that is usually as- 
signed to it. 
These conclusions are conformable to observations during the 
historical epoch, and also to the philosophical deductions from 
known dynamical causes, and from the facts observed among the 
solid strata of the globe.* 
Various causes have been assigned for the elevation of land 
above the level of the sea, beneath which it was once buried, as 
follows, viz. 
Ist. Volcanic agency, by the aid of highly elastic steam and 
gases. 
2d. Unequal contraction of water and land by a diminution of 
the mean temperature of the earth. 
3d. An undulatory action of the fluid interior of the earth, com- 
bined with a lateral tangential force. 
Ath. The contraction of the earth by secular refrigeration, and 
the solid exterior collapsing upon the fluid interior, and being too 
large to embrace it closely, causes plications and bending of the 
strata, depressing some parts below the general level, and eleva- 
ting others by lateral thrust. 
The first of these causes, viz. that of volcanic action, may be 
considered as one of the effects of a more general cause, and to 
which the elevatory movements may also, independently, be as- 
cribed. 
The second, viz. that of unequal contraction of land and water 
by a diminished mean temperature of the earth, may be supposed. 
to have a different result from that intended to be explained; be- 
cause, though water contracts more than solids for equal diminu- 
tions of temperature, yet the thickness of the solid part of the 
* The coast of Sweden is gradually rising above the level of the sea; that of 
Greenland is gradually sinking; the coast of Chili was suddenly elevated during 
an earthquake in 1822; the repeated elevation and subsidence of the Temple of 
Serapis, on the shore of the Mediterranean, are all considered well authenticated 
facts, and demonstrate these variations in the level of the land without the neces- 
sity of adducing any of the numerous and well known effects of volcanic agency 
in producing elevation and subsidence. From recent observations it is also ren- 
dered highly probable that an area of 4,000,000 square miles is gradually sinking 
lower and lower in the Pacific Ocean. 
Vol. xu1x, No. 2.—July-Sept. 1845. 37 
