632 
GEOLOGY OF THE FIRST DISTRICT. 
and the polished surfaces of fissures, the shivered glazed slate, with all its fragments glazed 
as if rubbed over each other, and the newer pitching under more ancient rocks, lead to the 
conclusion that lateral motion has been produced by some cause. 
1. It is generally admitted that the earth is in the state of a cooling body ; at least, that it 
has a mean temperature on its surface much higher than that of the regions of space in which 
it performs its revolutions around the sun; that the interior of the earth is more heated than 
the exterior, and that it loses more caloric by radiation than it receives from the sun; in all 
which respects it is in the state of a cooling body. 2. Cooling bodies diminish in volume. 
3. Bodies revolving on axes, if they diminish in diameter, increase in their velocities of 
rotation. Applying these principles to the earth, if the earth has increased in its velocity of 
rotation, either gradually or paroxysmally, the ocean, being a fluid, would not, in consequence 
of its inertia, immediately partake of this increased velocity; and as the earth revolves from 
west to east, a current of greater or less strength would set to the westward over the whole 
ocean, but strongest at the equator. So also with the solid mass of the exterior of the globe ; 
its inertia would also tend to cause it to press to the westward with a power depending on its 
mass and its increased velocity of rotation, and if there were lines at which yielding could 
take place, slight motion might thus be expected to be produced, and effects on strata such 
as we see, would be the natural result of such causes. 
If the interior of the earth be fluid, or partially so, and the solid exterior of the earth 
floating as it were upon it, any change of the velocity of rotation might be expected to 
produce still stronger effects, and changes of longitude of masses of the earth’s surface 
be effected, such as we see evidences of in the crumpled, wrinkled and folded strata, which, 
if laid out (developed in a mathematical sense), would occupy much wider areas than they 
do at present. 
The above is suggested as a possible, perhaps a probable, cause of the folding of the 
strata of the eastern part of the United States, in connection with the tangential force, or 
lateral thrust, arising from secular refrigeration, and consequent contraction of the earth, and 
from subsidence of portions of the earth’s surface, such as that described by Darwin and 
Dana in the South Pacific, where sixteen millions of square miles area are gradually sinking, 
and also that of Greenland, which is settling below the water level. 
It may be seen from what precedes in this volume, that most of the phenomena of physical 
geology may be referred to the effects of caloric, gravitation, and of the rotation of the earth 
on its axis. 
If we suppose that there may have been variations in the length of our day, and if those 
variations occurred paroxysmally, the change in the velocity of the revolving system would, 
in consequence of its inertia, have a tendency to a retrograde or westwardly motion, until 
it should have acquired the increased velocity. The materials on the exterior portions of the 
mass of the earth would, therefore, press westwardly with a force proportioned to the increased 
velocity of the system and its mass; and if the solidified materials of the earth yielded along 
the lines of least resistance, changes of longitude of points on the surface must have been 
