218 
GEOLOGY OF THE FIRST DISTRICT. 
of some hundreds or thousands of feet more than at present; and by their having been deflected 
in their courses of transportation (as the scratches show,*) by the topographical features of 
the country, which could not have been the case if they had been drifted by the wind in still 
water, on ice. 
(c.) We know of no other cause than currents of water, that could have produced effects 
like those observed ; namely, transportation to great distances, rounded masses of rock, 
scratched surfaces of solid rocks in place, and the scratches in such directions as the topo¬ 
graphical features of the country would give to currents. 
We may therefore adopt the conclusion as almost certain, that currents have flowed from 
the polar regions of the north towards the equator; and as far as we have evidence from the 
observations of Darwin, and others, on the boulders and blocks of the southern hemisphere, 
that similar currents have flowed from the south polar regions towards the equator. Both 
arguments lead to the same general result. It will be shown subsequently that there are 
dynamical laws that must necessarily have caused currents, such as we see the effects of, 
through all time since the ocean has existed, and which would be heightened in effect by the 
refrigeration of the globe, and will render the evidence of refrigeration still stronger. 
It is evident from the phenomena observed, that a change in the relative levels of the ocean 
and the land has taken place since the epoch of the transportation of the drift deposits ; and 
of the physical causes to which such a change of level may be ascribed, we are bound by 
sound reasoning to exclude all that are exterior to the earth. 
Prof. John Phillips has shown, “ that the desiccation of the land is not the effect of the 
general cooling of the globe without change of form; for the effect due to that, is of a con¬ 
trary description: nor of the unequal contraction by cooling of the superficial parts of the 
globe ; for that effect, even through the whole range from boiling heat (212°) to 40° F., would 
be totally inadequate to account for the phenomenon, even if the depth of the ocean be sup¬ 
posed far greater than it is admitted by astronomers to be.”t 
The desiccation of the land, and the occurrence of tropical animals and plants found fossil 
in the cold regions of the earth, have been attempted to be explained by a change in the axis 
of rotation, by which the polar regions would be brought under the equator. Such a change 
would cause a flow of water from the polar regions, to maintain the earth in the form of an 
oblate spheroid, such as is due to the velocity of rotation of the earth ; and without a change 
of form of the solid exterior of the earth, must have buried the equatorial regions under a 
depth of several miles of ocean, and left the polar regions as highly elevated tracts of land. 
This theory would well account for many of the facts of the drift period, but it labors under 
an objection that is insurmountable. Astronomical observations and calculations not only 
afford no support to it, but demonstrate its impossibility, and show that the axis of the earth’s 
rotation is fixed. 
* The boulders show the general result of the direction of transport, the scratches, both the general and local directions. The 
scratches generally conform to the main valley in its lowest part, but are laterally oblique in most instances on its sides, and are 
more or less approaching to a perpendicular direction in the transverse valleys, 
t Phillips, Treatise on Geology. Edinburgh, 1838, p, 279. 
