78 Geology of America. 
the ice which now surrounds the pole and covers the upper re- 
‘gions of our great mountain chains, is but the remnant of much 
larger masses, which were chiefly seated in high latitudes, and 
were perhaps heaped up near the pole to the depth of ten thou- 
sand feet. When the change of temperature took place, which 
partially dissolved and broke up this mountain of ice, as it may 
be termed, the water, liberated by fusion, would flow off on 
all sides from the pole, forming currents, and bearing with them 
floating masses of ice. The motion of these would be south- © 
ward, like that of the icebergs often seen in the Atlantic, and 
that great floating raft of ice which Captain Parry supposed 
at first to be fixed, but which he afterwards found was in mo- 
tion, bearing him southward with nearly the same speed that 
he travelled northward on its surface.* In moving south- 
ward the currents from the pole would meet the easterly cur- 
rents, be incorporated with them, and the result would be, 
currents compounded of the two—that is, moving in a south- 
easterly direction. And thus icebergs and floating fragments 
of ice, loaded at their bottoms with stones, gravel, and sand, 
and set loose from the polar regions, would be borne along 
south-eastward, producing striae and furrows pointing in that 
direction ; the declivities of hills facing the currents—that is, 
fronting the north-west, when moderately inclined (Corstor- 
phine Hill is an example) would be doubly abraded and grooved, 
because there the onward pressure of the water aided the 
weight of the mass of ice ; on the other hand, declivities front- 
ing the south-east would scarcely feel the action of the cur- 
rents, but would be the seat of eddies, where the clay, sand, 
gravel, and boulders, would be deposited. 
Again, returning to the idea started by Mr Murchison ; if 
the south-easterly currents were occasionally choked with ice, 
which was afterwards torn up and driven along, we can under- 
stand that masses of it loaded with drift might be forced out 
laterally, and lodged on the flanks of the currents, as exempli- 
fied in the river Neva. Mr Murchison’s hypothesis explains 
* The tendency of these masses would not be to move right southward, 
but rather south-westward, owing to the low velocity of revolution they 
brought with them from the higher latitudes. The motion of the combined 
currents however, would still be south-easterly, but a littlemore to the south- 
