322 Rogers’s Account of two Remarkable 
the ratio of the square of the velocity, a very moderate ad- 
dition to this speed is compatible with the transportation of 
the very largest erratics anywhere to be met with, either in 
America or Europe. 
* Holding in view these demonstrable conclusions, let us 
consider the far more enormous velocity which a broad, general 
current would derive from that mode of paroxysmal action, 
earthquake undulation, which constitutes, as we have endeav- 
ored to show, an essential feature in all movements of eleva- 
tion. Regarding such disturbances as a true billowy pulsation 
of the flexible crust of the globe, we have deduced, from data 
connected with some of the best authenticated earthquakes, 
the extraordinary progressive velocity of the undulations of the 
ground, and have shown that, when the pulsation has been 
imparted to the sea, the vast waves engendered have moved 
at the amazing speed of five miles or more per minute. 
Making every abatement for resistance from the comparative 
shallowness of a continental inundation, the phenomena © 
earthquakes fully justify us in the belief that the broad and 
rapid onward undulations of the ground would be propagated 
to an uplifted sea above, and the gigantic billows be propelled, 
across the surface of the heaving land, with a velocity, and a 
propulsive energy, approached by no other possible terrestrial 
current. 
* If we will conceive, then, a wide expanse of waters, less, 
perhaps, than one thousand feet in depth, dislodged from some 
high northern or circumpolar basin, by a general lifting; of 
that region, of perhaps a few hundred feet, and an equal su 
sidence of the country south, and imagine this whole mass 
converted by earthquake pulsations, of the breadth which such 
undulations have, into a series of stupendous and rapid-moving 
waves of translation, helped on by the still more rapid flexures 
of the floor over which they move, and then advert to the 
shattering and loosening power of the tremendous jar of the 
earthquake, we shall have an agent adequate, in every way; t° 
produce the results we see,—to float the northern ice from 
