Trains of Boulders, in Berkshire, Mass. 323 
its moorings, to rip off, assisted with its aid, the outcrops of 
the hardest strata, to grind up and strew wide their fragments, 
to scour down the whole rocky floor, and, gathering energy 
with resistance, to sweep up the slopes and over the highest 
mountains.” 
Let us endeavor to dilate our thoughts to a just conception 
of the scene here feebly hinted at; let us picture an ocean 
freighted with its ponderous bergs and fields of ice, rushing 
across the tops of the mountains, and thrown, by the earth- 
quake undulations of its temporary bed, into a series of enor- 
mous billows, each of which would possess a breadth, as it can 
be shown, of several miles, and a velocity of from five to ten 
miles per minute; and then advert to what would happen as 
the vast masses of solid ice, rivalling in magnitude the hills 
themselves, and borne forward with almost the velocity of a 
cataract, impinged with full momentum against the summits of 
the higher ridges. While a wide, diffused sheet of fragment- 
ary matter, the mingled wreck of all the strata, would be 
driven along at the bottom of the rapidly moving flood, scour- 
ing the rocky floor, and grinding itself into rounded forms by 
its rolling motion and tremendous attrition, the summits of 
the Yet submerged hills would be shot away as it were by the 
striking of the rushing ice, and an enormous speed imparted 
to the broken pieces. As this speed would be sustained by 
the swift motion. of the general current, and the yet greater 
velocity of the vast billows or waves of translation, the projec- 
tile distances of the blocks, or their course through the water, 
ore they came to final rest, might be even as much as 
Several miles.' That the fragments might be conveyed thus 
Ssions by a violent stroke of a large mass of floating ice, is strikingly con- 
firmed, we think, by the interesting fact already observed by Dr. Hitchcock, that 
See the places where the ragged fragments were torn off, and the fracture 
Pi ick Sgestion here made, that the crest of the ridge was scooped off at each of 
i wy ot the n rounded drift, 
EM indentations in the backbone of the ridge, we should look for a smooth and 
line, e curving surface in the shallow notch, whereas we really see a broken out- 
: the ragged edges of the strata, indicating that the top of the moun- 
