ICE-PERIOD IN AMERICA. 
89 
acteristic of the rocks in those regions, wher¬ 
ever they are not disintegrating under the 
influence of the present atmospheric agents. 
Upon these surfaces, through the whole ex¬ 
panse of the country, rests the drift, having 
everywhere the characteristic composition of 
glacier-drift, and nowhere that of an aqueous 
stratified deposit, except when afterwards re¬ 
modelled by the action of water. But of this 
stratified drift I shall have occasion to speak 
more in detail hereafter. There is, however, 
one circumstance, of frequent occurrence, along 
our New England shores, requiring special 
explanation, because it is generally misunder¬ 
stood. Along our sea-shore, and even within 
the harbor of Boston, at the base of the har¬ 
bor-islands, as well as the outlet of our larger 
Atlantic streams, numbers of boulders are 
found of considerable size; and this fact is 
often adduced as showing the power of water 
to transport massive fragments of rock to 
great distances, the mineralogical character of 
these boulders being frequently such as to 
show that they cannot have originated in the 
neighborhood of their present resting-places. 
But a careful examination of the surround- 
