340 
GEOLOGY OF THE FOURTH DISTRICT 
The hills covered with drift along the south side of the Ridge road, and upon the shore of 
Lake Ontario, exhibit very similar phenomena. Some of the bluffs on ihe lake shore present 
large accumulations of clay and gravel above the boulders. 
101 . 
Section of Drift and Boulder formation, Greece, Monroe county. 
The illustration above is from a bluff in Monroe county, on the lake shore. The lower 
stratified deposit consists of gravel and loam, which is succeeded by a range of granitic 
boulders mingled with clay and gravel, and covered to the depth of several feet more with 
gravelly clay. The lower stratified deposit is evidently the product of a period distinct from 
that above, which presents no lines of stratification. 
The bluff has been undermined by the action of the waves, and trees and stumps have been 
thrown, and often remain standing upright in the beach below; and at a cursory examination, 
many of them might be supposed to have grown there, so deeply imbedded and firmly are the 
roots fixed in the sand and pebbles. 
Huge blocks of the Medina sandstone are sometimes found resting on the top of the Niagara 
limestone ; these are scarcely worn, and appear to have been lifted from the upper outcropping 
edge of the mass, and dropped upon the limestone above. In like manner, numerous masses 
of the Niagara limestone are drifted forward, resting on the Onondaga salt group. Upon the 
terrace formed by the Corniferous limestone, we find great numbers of immense blocks of 
limestone from the upper part of the Onondaga salt group. This portion has been before 
described as an impure argillaceous limestone, in strata of ten or fifteen feet thickness. These 
masses frequently lie in their original position, as if the edge of the stratum had been enclosed 
irv a mass of ice, which an advancing tide carried forward and dropped upon the bottom. 
The unequal hardness in different parts often causes them to be worn into fantastic shapes. 
