266 
GEOLOGY OF THE SECOND DISTRICT, 
TRANSITION ROCKS OF ESSEX COUNTY. 
67. 
Potsdam Sandstone. 
Having treated in detail of the primary rocks of Essex county, I proceed to speak of the 
sedimentary deposits. By reference to the map, it will be seen that they occupy merely a 
narrow belt along the shore of Lake Champlain. The uplift which elevated the great mass of 
primary, broke off from the main mass of the sedimentary rocks merely their western edge, 
producing thereby a solution of continuity between those upon the west, and those which 
lie upon the east side of the lake. These masses spread out and occupy a much greater 
space upon the Vermont than upon the New-York side ; still, the latter are well worthy of a 
careful examination. 
