40 
THE GEOLOGIST. 
and the different compositions of the overlying rocks ; these latter 
indicate a rapid motion of the waters^ the under clay on the con- 
trary a quiet subsidence of sediment. 
Beds of marine limestone were found in contact with the coal- 
seams. There is also a regular gradation in the proportion of 
volatile matter in the coal as we cross the Appalachian basin 
north-westward. 
Prof. H. D. Rogers presented more details in relation to the 
striated surfaces of the north-eastern counties of Pennsylvania and 
the adjacent districts of New York, proving, that while the 
scratches which abound on the summits of all the mountain 
ridges in that part of the Appalachian chain observe a nearly 
north and south direction, answering to their prevailing cause 
throughout New England, those on the sides and bottoms of the 
valleys obey with remarkable fidelity all the local deflections 
which a body of moving waters would encounter along the ridges 
and valleys of this entangled range. In the Wyoming valley, 
the summits of mountains elevated 2000 feet above the sea, and 
1500 feet above the valley, are covered mth parallel strise, point- 
ing a little W. of S., but on their slopes in the bed of the valley 
these lines follow other directions conforming to the course 
which any obstructed inundation would pursue. 
Reviewing several of these circumstances Prof. Rogers con- 
cludes that the strise were produced by the friction of the over- 
lying drift itself, urged into rapid motion from the north by one 
or more sudden inundations. From the absence near the sou- 
thern border of the striated region of granitic or other far trans- 
ported northern boulders, he infers that floating ice had no 
agency in furrowing and smoothing the surfaces of the strata. 
The next meeting of the Association will be held at Albany on 
the fourth Wednesday in April, 1843. 
