34 Miscellaneous Notices of American 
Glenn’s Falls, as deseribed by you, bear to some detached 
rolled masses lately found in this maneneawond, about forty 
feet below the surface. These pieces were thrown out in 
digging a well on the side of Prospect hill, about one mile 
from the river—This city is built ona foundation of argil- 
pcstire marl lying in horizontal strata, and containing a con- 
iderable portion of sulphate of magnesia. In front of the 
coisas street there is a steep bank composed of silicious 
— which rises about seventy feet above the surface of the 
iver; as you recede from this, the ground declines ten or 
Gfiane feet to Market square, from whence there is a gradu- 
al ascent for about one mile to the base of Prospect-Hill, on 
the north-west side of which this well was commenced 
-at an elevation of about one hundred and seventy feet. The 
well was sunk about eighty feet, passing almost entirely 
through a solid mass of hard clay, (or pan,) not stratified, 
and containing rounded pebbles of quartz, &c, and rolled and 
water-worn pieces of | imneas ones abovementioned, aspecimen 
of which different from 
any thing of the kind in ‘his pre ts of country—From the 
mouth of the well the hill rises about one hundred and eigh- 
ty feet, with an uniform smooth surface, and falls off gently 
on the south-east, to a low meadow, which divides it from 
the north end of Becraft’s mountain, so called. This is a 
solid mass of grey rock supporting a blue compact limestone ; 
tbe upper strata of both rocks contain a great variety of pe- 
trifactions which have been described by Mr. Eaton re) 
others. Prospect-Hill, on the contrary, oe et no ap 
pearance of rock strata whatever, although on the 
and in the vicinity are found pebbles and rounded masses of 
quartz, granite, gneiss, &c. Among the pebbles we find 
slate of several colours, chlorite, j jasper, basanite, &c.; these 
are also found in connection with a grey sand, which is ta- 
ken from the adjoining vallies for building purposes, and 
which is evidently composed of the particles of disintegrated 
primitive rocks, and presents so strong appearance of alluvi- 
al A one as to be apparent to the most careless observer. 
{t appears therefore evident that this alluvial matter has 
been borne down by the rushing waters from its original 
situation in the a regions of the mois and ea oo 
in its present location. The investigation of this subject 
appears to me of some importance in a geological view. If 
