Geology and Mineralogy of a part of Massachusetts, &e. 25 
10. op RED sanpstone. Werner. 
This rock is mentioned on the authority of Prof. Eaton.* 
It is found in small quantity in Grafton and Sand Lake, and 
in pon quantity in Nassau. It appears to rest on gray 
acke. 
11. TRANSITION SHELL LIMESTONE. Cleaveland. 
Colored Orange. 
Near the city of Hudson occurs in quantity a shell lime- 
stone, which corresponds in its relation to argillite and gray 
wacke, and in its general character, to the oldest shell lime- 
stone, or transition shel! limestone, described in Cleave- 
land’s Mia. p. 163—4, and by European geologists. I 
have therefore, BITE it this appellation. The extent of it 
Tam notable to state. Itcontains an abundance of petrifac- 
tions. It is roam as marble, and, as it takes a fine polish, 
the differently colored shells give it a beautifully varie- 
gated appearance. It is well known in most cabinets 
of minerals. It is associated with compact, bluish lime- 
stone without shells. To this rock probeey. belongs the 
limestone containing terebratulites, mentio rof. 
Eaton, as found in the town of ihashineks The same 
organic remains are found in the shell limestone at Hud- 
son. To the same rock may be referred the compact 
limestone, found by Professor Eaton a few miles south of 
Troy. 
ALLUVIAL. 
The common alluvial deposites of sand, gravel, beds of 
potters’ clay, &c. are found abundantly along most of the 
streams. e alluvion of a epee to often from half 
a mile toa mile in width, the wider alluvion of the 
Hudson in this section, fide yi vitsubelted nothing of spe- 
cial interest. Buried trees of different kinds are found on 
these rivers at various depths, more or less decayed ac- 
eording to obvious circumstances. 
Geol. and Ag. Survey of Rensselaer County, p. 11. 
—No. I. 4 
Vou. Vill, 
