On the Lericary Formaiions of the Hudson. 229 
as forming a level plain of some extent, on which the village 
and several gentlemen’s country seats are situated. I be- 
lieve a plain of similar elevation, may be traced in many other 
parts, bordering on the Hudson. 
Between Hyde Park and Rhinebeck, are extensive depo- 
sitions of clay. 
Albany is built on the clay marl formation, and in this 
respect resembles London. ‘The ground is traversed by nu- 
merous ravines. In the vicinity, the cascades of Arno and 
Tivoli, and the rapids of Norman Kill, which every one who 
sees will admire, are caused by the torrents wearing away the 
higher strata, until they arrive at the solid strata of the transi- 
tion slate. 
At Greenbush is an extensive formation of the adhesive 
slate. Dr.#T. Romeyn Beck has deposited specimens in the 
Cabinet of the Lyceum of Natural History, in Albany. 
At Troy, the clay marl is abundant, and contains fossil 
wood, ‘The plain above the city, from whence there is a fine 
distant view of the falls of the Mohawk, is composed of dilu- 
vial debris. The height of the formation at this place is pro- 
bably the same as at Hyde Park and Marlborough. The 
strata, in this vicinity, have been described by Mr. Eaton in 
his Index to the Geology of the Northern States, 
At Schenectady the same formations are visible; they also 
form the whole tract of country, between that city and Al- 
bany. 
These strata may undoubtedly be classed with the ter- 
tiary clays of Europe, but they vary in some particulars. 
The London clay contains numerous fossil shells, and the 
bones of extinct animals, but none have hitherto been found, 
in the clay marl on the North river. 
From the large depositions of adhesive slate, they agree 
more precisely with the formations at Mont Martre, near 
Paris, where there are alternating strata of this mineral, and 
clay marl transition. 
The menilite has not yet been found on the shores of the 
Hudson, although this is a position where we may expect it to 
be discovered, 
126 Broadway, New-York. 
