Trans. N. Y. Ac. Sez. == 58 Dec. 12, 
able proof should be found of this, if it is true. At present no positive 
assertions could be made, and the duty devolves on the geological. 
members of the Academy to rid the subject of doubt. 
The fossils in the boulder referred to by Mr. Britton prove to have 
come from the Schoharie Grit. In its original condition this was a 
hard, compact blue limestone, but is here presented in a leached state, 
by the passage of waters containing carbonic acid, with a loss of its 
lime, color, and density. It was derived from northern New Jersey, to 
which locality a belt of this rock runs down from Schoharie county. 
Its transit by ice was effected without doubt through the valley of the 
Hackensack, which lies east of the Orange Mountains and west of the 
Palisades. This glacial movement is indicated by the direction of the 
strie observed by Mr. Britton, as well as of those in the Hackensack 
valley. 
Mr. A. A. JULIEN recalled the results of his lithological examination 
of the serpentines both of Staten Island and of Hoboken, presented be- 
fore the Academy two years ago, in which it was shown that sections of 
all these rocks abounded in minute fragments of more or less altered 
amphibole. The conclusion then stated, that these serpentines must 
be certainly derived trom hornblende schist, was confirmed by the in- 
teresting discovery of the latter rock, both in well-boring and on 
Brighton Point. Serpentines of the same general character and origin 
occur frequently throughout New York and Westchester counties. 
The mineral serpentine is also found in small quantity as a vein-deposit, 
not pseudomorphous, like the main mass, but presenting an amorphous 
material with banded vein-structure, associated with magnesite, dolo- 
mite, etc.; e. g., the marmolite of Staten [sland, a translucent green 
variety found at Hoboken, and also at West 6oth street on New York 
Island, etc. At all these localities the amphibole survives in a more or 
less altered condition; e. g., the tremolitic talc schists and slaty tremo- 
litic serpentines of Staten Island and Hoboken, the hydrous antho- 
phyllyte and unaltered tremolyte rock of West 6oth street, New York, 
the tremolitic amphibolyte of New Rochelle and Rye, in Westchester 
county, etc. 
Mr. BRITTON confirmed the last remarks, by the statement that a 
stratum of material, strongly resembling the hydrous anthophyllyte of ~ 
New York, had been struck at the bottom of one of the wells on Staten 
Island ; also that veins of mixed serpentine and calcite were observed 
at Stapleton, possessing a banded structure parallel to their walis. At 
that point the apparent thickness of the serpentine bed is 150 feet, but 
the crest of the hill is composed of talcose schist. 
Mr. W. LE CONTE STEVENS then read a paper on ‘THE MAM- 
MOTH CAVE OF KENTUCKY.” 
