Fl ld cl a rl 
7 ¥ 
5 ha Hes ol ula Sail ln a 9 
S. W. Ford—Primordial Fossils of New York. 37 
ies occurring in the Troy P iat beds ; and when we 
necessary to appeal to an overturned and led fold, instead 
of a fault, to explain the geological areoue ‘of the region. 
ADDITIONAL Nore. 
Since the above was written, I have examined nearly all of the 
bia County ; also the still site acuity locality which oe st 
about four miles east of nebeck, in Dute 
my excursion was a pachewiek hurried one, and. m cath es 
fossils at the several points visited was in the m srctcte gist 
the impression made upon my mind by the facts ahaa 
yet strong that — was aight j in placing all of these Oech in 
the same great group or zone. The limestones east of Rhin 
beck village are more altered than those of Troy and Suity vain 
fauna, In the course > of my s stu dies, I hed nearly all of the 
exposures of rock along the Hudson River Railroad, and also, to 
some extent, those “infgeias ‘yer nd beyond the bays ‘and marshes 
(for the course of the g t Appalachian break, though here for 
st part a north- eh wey one, is, in certain places, Cant 
undulated), from Schodack Landing to the first railroad eee 
h 
bape miles south of Rhine Cliff station, at which poin re is 
a splendid example of unconformability between the hider one 
newer he rock through which the tunnel 
groups. passes 
almost certainly the Hudson River slate, while the strata sa hiah 
wall against it are in all probability Primordial. The Lower 
Potsdam group in Canada, below Quebec, has a thickness of = 
least 2,000 feet, and its thickness is manifestly ve 
Eastern New York. In c epee weet of the generally abide 
pane rs of the folds of the region to the course of the fault re- 
ferred to, cross-sections of some eof ‘the more easterly folds and 
ridges are constantly appearing in passing southward along the 
river, and excellent Spponeatties for their detailed ei are 
thus } presented. | 
Johnstown, N. Y., May 31st, 1884. 
