On the identity of the “Cattskill” and Chemung Groups. 61 
Art. VIIL—On the identification of the Cattskill Red Sandstone 
Group with the Chemung ; by Prof. A. WINCHELL, (in a letter 
addressed to Prof. Dana.) 
University of Michigan, Ann Arbor, 10th Dec., 1862. 
Dear Sir:—The announcement by Col. Jewett’ of the grounds 
of his disbelief in the existence of the Cattskill group, within 
the State of New York, is producing a sensation among geol- 
Ogists: but it seems to me that no one who has recognized the 
Carboniferous aspect of the fauna of the Marshall group of Mich- 
igan and its equivalents at the West, can feel a particle of sur- 
nse at this announcement; especially if he has been in the 
abit of admitting the equivalency of these western rocks with 
the Chemung of western New York. ou will remember that 
a8 long ago as last March, in referring the rocks of Michigan to 
their New York equivalents in compliance with your request to 
0 80, I expressed my conviction of the equivalency of the Mar- 
shall and Chemung groups, and of their common Carboniferous 
character, and entirely omitted the Cattskill in consequence of 
my disbelief of its existence as a distinct group, and serious 
doubts about the Devonian character of the Old Red Sandstone of 
New York. These doubts originated in the winter of 1859-60, 
and have since been confirmed by observing the close analogy of 
many Marshall fossils with Old Red Sandstone Sree a 
me to include within the Marshall (Chemung) group the Amer- 
X20 representation of that so-called Devonian horizon of the Old 
also be permitted to allude to the interesting co- 
incidence of my having last summer communicated to others the 
°pinion that asthe “Cattskill group” was the only serious obsta- 
“le to the elevation of the New York Chemung, with its western 
gn alents, into the bounds of the Carboniferous system, so that 
obstacle would yet be proved to be imaginary through the obser- 
Vations of some geologist who would show that it does not in | 
Teality tebe the Chemung. nis : 
esearches in the rocks of this age, to whic ave given 
“pecial attention for the past Sichaen monte: have furnished 
me with the data for some interesting conclusions, which I shall 
ae Prepared to present in detail; but the great interest be- 
Sing to the questions affected by my investigations, will per- 
PS justify me in saying at this time, that the following results 
are reached :—Species common to Michigan and Rockford, Ind., 
th, common to Michigan and Burlington, Iowa, 7;—common to 
commen oealites, 3;—common to Rockford, and Missour, 6;— 
a urlington and Missouri, 8 ;—common to Burlington 
and Ohio, Rares Avot to Burlington and New York, 3;—besides 
‘ This Journal, Nov. 1862, (xxxiv, 418). 
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