+ 
130 PRIMORDIAL—WAPPINGER LIMESTONES. 
of the means already in their hands for similar work on 
other members of this class of bodies. 
JANUARY 27, 1886—FORTY-THIRD REGULAR MEETING. 
Charles B. Warring, Ph.D., chairman, presiding. 
The following paper was read: 
‘S PRIMORDIAL ROCKS OF THE WAPPINGER VALLEY LIME- 
STONES.”’ 
BY PROF. WILLIAM B. DWIGHT. 
The presence of rocks of the Potsdam group in asso- 
ciation with the limestones and shales of Dutchess 
county, N. Y., has long been suspected on stratigraphic 
grounds, but until the present time this fact has never 
been proved by positive paleontological evidence. 
At the bases of Fishkill and Stissing mountains, a 
thick stratum of quartzyte is found between the under- 
lying Archean of those mountains, and the overlying 
limestones, now known to be respectively Calciferous 
and Trenton. This quartzyte shows planes of stratifica- 
tion, and is conformable to the overlying strata of lime- 
stone. Obviously, by its stratigraphic position, it ap- 
pears to represent the Potsdam group, and this assign- 
ment has been made for it, in the localities mentioned, 
by Prof. Mather, Prof. J. D. Dana and others. 
Notwithstanding that considerable search has been 
made, no fossils have yet been found in this quartzyte 
stratum, by which this reasonable hypothesis might be 
established. I am not aware that any geologist has here- 
tofore found reason to suspect the presence of a Primor- 
dial stratum among the limestones of the region, and cer- 
tainly I have had no such expectations myself. The 
observations made during the last few years in the 
Wappinger valley (or ‘‘ Barnegat’’) limestones, have 
definitely proved them to be composed extensively and 
continuously of conformable strata of the Calciferous 
14 
