1892.] . NEW YORK ACADEMY OF SCIENCES. 133 
the particular circumstances under which they were produced. 
The striking analogy which they bear, however, to the strata of the 
middle secondary series both in composition and appearance, and 
their lying in the same unconformable manner upon the previously 
uplifted rocks of the Appalachian group, induce us to consider them 
as deposits from the same mass of waters.’? Accompanying this 
report is a ‘‘ Section from New York to the Delaware River at 
Dingman’s Ferry,’ and where it crosses the Copperas and Green 
Pond mountains the rocks are given as of Middle Secondary age ; 
but on the ‘‘ Geological Map of New Jersey,” finished January, 
1839, the formation was colored as the ‘‘sandstone and conglomerate 
of Green Pond Mountain.” 
Professor Mather, in the ‘‘ Geology of the First Geological Dis- 
trict”? of New York, placed this terrane under the heading of 
“Rocks similar in character to the Shawangunk grit, and the inter- 
stratified and overlying red rocks.”” It was stated that ‘the ob- 
servations on the geological survey of the First district of New York 
do not quite demonstrate the age of this rock; but if the red slates 
and grits on the east side of the Hudson, which are the same as 
those of Pine hill, in Cornwall, Orange county, are the same as 
those of Bellvale mountain near Long pond, and the Green-pond 
mountain, which they strongly resemble, and of which they appear 
to be an extension, they are older than the Middle Secondary sand- 
stone (new red sandstone) of New Jersey, to which Prof. Rogers 
inclines to refer them, and are probably the geological equivalents, 
and in fact identical with the red rocks overlying and interstratified 
with the upper part of the Shawangunk grit.’” 
On the ‘“ Geological map of the State of New York,’ published 
in 1844, the region of Skunnemunk Mountain is colored as belong- 
ing to the Hudson River group. 
The Green Pond Mountain rocks were described under that name 
by Professor George H. Cook in 1868 and referred to the Potsdam.* 
On the geological map showing the distribution of the Azoic and 
Paleozoic formations of New Jersey and Orange County, New 
York, the Green Pond, Bearfort, Bellvale, and Skunnemunk Moun- 
tain ridge is colored as Potsdam, while rocks lying to the east of 
Skunnemunk and Bellvale mountains and between Bearfort and 
Kanouse mountains are colored as of Hudson River age. 
The first fossils in this formation were found by Professor Daniel 
S. Martin in a so-called coal mine on Skunnemunk Mountain, north- 
west of Monroe, Orange County, New York. On October 16, 
1871, the Professor read a paper before the New York Lyceum of 
Natural History, on ‘‘The Coal of Orange County, New York,” 
and stated that ‘‘the coal-mine of Monroe lies upon the western 
side, near the summit of an isolated hill known as Schunemunk 
' Description of the Geology of the State of New Jersey, being a Final Re- 
port, 1840, p. 174. 
2 Geology of New York, Pt. 1, 1843, pp. 362, 363. 
3 Geology of New Jersey, pp. 37, 73, 79-89. 
