1892.] NEW YORK ACADEMY OE 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 1(J, 

 1871, the Professor read a paper before the NeAV 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. 



