|Geologic age||Middle Devonian|
|Comments||part of Hamilton Group 600-1500 ft. (180-460 m). Secondary unit descriptions from USGS Lexicon website (ref. NY046) and references NY015, NY022, NY023, and NY024: Marcellus Shale of the Hamilton Group is the oldest of the extensive black gas shales. Unit crops out in the Valley and Ridge from southeastern NY to northern WV. The Marcellus or its partial equivalent the Millboro Shale, is present in the subsurface in NY, PA, OH, western MD, VA, WV, and northeastern TN. Consists for the most part of sooty black shale and a few beds of medium-gray shale and limestone nodules or beds of dark gray to black limestone. Marcellus is approximately 1,000 ft thick in central PA, but thins to the north, west, and south. Feathers out in eastern OH, western WV, and southwestern VA. The Cherry Valley Limestone Member is an extensive unit in the subsurface of NY, PA, and WV (deWitt and others, 1993). Marcellus Formation will be formally raised to subgroup status within the Hamilton Group and be divided into a lower Union Springs Formation and an upper Mount Marion Formation (in eastern NY) and an upper Oatka Creek Formation (in central and western NY) in a publication by Ver Straeten and others (in prep). Union Springs Formation will incorporate three members across NY: The Bakoven Member (geographically extended across the State of NY), the Stony Hollow Member (restricted), and the Hurley Member (new). The Hurley underlies the Cherry Valley Member at the base of the laterally equivalent Mount Marion and Oatka Creek Formations. By extending the Cherry Valley across the State, it now includes strata formerly assigned to the upper part of the Stony Hollow Member. The revised Cherry Valley is composed of two lithosomes; an eastern sand-dominated facies and a central to western carbonate-dominated facies. Strata above the Cherry Valley in the Oatka Creek remain unnamed, though they bear some resemblance to the Chittenango Shale Member of the Mount Marion Formation of west-central NY (Ver Straeten and others, 1994). Cardiff Shale - Named for village of Cardiff, Onondaga Co., west-central NY. Named as top division of Marcellus beds or stage [broad sense]. Consists of dark, calcareous and black, slaty shales with thin layers of fossiliferous limestones, both of which weather to light ashen gray. Thickness is 50 to 100 ft. Overlies Stafford limestone; underlies Skaneateles shale of Hamilton. Age is Middle Devonian (Clarke and Luther, 1904). Chittenango Shale - Named as member of Marcellus shale. Named for village of Chittenango, central NY. Consists of jet-black, fissile, noncalcareous shale. Was separated from Oatka Creek shale of western NY because it is noncalcareous, nearly barren of fossils, and represents only part of the time interval represented by Oatka shale. Thickness is 120 ft at type section. Overlies Cherry Valley limestone member of Marcellus; interfingers with blue-black Cardiff shale above (Cooper, 1930). Union Springs member of Marcellus formation named in this report. Consists of alternating beds of black limestone and sooty shale overlying Onondaga limestone and underlying Cherry Valley limestone member of Marcellus from Unadilla Valley westward to Seneca Lake. Thickness is 17 ft at type section in Wood's quarry. At Marcellus it is 13 ft thick, at Oneida Creek above Stockbridge Falls, 25 ft, and on Flint Creek, near Phelps, 9 ft. It is not known west of Phelps, Ontario Co., NY (Cooper, 1930).|
|Primary rock type||black shale|
|Secondary rock type||limestone|
|Other rock types|
Sedimentary > Clastic > Mudstone > Shale > Black-shale
Sedimentary > Carbonate > Limestone
NYS Museum, NYS Geological Survey, NYS Museum Technology Center, 1999, 1:250,000 Bedrock geology of NYS, data is distributed in ARC/INFOr EXPORT format (with ".e00" extension) in 5 seperate files based on printed map sheets, http://www.nysm.nysed.gov/gis.html.
D. W. Fisher; Y. W. Isachsen, L. V. Rickard, 1970, Geologic Map of New York State, consisting of 5 sheets: Niagara, Finger Lakes, Hudson-Mohawk, Adirondack, and Lower Hudson, New York State Museum and Science Service, Map and Chart Series No. 15, scale 1:250000.