Buttermilk Falls Limestone and Onondaga Limestones, undivided

Buttermilk Falls Limestone in southwestern part of outcrop belt grades into Onondaga Limestone along strike to northeast. The transition occurs north of Millville. Buttermilk Falls Limestone (Middle Devonian) (Willard, 1938) - Light- to medium-light-gray-weathering, medium- to dark-gray, thin- to medium-bedded, fossiliferous, flaggy, clayey to silty limestone and nodular black chert. Lower contact grades downward through several meters (feet) of silty limestone to interbedded limestone and calcareous siltstone of the Schoharie Formation. Thickness is approximately 82 m (270 ft). Onondaga Limestone (Middle Devonian) (Vanuxem 1840) - Light-medium-gray- weathering, medium gray, fine-grained, thin- to thick-bedded fossiliferous limestone. Black chert more abundant in upper half of unit. Lower contact grades into interbedded limestone and calcareous siltstone of the Schoharie Formation. Thickness approximately 60 m (200ft).
State New Jersey
Name Buttermilk Falls Limestone and Onondaga Limestones, undivided
Geologic age Middle Devonian
Lithologic constituents
Major
Sedimentary > Carbonate > Limestone (Bed)Buttermilk Falls Limestone - Light- to medium-light-gray-weathering, medium- to dark-gray, thin- to medium-bedded, fossiliferous, flaggy, clayey to silty limestone. Onondaga Limestone - Light-medium-gray- weathering, medium gray, fine-grained, thin- to thick-bedded fossiliferous limestone.
Sedimentary > Chemical > Chert (Bed)Buttermilk Falls Limestone - nodular black chert. Onondaga Limestone - Black chert more abundant in upper half of unit.
References

Dalton, R.F., Herman, G.C., Monteverde, D.H., Pristas, R.S., Sugarman, P.J., and Volkert, R.A., 1999, New Jersey Department of Environmental Protection, Bedrock Geology and Topographic Base Maps of New Jersey: New Jersey Geological Survey CD Series CD 00-1; ARC/INFO (v. 7.1), scale 1:100,000.

Drake, Avery A. Jr.,Volkert, Richard, A., Monteverde, Donald H., Herman, Gregory C., Houghton,Hugh F., Parker, Ronald A., and Dalton, Richard F., 1996, Bedrock Geologic Map of Northern New Jersey: U.S. Geological Survey Miscellanenous Investigations Map I-2540-A, 4 cross sections, 2 sheets, size 56x40; 58x41, scale 1:100.000.

https://pubs.er.usgs.gov/publication/i2540A

Willard, Bradford, 1938, A Paleozoic section at Delaware Water Gap: Pennsylvania Geological Survey, 4th series, Bulletin G-11, 35 p.

Vanuxem, Lardner, 1840, Fourth annual report of the geological survey of the third district: New York Geological Survey Annual Report 4, p. 355-383.

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Counties Sussex