Bushkill Member (NJOmb;8)

Bushkill Member (Drake and Epstein, 1967) - Interbedded medium- to dark gray, thinly laminated to thick-bedded shale and slate and less abundant medium-gray to brownish-gray, laminated to thin-bedded siltstone. To the southwest, fine-grained, thin dolomite lenses occur near base. Complete turbidite sequences (Bouma, 1962) occur locally, but basal cutout sequences (Tbcde, Tcde or Tde) dominate. Conformable lower contact is placed at top of highest shaly limestone; elsewhere, lower contact is commonly strain slipped. Correlates with graptolite Climacograptus bicornis to Corynoides americanus zones of Riva (1969, 1974) (Parris and Cruikshank, 1992). Thickness ranges from 1,250 m (4,100 ft) in Delaware River Valley to 457 m (1,500 ft) at New York State line.

State	New Jersey
Name	Bushkill Member
Geologic age	Middle Ordovician
Original map label	Omb
Comments	Martinsburg Formation
Primary rock type	slate
Secondary rock type	shale
Other rock types	siltstone; dolostone (dolomite)
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Shale (Bed) Metamorphic > Metasedimentary > Metaclastic > Slate (Bed) Minor Sedimentary > Clastic > Siltstone (Bed) Incidental Sedimentary > Carbonate > Dolostone (Lense)
Map references	Dalton, R. F., Herman, G. C., Monteverde, D. H., Pristas, R. S., Sugarman, P. J., 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) export file: geology.e00, scale 1:100,000, unit description files: cslegend.pdf and nlegend.pdf, metadata: metast.pdf.
Unit references	Dalton, R. F., Herman, G. C., Monteverde, D. H., Pristas, R. S., Sugarman, P. J., 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) export file: geology.e00, scale 1:100,000, unit description files: cslegend.pdf and nlegend.pdf, metadata: metast.pdf. 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, scale 1 to 100,000, 4 cross sections, 2 sheets, size 56x40; 58x41. [http://pubs.er.usgs.gov/publication/i2540A] Drake, A.A., Jr., and Epstein, J.B., 1967, The Martinsburg Formation (Middle and Upper Ordovician) in the Delaware Valley, Pennsylvania-New Jersey: U.S. Geological Survey Bulletin 1244-H, p.H1-H16. [http://pubs.er.usgs.gov/publication/b1244H] Bouma, A.H., 1962, Sedimentology of some flysch deposits; a graphic approach to facies interpretation: New York, Elsevier Publishing Co., 168 p. Riva, John, 1969, Middle and Upper Ordovician graptolite faunas of St. Lawrence lowlands of Quebec and Anticosti Island, in Kay, Marshall, ed., North Atlantic; geology and continental drift: American Association of Petroleum Geologists Memoir 12, p. 513-556 Riva, John, 1974, A revision of some Ordovician graptolites of eastern North America: Paleontology, v.17, pt. 1, p.1-40. Parris, D.C., and Cruikshank, K.M., 1992, Graptolite biostratigraphy of the Ordovician Martinsburg Formation in New Jersey and contiguous areas: New Jersey Geological Survey, Geological Survey Report 28, 18 p.
Geographic coverage	Bergen - Hunterdon - Morris - Passaic - Sussex - Warren