Passaic Formation gray bed (NJTRpg;5)

Passaic Formation gray bed - Rhythmic cycles 2 to 7 m (7-23 ft) of thick gray-bed sequences (Trpg), termed Van Houten cycles by Olsen (1985), contain basal thin-bedded to finely laminated shale to siltstone, which grade upward through laminated to micro-laminated, locally calcareous mudstone to siltstone and finally into massive silty mudstone. Lowest part of cycle has some desiccation features and local fossils; middle part has highest organic content and the most fossils; highest part contains mudcracks, burrows, and root casts. Gray-bed cycles are abundant in lower half of Passaic Formation and less common in upper half.

State	New Jersey
Name	Passaic Formation gray bed
Geologic age	Lower Jurassic and Upper Triassic
Original map label	Trpg
Comments	Newark Supergroup, Brunswick Group (Lyttle and Epstein, 1987). The Passaic Formation unit description on the map encompasses multiple units (JTRp, JTRpms, JTRps, JTRpsc, JTRpcq, JTRpcl, and TRpg). The units were split into separate records and appropriate descriptions for each were used. Names for units is from digital map.
Primary rock type	fine-grained mixed clastic
Secondary rock type	shale
Other rock types	siltstone; mudstone
Lithologic constituents	Major Sedimentary > Clastic > Mixed-clastic > Siltstone-mudstone (Bed) Sedimentary > Clastic > Mudstone (Calcareous) Minor Sedimentary > Clastic > Mudstone > Shale (Calcareous)
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] Lyttle, P.T., and Epstein, J.B., 1987, Geologic map of the Newark 1 x 2 degree quadrangle, New Jersey, Pennsylvania, and New York: U.S. Geological Survey Miscellaneous Investigations Series Map I-1715, scale 1:250,00. [http://pubs.er.usgs.gov/publication/i1715] Olsen, P.E., 1985, Distribution of organic-matter-rich lacustrine rocks in the early Mesozoic Newark Supergroup, in Robinson, G.R., Jr., and Froelich, A.J., eds., Proceedings of the second U.S. Geological Survey workshop on the early Mesozoic basins of the Eastern United States: U.S. Geological Survey Circular 946, p. 61-64. [http://pubs.er.usgs.gov/publication/cir946]