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Towaco Formation

Towaco Formation (Olsen, 1980) - Reddish-brown to brownish-purple, fine- to medium-grained micaceous sandstone, siltstone, and silty mudstone in upward-fining sequences 1 to 3 m (3-10 ft) thick. Distributed throughout formation are eight or more sequences of gray to greenish- or brownish-gray, fine-grained sandstone, siltstone and calcareous siltstone and black, microlaminated calcareous siltstone and mudstone containing diagnostic pollen, fish and dinosaur tracks. Sandstone is commonly trough cross laminated; siltstone is commonly planar laminated or bioturbated, but can be indistinctly laminated to massive. Thermally metamorphosed into hornfels where in contact with Hook Mountain Basalt. Conglomerate and conglomeratic sandstone with subrounded quartzite and quartz clasts in matrix of light-red sand to brownish-red silt (Jtc) interfingers with rocks of the Towaco Formation north and west of New Vernon. Maximum thickness is about 380 m (1,250 ft).
StateNew Jersey
NameTowaco Formation
Geologic ageLower Jurassic
Original map labelJt
CommentsNewark Supergroup, Brunswick Group (Lyttle and Epstein, 1987). Units Jt and Jtc are described together on printed map. The units were split into separate records and appropriate descriptions for each were used.
Primary rock typesandstone
Secondary rock typesiltstone
Other rock typesfine-grained mixed clastic; conglomerate
Lithologic constituents
Major
Sedimentary > Clastic > Mixed-clastic > Siltstone-mudstone (Bed)silty mudstone; microlaminated calcareous siltstone and mudstone containing diagnostic pollen, fish and dinosaur tracks.
Sedimentary > Clastic > Sandstone (Bed)reddish-brown to brownish-purple, fine- to medium-grained micaceous sandstone, sandstone is commonly trough cross laminated
Minor
Sedimentary > Clastic > Siltstone (Bed)siltstone and calcareous siltstone and black, microlaminated calcareous siltstone and mudstone containing diagnostic pollen, fish and dinosaur tracks.
Incidental
Sedimentary > Clastic > Conglomerate (Bed)reddish-brown to brownish-purple, fine- to medium-grained micaceous sandstone, sandstone is commonly trough cross laminated
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.
Olsen, P.E., 1980, The latest Triassic and Early Jurassic formations of the Newark basin (eastern North America, Newark Supergroup); stratigraphy, structure, and correlation: New Jersey Academy of Science Bulletin, v. 25, no. 2, p. 25-51.
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.
Geographic coverageBergen - Essex - Morris - Passaic - Somerset - Union

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