Orange Mountain Basalt (NJJo;2)

Orange Mountain Basalt - Basalt, fine-grained to aphanitic, dark-greenish-gray, composed mostly of calcic plagioclase and augite; crystals smaller than 1 mm (0.04 in). Unit consists of three major tholeiitic lava-flow sequences, each about 80 m (262 ft) thick. Lowest flow is generally massive with widely spaced curvilinear joints; middle flow is massive or has columnar joints; lower part of uppermost flow has pillow structures and upper part has pahoehoe flow structures. Thickness in map area is about 160 m (525 ft).

State	New Jersey
Name	Orange Mountain Basalt
Geologic age	Lower Jurassic
Original map label	Jo
Comments	part of the Brunswick Group
Primary rock type	basalt
Secondary rock type
Other rock types
Lithologic constituents	Major Igneous > Volcanic > Mafic-volcanic > BasaltBasalt, fine-grained to aphanitic, dark-greenish-gray, composed mostly of calcic plagioclase and augite; crystals smaller than 1 mm (0.04 in).
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. Owens, James P., Sugarman, Peter J., Sohl, Norman F., Parker, Ronald A., Houghton, Hugh F., Volkert, Richard A., Drake, Avery A., Jr., and Orndorff, Randall C., 1998, Bedrock Geologic Map of Central and Southern New Jersey: U.S. Geological Survey Miscellaneous Investigations Series Map I-2540-B, scale 1 to 100,000, 8 cross sections, 4 sheets, each size 58x41. [http://pubs.er.usgs.gov/publication/i2540B]
Geographic coverage	Bergen - Essex - Hunterdon - Passaic - Somerset - Union