Shale and thin-bedded or laminated limestone; also thinly interbedded limestone and chert (NVCAt;0)

State	Nevada
Name	Shale and thin-bedded or laminated limestone; also thinly interbedded limestone and chert
Geologic age	Middle Cambrian to Late Cambrian
Original map label	Ct
Comments	Shwin Formation contains the only volcanic rocks in the Middle and Upper Cambrian sequence (Stewart, 1980); these rocks include greenstone and phyllite derived from dolerite (diabase) (Stewart and McKee, 1977). The Tybo Shale has been reassigned to the Dunderberg Shale and the term abandoned (Kleinhampl and Ziony, 1985); the shale is mapped within this unit although the rest of the Dunderberg Shale is mapped within unit NVCc. Exposed sections of the Preble indicate 5,000 feet thickness but geologists have estimated 12,000 to 15,000 feet (Willden, 1964). The Emigrant Formation is at least 1,500 to 2,000 feet (Albers and Stewart, 1972). The Crane Canyon Formation is considered to be several thousand feet thick (Stewart and McKee, 1977). In Elko County, includes small outcrop of undifferentiated strata mapped primarily in NVCc (Coats, 1987).
Primary rock type	shale
Secondary rock type	limestone
Other rock types	chert; siltstone; quartzite; diorite; conglomerate
Lithologic constituents	Major Sedimentary > Carbonate > Limestone (Bed)Often lenticular. Sedimentary > Clastic > Mudstone > Shale (Bed)May be calcareous or phyllitic, especially in the Preble Formation. Partially metamorphosed to slate in the Crane Canyon Formation. Incidental Sedimentary > Clastic > Conglomerate (Bed) Sedimentary > Clastic > Siltstone (Bed)Locally abundant in the Crane Canyon sequence but rare or not present elsewhere. Sedimentary > Chemical > Chert (Bed)Possibly minor in rank (abundant in the Emigrant Formation at upto 20%) but rare or not present elsewhere. Metamorphic > QuartziteLimited to minor occurrances in the Preble Formation where it grades downward into the Osgood Mountain Quartzite. Igneous > Plutonic > Dioritic > Diorite (Dike or sill)Mostly metamorphosed to greenstone and phyllite.
Map references	Stewart, J.H., and Carlson, J.E., 1978, Geologic Map of Nevada: U.S. Geological Survey and Nevada Bureau of Mines and Geology, 1:500,000 (not part of any formal series, printed and distributed by the U.S. Geological Survey, G75163, reprinted, 1981, G81386).
Unit references	Stewart, J.H., and Carlson, J.E., 1978, Geologic Map of Nevada: U.S. Geological Survey and Nevada Bureau of Mines and Geology, 1:500,000 (not part of any formal series, printed and distributed by the U.S. Geological Survey, G75163, reprinted, 1981, G81386). Stewart, J. H., 1980, Geology of Nevada: A discussion to accompany the Geologic Map of Nevada: Nevada Bureau of Mines and Geology Special Publication 4. Stewart, J.H., and McKee, E.H., 1977, Geology, Pt. 1, in Geology and Mineral Deposits of Lander County, Nevada: Nevada Bureau of Mines and Geology Bulletin 88, p. 1-59, 3 pl. Willden, R., 1964, Geology and Mineral Deposits of Humboldt County, Nevada: Nevada Bureau of Mines and Geology Bulletin 59, 154 p., 3 pl. Albers, J.P., and Stewart, J.H., 1972, Geology and Mineral Deposits of Esmeralda County, Nevada: Nevada Bureau of Mines and Geology, 80 p., 2 pl. Kleinhampl, F.J., and Ziony, J.I., 1985, Geology of Northern Nye County, Nevada: Nevada Bureau of Mines and Geology Bulletin 99A, 172 p., 2 pl.
Geographic coverage	Elko - Esmeralda - Humboldt - Lander - Nye - Pershing