Platy limestone and limy siltstone, chert at base (NVSt;0)

State	Nevada
Name	Platy limestone and limy siltstone, chert at base
Geologic age	Silurian to Early Devonian
Original map label	St
Comments	The Chellis Limestone is 1,900 feet thick and the Storff Formation is 3,900 feet thick; both formations are limited to northern Elko County (Coats, 1987). The Roberts Mountains Formation makes up the rest of this unit and ranges from 500 to 1,700 feet thick (Roberts and others, 1967, Kleinhampl and Ziony, 1985, Stewart and McKee, 1977). The Roberts Mountains Formation includes calcisiltite and calcilutite (Coats, 1987), and silty limestone (Stewart and McKee, 1977), all of which was classified as limestone, rather than siltstone, in the lithology coding.
Primary rock type	limestone
Secondary rock type	dolostone (dolomite)
Other rock types	chert; siltstone; shale
Lithologic constituents	Major Sedimentary > Carbonate > Limestone (Bed) Incidental Sedimentary > Chemical > Chert (Bed)Nowhere more than 2% of the Roberts Mountains Formation (Coats, 1987). Sedimentary > Clastic > Mudstone > Shale (Bed) Sedimentary > Clastic > Siltstone (Bed)Possibly minor in rank if calcisiltite of Coats (1987) and silty limestone of Stewart and McKee (1977) are considered better described as calcareous or limy siltstone. Sedimentary > Carbonate > Dolostone (Bed)Possibly minor in rank (tops some exposures of the Roberts Mountains Formation).
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. Coats, R.R., 1987, Geology of Elko County, Nevada: Nevada Bureau of Mines and Geology Bulletin 101, 112 p., 1 pl. Roberts, R.J., Montgomery, K.M., and Lehner, R.E., 1967, Geology and Mineral Resources of Eureka County, Nevada: Nevada Bureau of Mines and Geology Bulletin 64, 152 p., 12 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 - Eureka - Lander - Nye