Where: Idaho (43.8° N, 111.5° W: paleocoordinates 1.7° N, 41.6° W)

• small collection-level geographic resolution

When: Spirifer brazerianus zone, Cherty Limestone Member (Monroe Canyon Formation), Meramecian to Meramecian (343.0 - 323.2 Ma)

• The Mississippian rocks in the Chesterfield Range consist of Lodgepole limestone overlain by a 1900ft. limestone-sandstone sequence here designated the Chesterfield Range Group. The lower terrigenous part, about 965 ft. thick is the Little Flat Fm., it has a basal siltstone member, a middle sandstone member, and an upper sandy limestone member. The upper part of the Chesterfield Range Group, here named the Monroe Canyon Limestone is about 925 ft. thick and contains a lower massive member and a medial medium-bedded member, and an upper cherty member. The range stretches northwest from Soda Springs, Idaho. It is an eastern dipping block of Paleozoic strata irregularly overlapped by the Tertiary Salt Lake Fm.

Environment/lithology: shelly/skeletal, cherty/siliceous limestone

Primary reference: J. T. Dutro and W. J. Sando. 1963. New Mississippian Formations and Faunal Zones in Chesterfield Range, Portneuf Quadrangle Southeast Idaho. Bulletin of the American Association of Petroleum Geologists 47(11):1963-1986 [T. Olszewski/M. Gibson]more details

PaleoDB collection 12901: authorized by Tom Olszewski, entered by Melissa Gibson on 02.01.2002

Creative Commons license: CC BY (attribution)