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Kansas Geological Survey, Current Research in Earth Sciences, Bulletin 253, part 1
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The Riverton Formation and Riverton Coal Bed

The Riverton coal is an important coal in eastern Kansas, western Missouri, and northeastern Oklahoma, but geologists working in the various states have not always agreed concerning its stratigraphic position in relation to the Atokan-Desmoinesian boundary. Pierce and Courtier (1937) named the Riverton coal for a thin coal exposed in a sinkhole in Cherokee County, Kansas. Abernathy (1937) used the name Riverton Cyclothem Formation for the lowermost Pennsylvanian rocks in the area and included the Riverton coal at the top. Searight et al. (1953) in describing the Riverton Formation included the Desmoinesian rocks below the Riverton coal and Warner Sandstone. The Desmoinesian Series, which was defined in Iowa, was to include all the lower Pennsylvanian rocks (Keyes, 1896). It is now known that the lower part of the Desmoinesian in Iowa includes Atokan and Morrowan rocks (Ravn et al., 1984; Ravn, 1986). The upper part of the Riverton Formation contains one to several coals in addition to the Riverton coal. Kansas continues to recognize the Riverton coal as a bed in the Krebs Formation of the Cherokee Group (Jewett et al., 1968).

Searight et al. (1953), Searight (1955), and Howe (1956) considered the Riverton Formation in Missouri to be Desmoinesian in age, but they placed the Riverton coal and the rest of the Krebs Formation below the Seville Limestone member, which in Illinois is at the Atokan-Desmoinesian boundary. Searight and Howe (1961) transferred the Riverton Formation from the Desmoinesian to the Atokan. Atokan fusulinids were found in a limestone in the Riverton Formation in southwestern Missouri (M. L. Thompson, 1953), and Searight (1959) suggested that a limestone in the upper part of the Riverton Formation in the Forest City basin in Missouri indicated the presence of Atokan rocks. Also a sinkhole in southwestern Missouri contains Atokan conodonts in rocks thought to belong to the Riverton Formation (T. L. Thompson, 1979; Lambert and Thompson, 1990). T. L. Thompson (1979) considered the entire formation Atokan in age.

Wanless (1956) correlated the Riverton Formation in Missouri with the Caseyville Formation in the Illinois basin, and Kosanke et al. (1960) correlated it with a position below the Seville Limestone in Illinois. The Caseyville is now considered Morrowan in age, and the interval below the Seville Limestone is Atokan (Hopkins and Simon, 1975; Peppers, 1996). A coal bed in the upper part of what the Missouri Geological Survey considers the Riverton Formation in a strip mine in Barton County, Missouri, yielded a Desmoinesian spore assemblage (Peppers et al., 1993). In addition, a coal at the top of the Riverton Formation in the subsurface of the Forest City basin in Missouri contains a Desmoinesian spore assemblage (Peppers et al., 1993). Peppers (1996) correlated, based on palynology, the Riverton coal with the early Desmoinesian Lewisport coal bed in the Illinois basin.

In Oklahoma the McAlester Formation, which contains the Riverton coal, is considered Desmoinesian in age (Moore, 1948; Fay et al., 1979; Suneson and Hemish, 1994). Branson (1962) correlated the Riverton coal with the Upper Hartshorne coal bed, but the McAlester Formation overlies the Hartshorne Formation. Wilson (1970) studied palynology of the Upper and Lower Hartshorne coals near Wilburton, Oklahoma, and he concluded that the coals are Desmoinesian in age. Peppers came to the same conclusion after examining a sample of the Hartshorne coal from sec. 14, T. 14 N., R. 19 E., in Haskell County, Oklahoma (unpublished data, 1992).

Morgan (1955) reported on the palynology of the Riverton coal at its type section in NE sec. 9, T. 32 S., R. 25 E. [lat. 37° 16' 39", long. 94° 38' 10"], Cherokee County, Kansas. He concluded that the coal is older than the McAlester coal and younger than the Hartshorne coal. The sample of the Riverton coal from the same locality that Peppers examined contains a poorly preserved spore assemblage, but the limited data support an early Desmoinesian age. Wilson (1979a) also compared spore genera present in a sample of the Riverton coal in Cherokee County with the shale samples from a well in Cherokee County. Although many of the spores in the shale were recycled or have a long stratigraphic range, he concluded that the shale is probably part of the McAlester Formation. Rosowitz (1982) correlated, by use of spores, the Riverton coal from several cores in Cherokee and Crawford counties, Kansas, with the lower Hartshorne coal of Oklahoma.

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Kansas Geological Survey
Web version Aug. 16, 2007