M. E. Hopkins and J. A. Simon
The Missourian Series of the Pennsylvanian System (Keyes, 1893, p. 114-116; Moore, 1931) is named for the state of Missouri, where strata containing much limestone and a very little coal overlie the Desmoinesian rocks.
In Illinois the Missourian includes rocks from the top of the Trivoli Sandstone Member up to a position a few feet below the coal that lies below the Shumway Limestone Member (Willman et al., 1967). It therefore includes the upper part of the Modesto Formation, all of the Bond Formation, and about half of the Mattoon Formation, all in the McLeansboro Group (fig. P-2).
Where fusulinids are present, as they are in many units in Illinois, the Missourian is characterized by earlier forms of the genus Triticites, which is the sub-genus Kansanella of Thompson. Floral zones are not as well defined in the Illinois Basin and the Midcontinent area, where the Missourian and overlying Virgilian together constitute Zones 11 and 12 (zone of Odontopteris sp.) (Read and Mamay, 1964). Delineation of the ranges of spore taxa in the Missourian and Virgilian Series has not been determined with the same degree of accuracy as is true for the remainder of the Pennsylvanian because the stratigraphic relation of many of the coals has not been worked out in detail. Small spores of ferns and seed ferns, many less than 30 microns in diameter, are prolific in most of the Missourian and Virgilian coals. The taxa are classified as Punctatisporites minutus, Laevigatosporites minutus, and species of Cyclogranisporites and Apiculatisporis. Endosporites is very abundant in many of the coals.
KEYES, C. R., 1893, Geological formations of Iowa: Iowa Geological Survey, v. 1, p. 11-144.
MOORE, R. C., 1931, Pennsylvanian cycles in the northern Midcontinent region: Illinois State Geological Survey Bulletin 60, p. 247-257.
READ, C. B., and S. H. MAMAY, 1964, Upper Paleozoic floral zones and floral provinces of the United States: USGS Professional Paper 454-K, p. K1-K35.
WILLMAN, H. B., et al., 1967, Geologic map of Illinois: Illinois State Geological Survey.
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