Pennsylvanian System
Type locality and history of name: The Brazil Formation as originally named by Fuller and Ashley (1902, p. 2) for Brazil, Clay County, Ind., included the rocks in the interval between the top of the Mansfield Sandstone and the bottom of the Petersburg Coal (Springfield Coal Member of present usage). Cumings (1922, p. 525) amended the Brazil Formation to include only the rocks in the interval between the base of the Lower Block Coal Member and the unconformity above what was then called Coal II. Hutchison (1976, p. 22-23) further amended the Brazil to include only those rocks between the top of the Minshall Coal Member and the base of the Lower Block Coal Member
Description: In the Brazil area the formation consists of shale, sandstone, underclay, and coal and ranges from 40 to 90 feet (12 to 27 m) in thickness (Hutchison, 1960, p. 13). The Brazil Formation consists in ascending order of the Lower Block, Upper Block, and Minshall Coal Members and other rocks unnamed to member. In places a thin coalbed referred to as the rider of the Upper Block Coal Member is present in the interval between the Upper Block and the Minshall Coal Members.
lrregularity, both in thickness and in persistence of recognizable beds, is characteristic of the Brazil Formation in much of its area of outcrop from Warren County on the north (Hutchison, 1961) to Spencer County (Hutchison, 1959) on the Ohio River. North of southern Parke County, for example, the Lower Block coal is absent or untraceable, so that it is nearly impossible to separate the Brazil and Mansfield Formations in southern Indiana, in Daviess (Hutchison, 1971a), Dubois (Hutchison, 1964), and Spencer (Hutchison, 1959) Counties, coalbeds believed to be equivalent to the block coals are present over most of the area but are difficult to distinguish from upper Mansfield coals. Numerous drill holes penetrate the Brazil in the subsurface in Indiana, but detailed information on the character of the coals and other marker beds is wanting in extreme western and southwestern Indiana because of lack of coring or detailed mapping.
Correlation: The rocks assigned to the Brazil Formation in Indiana are equivalent to the upper and lower parts respectively of the Abbott and Spoon Formations of Illinois and part of the Tradewater Formation in western Kentucky (Kosanke and others, 1960, pl. 1).
The Brazil Formation was assigned by Wanless (1962) to the upper part of what was then called the Pottsvillian Series in the Appalachian area, but later it was assigned to the Atokan Series in the North American Pennsylvanian standard by Shaver and Smith (1974, p. 17-20), Shaver (1984), and Shaver and others (1985). Much of the basis for the Atokan assignment is the occurrence of a species of the fusulinid genus Fusulinella (identified by M. L. Thompson) in an unnamed limestone between the Lower and Upper Block coals in Clay County, Ind. Its stratigraphic position is below the lowest occurrence in Indiana of the lower type Desmoinesian indicator Fusulinella iowaensis and above the known occurrences of the Morrowan indicators that are discussed in the articles on the Lead Creek Limestone Member and its Ferdinand and Fulda Beds.