Silurian System

Type section and use of name: The Kenneth Limestone Member was named as a formation by Cumings and Shrock (1927, p. 77) for about 30 feet (9 m) of light-colored dense to fine-grained bedded to massive cherry lime-stone that is typically exposed in an abandoned France Stone Co. quarry near Kenneth, Cass County, Ind. Pinsak and Shaver (1964, p. 81) thought that according to Cumings and Shrock (1928a, p. 134) the Kenneth type section is in the large composite quarry in the center of see. 30 and in the N2SW¼ sec. 30, T. 27 N., R. 1 E. Some question remains, however, about the location of the type section because Cumings and Shrock (1928a, p. 177) also mentioned quarrying in the adjoining section (sec. 25, T. 27 N., R. 1 W.) also, because still another large quarry, once operated by the same company that operated the composite quarry, is in the SW¼SE¼ sec. 30. The Kenneth in this area both overlies and appears to be interlensed with laminated dolomitic limestone assigned to the Kokomo Limestone Member (Wabash Formation).

The rank of the Kenneth was changed to that of member by Pinsak and Shaver (1964, p. 51) and assigned to the Salina Formation. The Kenneth was later assigned to the Wabash Formation when the latter unit, together with the Pleasant Mills Formation, was assigned to the elevated-in-rank Salina Group (Droste and Shaver, 1982, p. 21)

Description: Besides the Kenneth lithologic features noted above, the unit appears to be coarsely mottled in places (in its fine-grained facies); in some other places it consists of whitish to pinkish granular (even starry) limestone that commonly is abundantly fossiliferous. This facies includes coquina of brachiopods (for example, Coelospira congregata and pentamerid brachiopods) and ranges in its character to reef-framework rock (dolomitized in places) complete with abundant corals of the Halysites and Coenites types. (See Tollefson, 1979, p. 41-47; Pinsak and Shaver, 1964, p. 81; and Shaver and Sunderman, 1983, p. 177-178; the latter two sources record the reefy facies.)

The Kenneth has very limited distribution because of the definitive intraformational relations within the Wabash (Droste and Shaver, 1982, p. 23). Its basic character as cherry dolomitic limestone and its high stratigraphic position hardly distinguish the Kenneth from the similar Liston Creek; the Kenneth is to be distinguished, therefore, only where Silurian rocks of its type are underlain by the distinctively laminated Kokomo member. The lower Kenneth contact appears to be fairly sharp in places but involves gradational lithology with the Kokomo in other places (as recorded in two of the sources given above). The sand grains and other clastic sediments found in many places associated with this contact are not evidence of intra-Silurian unconformity rather, of pre-Middle Devonian karst. The upper Kenneth contact everywhere coincides with the pre-Middle Devonian unconformity. The Kenneth is hardly known outside the type county (Cass), although older reports of its occurrence in Howard County above the Kokomo are surely correct. It is now known in Miami County (Ault and Carr, 1983, p. 24; Shaver and Sunderman, 1983, p. 177-178), but its occurrence there was said to be of the Liston Creek in older literature. As a matter of similar confusion, older reports of the Kenneth in Carroll County have proved to refer to other rocks, but a modern report Indiana University Paleontology Seminar, 1980) has again identified probable Kenneth rocks in Carroll County.

The Kenneth ranges in thickness from an erosional zero to an average of 25 to 30 feet (7.6 to 9.2 m) and a maximum of about 45 feet (14 m) where this unit is beneath Devonian cover.

Correlation: Within the Wabash, the Kenneth correlates with an upper part of the Liston Creek, this being a matter of coextension, but the highest Liston Creek rocks in Indiana, both on the northern outcrop and in the southwestern subsurface, are possibly slightly younger than the Kenneth. The Kenneth, therefore, correlates, as do upper Liston Creek rocks, with the upper part of the Bailey Limestone of the Illinois Basin. Further, the Kenneth is known to have rare kinds of pentamerid brachiopods that in Illinois and Indiana are known only in high stratigraphic positions, but the collective conodont and ostracod evidence indicates a very late Silurian age (Pridolian in European terms late Cayugan in American terms). The ostracod fauna, abundantly represented by Dizygopleura hallii and Thlipsurella parva, and associated fossils suggest even a post-Salina age and correlation with highest Silurian rocks of New York and other Appalachian Basin states, but the conodonts have not yet been definitive between late-Salina depositional time or post-Salina (Bass Islands Group) depositional time with respect to the Salina section of the Michigan Basin parts of northern Indiana, northwestern Ohio, and southern Michigan. (See Pollock and Rexroad, 1973, p. 79-81; Tollefson, 1979, p. 106-110; and Shaver and others, 1971.)