Mississippian System

Type locality and history of name in Indiana: The name Bethel Sandstone was first used by Butts (1917, p. 63-64) in describing exposures of thick-bedded coarse-grained sandstone and slabby sandstone 10 to 40 feet (3 to 12 m) thick in the vicinity of Bethel School, near Marion, Crittenden County, Ky. The term has become widely adopted throughout the Illinois Basin and is now a unit in the standard Chesterian section (Willman and others, 1975, p. 153-154).

When first recognized in Indiana, this unit was identified (Malott, 1919, p. 9) with the Sample Sandstone Member of the Gasper Oolite (Limestone) of Butts (1917, p. 70-73). When the formation was later proved to be somewhat older, it was given the name Mooretown Sandstone for a village in Lawrence County, Ind. (Cumings, 1922, p. 515). The Bethel identification was established by Swann and Atherton (1948), among others, and the present form of the name was adopted in recognition of the mixed lithologic character of the unit (Gray and others, 1957, p. 6, pl. 2).

Description: In Indiana the Bethel Formation includes gray clayey shale, ripple-bedded fine-grained sandstone, thin beds of coal, and in places underclay and non stratified sandstone that contain abundant rootlet compressions. It ranges from 1 to 42 feet (0.3 to 13 m) in thickness (Sullivan, 1972, p. 14), and on the outcrop it generally forms covered slopes. The formation crops out from Putnam County southward to the Ohio River and can he recognized in the subsurface from Parke County southwestward. Over most of this area it conformably overlies the Paoli Limestone of surface nomenclature and the Renault Formation of the subsurface. The Bethel Formation is overlain conformably by the Beaver Bend Limestone or disconformably by the Mansfield Formation (Morrowan).

In a narrow linear area nearly 120 miles (200 km) long and mostly in the subsurface, the Beaver Bend Limestone is depositionally missing (Sullivan, 1972, p.12-13) and the top of the Bethel Formation cannot be determined. This area is called the West Baden clastic belt. (See under "Elwren Formation.") Where the clastic belt reaches the outcrop in Greene and Owen Counties several sections described by Malott (1952, p. 45-49) show clastic rocks of the West Baden Group resting disconformably on the Levias Member of the Ste. Genevieve Limestone. In different areas, therefore, the same horizon, the base of the Bethel Formation and the base of the West Baden Group, is conformable where the Bethel can be recognized as a discrete formation and disconformable where it cannot.

Scattered deposits of poorly consolidated varicolored sand overlying the Salem and St. Louis Limestones in upland areas of Washington, Clark, Floyd, and Harrison Counties were designated the Ohio River Formation by Ashley and Kindle (1903, p. 70). Wayne (1960) restudied these deposits and assigned them a Paleocene age, but equivalent deposits in Kentucky, called the Tip Top Sand by Sutton (1931), have been considered by others to be Chesterian in age (Ray, Butler, and Denny, 1946 Swadley, 1963). A petrologic study coordinated by Paul E. Potter (Sedimentation Seminar, 1969) demonstrated that the Tip Top Sand and the Ohio River Formation are remnants of an extensive channel filling that belongs to the Bethel Formation. In these scattered outliers the rocks have been decemented as a result of prolonged exposure. Consolidation has further been destroyed by physical lowering of the sand bodies as the underlying limestone was dissolved, and this process was itself expedited by the permeability of the sand bodies themselves.

Correlation: Rocks that were formerly referred to the middle part of the Paint Creek Formation in the Illinois standard section are now assigned to the Bethel Formation, and use of the name Paint Creek (with group rank) is restricted to western Illinois (Willman and others, 1975, p. 152-154). The name Morretown remains in use for equivalent strata in Kentucky (for example, Amos, 1972).