The Wheaton Consolidated oil field is in Union and Barton townships of Gibson County, Indiana. The field has produced oil since the 1920s from a sandstone reservoir referred to as the "Jackson Sand," which is equivalent to the Big Clifty Formation of surface terminology. The Big Clifty Formation is part of the Stephensport Group, and is Chesterian or Late Mississippian in age.

Within the field area the Big Clifty Formation can be mapped between the underlying Barlow Limestone and overlying Golconda Limestone. The lower contact appears to be sharp over the field area. The upper contact of the Big Clifty intergrades with at least one tongue of Golconda which pinches out into the Big Clifty.

The Big Clifty Formation includes sandstone, shale, and mudstone with minor amounts of sandy limestone. A typical sequence from top to bottom includes: black shale; thin red mudstone; gray shale; silty limestone; interbedded gray shale and very fine-grained, white, sandstone; well sorted, fine-grained, white, sandstone; and thin gray shale. The percentage of sandstone within the Big Clifty Formation varies significantly.

The thickness of the Big Clifty Formation ranges from 64 to 89 ft (19.5 to 27 m). The unit dips to the

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southwest and is 940 ft (287 m) below the surface within the northwest part of the study area and 1,330 ft (405 m) below the surface in the southwest part of the study area.

The areas containing high concentrations of sandstone form two elongated trends within the study area. The sandstone trends strike N55°E, and trend axes lie approximately 1 mi (1.6 km) apart. The sandstone bodies are approximately 3/4 mi (1.2 km) across and 5 mi (8 km) long, and range in thickness from 3 to 40 ft (~ 1 to 12 m).

The sandstone bodies may represent shallow marine offshore bar or strandline deposits.

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