In 1937 the writer defined the Lodo formation exposed along the west side of the San Joaquin Valley, California, as a shale unit with an included sandstone member (Cantua sandstone). The formation is stratigraphically above the Moreno shale (Upper Cretaceous) and below the Domengine sandstone (middle Eocene).

The Domengine in that paper erroneously was considered to be the "Domijean sands" of F. M. Anderson (1905). It included the "Tejon" of Anderson and Pack (1915), or the restricted Domengine of Clark and the underlying sandstone referred by him to the Meganos. However, a critical reading of the original definition of Anderson's "Domijean sands" shows that it included all strata from the base of the Cantua sandstone member to the base of the Kreyenhagen shale of later workers. It is, therefore, an unsuitable cartographic term. The Domengine as redefined by Clark is a well defined mappable unit.

The name Yokut is here proposed for the sandstone unit that lies between the top of the Lodo shale and the pebble bed at the base of the Domengine as redefined by Clark. The Yokut is overlapped by the Domengine at the axis of Coalinga anticline on the south, and approximately one mile northwest of Tumey Gulch on the north. The lower contact of the Yokut is gradational with the underlying carbonaceous sandy siltstone in the upper part of the Lodo.

The type locality of the Yokut sandstone is near the west boundary of the SE. ¼, Sec. 29, T. 18 S., R. 15 E., M.D.B., in Domengine Creek where the formation is 45 feet thick. A maximum thickness of 305 feet was observed between Salt Creek and Martinez Creek.

Yokuts is the name of an Indian tribe who inhabited the San Joaquin Valley.