Mississippian and Pennsylvanian strata of the Leonard Ranch area do not correlate nicely with the Mid-Continent standard section, nor can they be forced into current published classifications. Study of the field relationships, petrography, and paleontology has shown that some lithic units are discontinuous but that the Marble Falls formation can be usefully subdivided into the following members: Lower limestone, Middle limestone and shale, and Upper limestone. Physical and faunal evidence do not support the interpretation of an unconformity between the Barnett and Marble Falls formations, nor does the formation boundary coincide with the systemic boundary. Twenty-nine species of conodonts, twenty-three species of brachiopods, seven gastropods, two cephalopods, and two corals are described from the Chappel, Barnett, Marble Falls, and Smithwick formations. Possibilities for zonation are presented. ; Geological Sciences