The field work on which this report is based was done during October and November, 1936. It consisted of the mapping by reconnaissance methods of the areas of outcrop of the formations over as large a portion of the county as possible, followed by the detailed mapping of the area west of Elkhart with the plane table. This work was supplemented by coring with hand tools.

A mineral resource survey of Texas has been started by the Works Progress Administration, with the Bureau of Economic Geology of The University of Texas acting as sponsor. The purpose of the survey is to assemble information and make it available to the public. Through a separate project, sponsored by the State Planning Board, the results of the survey, as they are received in Austin, are being assembled for publication.