In planning for a modern geologic map of the State (scale 1:250,000), a bibliography of published and unpublished geologic maps of areas in Texas was compiled under the direction of Virgil E. Barnes, Director of the Geologic Atlas Project of the Bureau of Economic Geology. The area of those areal geologic maps with a scale of 1:250,000 or larger is outlined on the accompanying index map. The index map also shows the 1:250,000 scale Army Map Service 1 deg X 2 deg quadrangles, which serve as a base for the new Texas Geologic Atlas (see inset).

This index updates the "Geologic Map Index of Texas" compiled by Leona Boardman for the United States Geological Survey for the period up to 1951 and also incorporates unpublished geologic maps in theses and dissertations. In some parts of the State, areal geologic maps are numerous and overlapping, so a system of color overlays is used to distinguish them. Black designates unpublished maps. Three other colors delineate maps grouped by the date of publication. The oldest group, comprising 93 items, was published from 1891-1936 (blue); the second group of 92 items was published from 1937-1950 (green); the youngest group, containing 81 items, was published from 1951-1961 (red). For central Texas, where map density is high, two enlarged insets are included.

The following bibliography includes published and unpublished maps at a scale of 1:250,000 or larger, which are outlined and numbered on the accompanying index map, and also maps at a scale smaller than 1:250,000. These small-scale maps are not shown on the index map. The unpublished maps are from theses and dissertations, and the bibliography shows their repository. The bibliography includes indexes by author, by county, by 1 deg X 2 deg AMS quadrangle, and by region, the last including only the small-scale geologic maps that cover large areas. The small-scale maps (smaller than 1:250,000), comprising 93 items (nos. 267-359), are listed in the bibliography.