Dry Branch quadrangle is in the Edwards Plateau province southwest of the Llano region. It is near the margin of the plateau, and Johnson Creek and some of its tributaries, such as Dry Branch, Falls Branch, Fessington Branch, and Welch Branch, have cut into the plateau in the southern part of the quadrangle.

The Hood Spring quadrangle, in the central part of Brewster County, Texas, contains a segment of the southeast rim of the Marathon basin. It includes a part of the complexly folded and faulted Paleozoic rocks that occur in the center of the Marathon basin and also includes Cretaceous rocks exposed in the Maravillas scarp. This scarp has three stratigraphically separate cuestas that are formed by southeastward gently dipping beds. The southwestern corner of the quadrangle contains a faulted and folded segment of the Santiago Mountain range.

Preparation of a desk-side reference manual of Cretaceous foraminifera was undertaken as a project of the Bureau of Economic Geology, where I was a staff member during the summers of 1945 to 1947 and during July of 1951. Although the Handbook is intended primarily for the advanced college-level student and routine commercial laboratory micropaleontologist, it should be useful as well to the specialist. The accuracy of a compilation of this kind is never greater than that of the sources from which it is taken, and errors of transcription and interpretation are unavoidable.