9

LETTER OF TRANSMITTAL.

DEPARTMENT OF THE INTERIOR,
UNITED STATES GEOLOGICAL SURVEY, Washington, D. C., May 14, 1899.

SIR:

I submit herewith for publication a manuscript by Mr. T. Wayland Vaughan, entitled Reconnaissance in the Rio Grande Coal Fields of Texas. This paper treats of two areas, both of which, in addition to the economic considerations, are of scientific interest, inasmuch as they give interesting types of the geology of the localities studied.

The first of the areas embraces that portion of the Lower Rio Grande region lying between Del Rio and Laredo, and treats of a section of the Cretaceous and Tertiary formations and of the relations of the one to the other. This section has been an object of interest for many years, and, as shown in the literature cited by Mr. Vaughan, has been visited by many geologists. As the region is a transition ground between the phases of these formations hitherto considered peculiar to the Rocky Mountain and the Atlantic Coastal plains, respectively, such a section must necessarily throw some light upon the relations of the formations, including the age position of those hitherto ascribed to the Laramie epoch. Mr. Vaughan could hardly be expected to solve completely all the problems of the region in the short period of time during which he was permitted to examine it, but his paper will be a valuable contribution to a progressive series of researches which have been made in that territory.

The second paper treats of the San Carlos coal field in Trans-Pecos Texas. This paper, too, is of great scientific interest, inasmuch as it gives a detailed section of the Cretaceous beds of the Vieja Mountains of the Trans-Pecos region, and also throws light upon the occurrence of interesting volcanic rocks.

Mr. Vaughan has treated the, economic features more briefly than he would have done if the determination of the stratigraphic position of these coals had not been the principal object of these preliminary reconnaissances.

Very respectfully,

ROBT. T. HILL, Geologist.

Hon. CHARLES D. WALCOTT, Director United State Geological Survey.