Exploratory geology of a part of southwestern Trans-Pecos Texas
Department
Description
The present bulletin completes the work of preliminary exploration
of the mountain region of Trans-Pecos Texas
begun twenty years since by the University of Texas
Mineral Survey and completed by the University of Texas
Bureau of Economic Geology. The region treated in the
present paper is bounded on the north by the line of the
Texas & Pacific Railway, on the west by the Malone Mountains,
on the southwest by the Rio Grande, and on the east
practically by the line 104° 30' west longitude. The field
work was done at the rate of about thirty-five square miles
per day. Much of the mapping was schematic and thicknesses
of rock sections were estimated. The structure
proved to be complicated and only the main structural features
were determined. The main new results of the present
work are four :
1. The determination of the probable Permian age of
the gypsum beds of the Malone Mountains.
2. The classification in a general way of the Comanchean
sediments, a work very greatly aided by the fossil determinations
of Professor W. M. Winton.
3. The discovery of complicated structure in the
Quitman and Eagle mountains, with overturning and overthrusting
of strata.
4. The assignment of the epoch of this intense deformation
to Cretaceous time later than Taylor and before the
final disappearance of Cretaceous dinosaurs.