Coahuila lies in the broad northern end of Mexico, immediately east of
the center of the continental mass. The mountains of Coahuila, which
are part of the Rocky Mountain-Sierra Madre Oriental Axis, extend in a
north-south direction and divide the lower lands into two areas, a
larger one, a part of the Central Plateau, to the westward and a
smaller one, a part of the Gulf Coastal Plain, to the northeastward.
Most of the mountains of Coahuila do not exceed 6000 feet in elevation.
A few peaks such as in the Sierra del Carmen, Sierra del Pino, Sierra
de la Madera, Sierra Encarnacion, and Sierra de Guadalupe, are more
than 9000 feet high, and some more than 10,000 feet in elevation occur
near the southeastern border of the State in the Sierra Madre Oriental.
The Gulf Coastal Plain of northeastern Coahuila ranges from 700 feet to
1800 feet. The desert plains of the Mesa del Norte to the west of the
Sierra Madre Oriental Axis are higher, more rugged, and more dissected
than those of the Coastal Plain and are marked by scattered desert
ranges, buttes, low hills, and knobs.
Most of Coahuila is arid. Rainfall is moderate on the Coastal Plain and
is low west of the central mountains. Baker (1956:128-132) and Muller
(1947:35-38) give good summary discussions of the topography and
climate of Coahuila, and the reader is referred to these for further
details.