The Coahuila Coal District (Sabinas area) is located in the east-central part of the state of Coahuila between 26°45′ and 27°70′N, and 100°15′ and 102°00′W in the Coahuila Basin and Range physiographic province. The area covers approximately 30,000 km2 , and the existence of coal has been established in subbasins of widely varying dimensions: La Esperanzas, Sabinas, Saltillito-Lampacitos, San Salvador, Castaños, Las Adjuntas, Monclova, and San Patricio (Fig. 1). The Río Escondido coal basin, to the northeast, is discussed in Chapter 9 of this volume.
The region is one of extensive plains and bolsons within which the coal-bearing subbasins occupy synclinal structures separated by steeply dipping anticlinal limestone ranges. Climate and vegetation are semidesert; as typical for northern Mexico, seasonal temperature differences are pronounced. The dentritic, generally south-southeast drainage is controlled by Ríos Alamo, Salado, Monclova, and San Juan, draining into the southeastflowing Rio Sabinas.