The Sierra de Jimulco is situated in the southwestern corner of the State of Coahuila, about 12 miles southeast of the city of Torreon. From the Coahuila-Durango State line along Rio Aguanaval the range extends eastward for more than 50 miles. It is 11 to 18 miles wide and covers an area of about 800 square miles.
From the broad plain of Viesca the Sierra de Jimulco rises to the south in a rugged and forbidding mountain mass. The highest peak is the Picacho de Jimulco in the southwest corner of the range, rising to about 7000 feet elevation with a relief of more than 2000 feet above the valley of Rio Aguanaval (figure 3). Dissecting the range are a number of broad, flat valleys from which the bordering rock ridges ascend precipitously. These valleys make it possible to reach the central part of the mountain area by automobile . . .