The area described in this report lies in southern Coahuila in the central part of the Parras Basin. It comprises about 175 square miles of hilly country, roughly triangular in outline, along the eastern side of the Laguna de Mayrán. The Central Mexican Railroad (Saltillo to Torreón) skirts the northern border of the hills. Their western limit is approximately at a line drawn from the station of Ceres, on this railroad, southwest to Hacienda La Bola at the southern end of the Laguna de Mayrán. They are separated from the high ranges of the Sierra de Parras and Sierra de La Peña on the south by a plain several miles wide and extend eastward parallel to the mountains for many miles. The area mapped will be referred to as El Pozo-Boquillas area, after the two principal settlements.
The writer wishes to express his . . .