The Pennsylvanian System, Socorro region, New Mexico--Stratigraphy, petrology, depositional environments
— William T. Siemers

Socorro, the principal settlement in west-central New Mexico, is located about 120 km south of Albuquerque. Pennsylvanian rocks in this area crop out in widely separated, isolated, fault-block mountains within and along the Rio Grande rift. Studies of Pennsylvanian rocks in west-central New Mexico have been chiefly reconnaissance efforts that have produced a general model of Pennsylvanian stratigraphy and sedimentation (reviewed in Kottlowski, 1960). More recent studies (Martin, 1971; Myers, 1973; Siemers, 1978) have focused on strati- graphic interpretations, petrography, and depositional systems of the Pennsylvanian deposits. Regional and local aspects of the Pennsylva- nian rocks, including: (1) stratigraphy, biostratigraphy, and nomencla- ture; (2) thickness estimates; (3) petrography; and (4) depositional framework, are reviewed here.