This report presents stratigraphic data and interpretations pertaining to the origin of a continental shelf-ocean basin sedimentary complex developed during Lower Cretaceous time in northern Coahuila, Mexico. This shelf was developed within a carbonate depositional regime and provides a specific descriptive example which should be useful in the development of a comprehensive process-response model of shelf origin.
Northern Coahuila, Mexico, lies below the great northern arc of the Rio Grande near the middle of the border between Texas and Mexico. It is the larger Mexican counterpart of the Big Bend area of Texas which joins it on the west. The area mapped by geologists of Petroleos Mexicanos during the course of this investigation covers about 16,000 square miles and measures at a maximum about 160 miles east-west and 120 miles north-south. Lower Cretaceous outcrops in the Serran�a del Burro and southern part of the Sierra del Carmen were studied by the author.