New Mexico Geological Society
Fall Field Conference Guidebook - 20
The Border Region

Diego A. Cordoba, Sherman A. Wengerd and John Shomaker, eds., 1969, 228 pages.

On behalf of the Executive Committee and members of the New Mexico Geological Society, Inc., I welcome you to our Twentieth Annual Field Conference. The society is indeed honored and fortunate to be able to sponsor this tour in our neighboring State of Chihuahua. The first day road log is from Ciudad Juarez to Nuevo Casas Grandes, via Sierra de Juarez, Sierra Boca Grande, Ascencion, and Janos. Much of this trip is across the broad bolson plains of northwestern Chihuahua where we will learn about the geologic histories of these basins and their potentially important water supplies. The traverse is punctuated by a stop at the southern end of the Juarez Mountains to visit some Lower Cretaceous reefs and at the pass of Sierra Boca Grande where Permian rocks are exposed. The second day road log is from Nuevo Casas Grandes to Chihuahua, via Paquime, San Buenaventura, Mina la Mojina, and Sueco Junction. Geologic highlights include an extensive and variable sequence of volcanic rocks exposed in roadcuts in Sierra de las Tunas. At the Sierra de la Mojina stop we will see a spectacular section of Lower Cretaceous carbonates, an operating manganese mill, and an abandoned silver mine. The third day road log is from Chihuahua to Ciudad Juarez, via Encinillas Basin, Sueco Junction, Villa Ahumada and Sierra del Presidio. Highlighs include "arm waving" at Jurassic and Cretaceous sediments in the Sierra de la Alcaparra, the anticlinal Sierra de Samalayuca with its core of metamorphosed sediments, and highly fossiliferous Lower Cretaceous reef limestones at the north end of Sierra del Presidio.

Papers from this guidebook are available for download from the NMGS website.