New Mexico Geological Society
Fall Field Conference Guidebook - 35
Rio Grande Rift: Northern New Mexico

W. Scott Baldridge, Patricia W. Dickerson, Robert E. Riecker and Jiri Zidek, eds, 1984, 379 pages.

Welcome to the Thirty-fifth Field Conference of the New Mexico Geological Society, cosponsored this year by the Los Alamos National Laboratory. The theme is the Rio Grande rift. The first-day road log is from Taos to Embudo, Dixon, Penasco, Vadito, Tres Ritos, Holman Hill, and back to Taos via U.S. Hill and Talpa. This route circles the Picuris Range, an east trending spur on the west side of the Sangre de Cristo Mountains. It forms part of the division between the San Luis Valley and Espanola Basin segments of the Rio Grande rift. The second-day road log is from Taos to Hondo Canyon, Questa, Red River, Amalia, and back to Taos. This tours focuses on the complex geology of the Sangre de Cristo Mountains, a narrow and rugged mountain uplift that extends for more than 300 km north and northwestward from Glorieta Pass east of Santa Fe, New Mexico to Poncha Pass southwest of Salida, Colorado. The guide is organized in three segments that permit examination of progressively higher structural and stratigraphic levels in the Taos Range. The third-day road log sets out from Taos and travels to Tres Piedras, Tusas Spring Canyon, Tres Piedras, Las Tablas, Petaca, La Madera, and Ojo Caliente. This tour will cross the Rio Grande rift from Taos to Tres Piedras. At Tres Piedras the route leaves the Taos Plateau and enters the Tusas Mountains where Precambrian rocks are partially covered by primarily Tertiary sedimentary deposits of the El Rito and Los Pinos formations. Throughout the Tusas Mountains there are also exposures of pre-rift volcanic rocks of intermediate composition, similar to those of the San Juan and Latir volcanic fields.

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