New Mexico Geological Society
Fall Field Conference Guidebook - 25
Ghost Ranch


Charles T. Siemers, Lee A. Woodward and Jonathan F. Callender, eds, 1974, 404 pages.

The New Mexico Geological Society was founded in 1947. The year 1974, however, will long be remembered as the"Silver Anniversary" of the Geological Society in commemoration of the 25th consecutive field conference. The first day road log is from Ghost Ranch to Cuba and Nacimiento Mine. The route begins near the south end of the Chama Basin where excellently exposed Permian through Jurassic strata are seen. Then we cross the south end of the Gallina-Archuleta arch which separates the shallow Chama Basin from the structurally deeper San Juan Basin and enter the San Juan Basin. Then turning southeast we approach the eastern edge of the San Juan Basin and the western part of the Nacimiento uplift. Leaving Cuba we see progressively steeper-dipping Cretaceous rocks and upon reaching the Mesaverde outcrop the section is overturned (the beds dip toward the east). As we continue eastward, the Jurassic section is also inverted and we then cross the Nacimiento fault. East of the fault, the Triassic Chinle Formation is rightside-up. The second day road log is from Coyote Junction of US-84 and NM-96 to Abiquiu, El Rito, Petaca, Tres Piedras, Hopewell Lake, Chama Basin, and return to Ghost Ranch. The highlights of this route will be Tertiary rocks of the Rio Grande rift, Precambrian rocks and pegmatite deposits of the Brazos uplift, and Jurassic-Cretaceous stratigraphy of the Chama Basin. The third day road log is from Junction US-84 and El Rito turnoff to Espanola, Valle Grande, San Ysidro, and Bernalillo. Highlights of this trip will be exposures of Tertiary strata of the Rio Grande rift, volcanic rocks and structures of the Jemez Mountains, geothermal energy, and Mississippian and Pennsylvanian stratigraphy.

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