Maps

This report presents a 1:24,000-scale geologic map, cross sections, and descriptive and interpretative text for the Poncha Pass area in central Colorado. The map area is irregular in shape, covering all of one 7 ½' quadrangle (Poncha Pass) and parts of five others (Mount Ouray, Maysville, Salida West, Salida East, and Wellsville). The map boundaries were drawn to cover all of the “Poncha...

Geophysical investigations of Mountain Pass and vicinity were begun as part of an effort to study regional crustal structures as an aid to understanding the geologic framework and mineral resources of the eastern Mojave Desert. The study area encompasses Mountain Pass, host to one of the world’s largest rare earth element carbonatite deposits. The deposit is found along a north-northwest...

The U.S. Geological Survey, in cooperation with the Albuquerque Bernalillo County Water Utility Authority (ABCWUA), has developed a series of maps and associated reports, beginning in 2002, that document groundwater levels in the production zone of the Santa Fe Group aquifer system beneath a large area of the City of Albuquerque, New Mexico (hereafter called the study area). Herein, we...

The U.S. Geological Survey, in cooperation with the Albuquerque Bernalillo County Water Utility Authority (ABCWUA), has developed a series of maps and associated reports to document changes in the groundwater level in the production zone of the Santa Fe Group aquifer system in the Albuquerque, New Mexico, area. The current map and associated report document the construction of contours...

The Wind River Basin in central Wyoming is one of many structural and sedimentary basins that formed in the Rocky Mountain foreland during the Laramide orogeny. The basin is bounded by the Washakie, Owl Creek, and southern Bighorn uplifts on the north, the Casper arch on the east, the Granite Mountains uplift on the south, and Wind River uplift on the west.The first commercial oil well...

The Bighorn Basin is one of many structural and sedimentary basins that formed in the Rocky Mountain foreland during the Laramide orogeny. The basin is nearly 180 miles long, 100 miles wide, and encompasses about 10,400 square miles in northern Wyoming and southern Montana. The basin is bounded by major basement uplifts that include the Pryor uplift on the northeast, the Beartooth uplift...

The geologic map of the Pagosa Springs 7.5’ quadrangle in southwestern Colorado includes the town of Pagosa Springs that is partly known for its hot springs. The quadrangle is southwest of the San Juan volcanic mountains (Oligocene) and north of the San Juan Basin. All bedrock units exposed in the map area are Upper Cretaceous in age except a minor canyon outcrop of Jurassic rock. Early...

This geologic map of the central Beaverhead Mountains portrays a complex geologic history of depositional basin development interspersed with deformational events. Generalized geology for young basins, compiled from sources on both sides of the range, is combined with newly mapped bedrock geology to better integrate geologic development of the map area.Successive extensional basins were...

The geologic map of the northern half of the Lake Walcott 30ʹ×60ʹ quadrangle shows the volcanic geology of the southern part of the Craters of the Moon lava field, the complex geologic features of the Holocene Kings Bowl and Wapi lava fields, and the southern part of the Great Rift volcanic rift zone. The long extent and distribution of skylights in lava-tube systems of the Horse Butte...

The rocks and landforms of the Fort Collins 30′ × 60′ 1:100,000-scale U.S. Geological Survey quadrangle reveals a particularly complete record of geologic history in the northern Front Range of Colorado. The Proterozoic basement rocks exposed in the core of the range preserve evidence of Paleoproterozoic marine sedimentation, volcanism, and regional soft-sediment deformation, followed by...

The geologic map of the San Antonio Mountain area in northern New Mexico and southern Colorado is located along the west-central part of the San Luis Valley. The San Luis Valley is the geomorphic expression of the San Luis Basin, an extensional basin associated with the northern Rio Grande rift. Deposits within the map area record volcanic, sedimentary, and tectonic processes over the...

This map summarizes the geology of the U.S. Geological Survey Osage SW 7.5-minute quadrangle in the Ozark Plateaus region of northern Arkansas. Physiographically, the Osage SW quadrangle is located within a transitional area between the Boston Mountains to the south, and the Springfield Plateau to the north. Geologically, the area is on the southern flank of the Ozark dome; an uplift...