Surficial Geology of the Northern San Luis Valley, Saguache, Fremont, Custer, Alamosa, Rio Grande, Conejos, and Costilla Counties, Colorado
Scientific Investigations Map
3475
Links
- Sheets:
- Related Works:
- Scientific Investigations Map 3342— Geologic map of the Alamosa 30’ × 60’ quadrangle, south-central Colorado
- Scientific Investigations Map 3346— Geologic map of the Poncha Pass area, Chaffee, Fremont, and Saguache Counties, Colorado
- Data Release: USGS data release - Data release for Surficial Geology of the Northern San Luis Valley, Saguache, Fremont, Custer, Alamosa, Rio Grande, Conejos, and Costilla Counties, Colorado
- Read Me: Read Me (7.0 kB txt)
- Download citation as: RIS | Dublin Core
Abstract
The San Luis Valley and associated underlying basin of south-central Colorado and north-central New Mexico is the largest structural and hydrologic basin of the Rio Grande Rift and fluvial system. The surrounding San Juan and Sangre de Cristo Mountains reveal evidence of widespread volcanism and transtensional tectonism beginning in the Oligocene and continuing to the present, as seen in fault displacement of Pleistocene to Holocene deposits along the eastern basin-bounding Sangre de Cristo fault system and fault zones along the western margin of the basin. The San Luis basin can generally be subdivided into northern and southern basins at the structural and physiographic high terrain of the San Luis Hills in the center of the basin, proximal to the Colorado-New Mexico stateline. The northern San Luis Valley can be subdivided into two subbasins at approximately the latitude of the Great Sand Dunes and San Luis Lakes, where the endorheic northern subbasin surface and subsurface flow currently accumulate in a series of playa lakes. To the south of this playa region, the Rio Grande has captured basin hydrology into a through-going fluvial system cutting through the San Luis Hills, carving the Rio Grande gorge, and ultimately flowing into the Gulf of Mexico. This surficial geologic map of the northern San Luis Valley, paired with the Alamosa, CO 1:100,000-scale geologic map (U.S. Geological Survey Scientific Investigations Map 3342) provides new and compiled geologic mapping that characterizes basin deposits and locates the traces of active faults, with the goal to provide geospatial data for future investigations related to western North American neotectonics, Pleistocene paleoclimate, and related geomorphic processes. In addition, present natural and anthropogenic water bodies have been located and updated for hydrologic modeling and water-usage investigations.
Suggested Citation
Ruleman, C.A., and Brandt, T.R., 2021, Surficial geology of the northern San Luis Valley, Saguache, Fremont, Custer, Alamosa, Rio Grande, Conejos, and Costilla Counties, Colorado: U.S. Geological Survey Scientific Investigations Map 3475, 2 sheets, scale 1:75,000, https://doi.org/10.3133/sim3475.
ISSN: 2329-132X (online)
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Surficial geology of the northern San Luis Valley, Saguache, Fremont, Custer, Alamosa, Rio Grande, Conejos, and Costilla Counties, Colorado |
| Series title | Scientific Investigations Map |
| Series number | 3475 |
| DOI | 10.3133/sim3475 |
| Publication Date | June 22, 2021 |
| Year Published | 2021 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Contributing office(s) | Geosciences and Environmental Change Science Center |
| Description | 4 Sheets: 52.81 x 75.84 inches or smaller; ReadMe; Data Release |
| Country | United States |
| State | Colorado |
| County | Saguache County, Fremont County, Custer County, Alamosa County, Rio Grande County, Conejos County, Costilla County |
| Online Only (Y/N) | Y |