Geologic units in El Paso county, Texas

Sand sheet deposits (Holocene) at surface, covers 32 % of this area

Sand sheet deposits

Alluvium (Holocene) at surface, covers 15 % of this area

Alluvium

Bolson deposits (Pleistocene and Holocene) at surface, covers 13 % of this area

Bolson deposits

Alluvial fan deposits (Pleistocene and Holocene) at surface, covers 10 % of this area

Alluvial fan deposits

Older alluvial deposits (Pleistocene) at surface, covers 8 % of this area

Older alluvial deposits

Quaternary-Tertiary bolson deposits (Pliocene to Pleistocene) at surface, covers 7 % of this area

Quaternary-Tertiary bolson deposits

Dune sand sheet deposits (Holocene) at surface, covers 5 % of this area

Dune sand sheet deposits

Hueco Limestone (Permian; Wolfcamp Series) at surface, covers 3 % of this area

Hueco Limestone

Mingus Formation (Pennsylvanian; Des Moines Series) at surface, covers 1 % of this area

Mingus Formation

El Paso Formation and Bliss Sandstone, undivided (Late Cambrian? to Early Ordovician) at surface, covers 1 % of this area

El Paso Formation and Bliss Sandstone, undivided

Granite (preCambrian (Proterozoic); Grenville Series) at surface, covers 0.9 % of this area

Granite

Fusselman Dolomite (Early and Middle Silurian) at surface, covers 0.5 % of this area

Fusselman Dolomite

Llanoria Quartzite (preCambrian (Proterozoic); Grenville Series) at surface, covers 0.4 % of this area

Llanoria Quartzite

Montoya Dolomite (Middle and Late Ordovician) at surface, covers 0.4 % of this area

Montoya Dolomite

Oligocene intrusive rocks (Oligocene) at surface, covers 0.4 % of this area

Oligocene intrusive rocks

Rhyolite (preCambrian (Proterozoic); Grenville Series) at surface, covers 0.3 % of this area

Rhyolite

Helms Shale, Rancheria Formation, Las Cruces Limestone, Percha Shale, and Canutillo Formations, undivided (Late Mississippian; Chesteran; and Devonian) at surface, covers 0.3 % of this area

Helms Shale, Rancheria Formation, Las Cruces Limestone, Percha Shale, and Canutillo Formations, undivided

Paleozoic rocks, undivided (Paleozoic) at surface, covers 0.1 % of this area

Paleozoic rocks, undivided

Eocene intrusive rocks (Eocene) at surface, covers 0.1 % of this area

Eocene intrusive rocks

Alluvium (Holocene to upper Pleistocene) at surface, covers < 0.1 % of this area

Alluvium

Mundy Breccia and Castner Limestone, undivided (preCambrian (Proterozoic)) at surface, covers < 0.1 % of this area

Mundy Breccia and Castner Limestone, undivided

Cretaceous rocks, undivided (Late Cretaceous) at surface, covers < 0.1 % of this area

Cretaceous rocks, undivided

Upper Santa Fe Group (Middle Pleistocene to uppermost Miocene) at surface, covers < 0.1 % of this area

Includes Camp Rice, Fort Hancock, Palomas, Sierra Ladrones, Arroyo Ojito, Ancha, Puye, and Alamosa Formations.

Magdalena Formation (Pennsylvanian to Permian?) at surface, covers < 0.1 % of this area

Magdalena Formation

Piedmont alluvial deposits (Holocene to lower Pleistocene) at surface, covers < 0.1 % of this area

Includes deposits of higher gradient tributaries bordering major stream valleys, alluvial veneers of the piedmont slope, and alluvial fans. May locally include uppermost Pliocene deposits.

Pennsylvanian rocks, undivided (Pennsylvanian) at surface, covers < 0.1 % of this area

In Sangre de Cristo Mountains may include Sandia, Madera, La Pasada, Alamitos, and Flechado Formations; elsewhere may include Bar-B, Nakaye, Red House, Oswaldo, and Syrena Formations.

Hueco Formation or Group (Wolfcampian) at surface, covers < 0.1 % of this area

Limestone unit restricted to south-central area; Pendejo Tongue of Hueco Formation divides Abo Formation into upper and lower parts in Sacramento Mountains.

Mississippian and Devonian rocks, undivided (Mississippian and Devonian) at surface, covers < 0.1 % of this area

Includes Helms, Rancheria, Las Cruces, Lake Valley, and Caballero Formations and Escabrosa Group (Mississippian); Percha Shale, Contadero, Sly Gap, and Onate Formations of south-central New Mexico, and Canutillo Formation of northern Franklin Mountains and Bishops Cap area (Devonian).

Silurian and Ordovician rocks, undivided (Silurian and Ordovician) at surface, covers < 0.1 % of this area

Silurian and Ordovician rocks, undivided