Geologic units in Dona Ana county, New Mexico

Upper Santa Fe Group (Middle Pleistocene to uppermost Miocene) at surface, covers 42 % of this area

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

Piedmont alluvial deposits (Holocene to lower Pleistocene) at surface, covers 19 % 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.

Alluvium (Holocene to upper Pleistocene) at surface, covers 7 % of this area

Alluvium

Basaltic to andesitic lava flows (Middle to lower Pleistocene) at surface, covers 7 % of this area

Includes vent deposits.

Lacustrine and playa-lake deposits (Holocene) at surface, covers 4 % of this area

Includes associated alluvial and eolian deposits of major lake basins.

Middle Tertiary volcaniclastic sedimentary units (Oligocene to upper Eocene) at surface, covers 3 % of this area

Mostly syneruptive volcaniclastic sedimentary aprons. Lower units dominantly derived from volcanic highlands of andesitic to dacitic composition. Locally includes minor lavas and tuffs. Younger units (above and intertongued with Mogollon Group tuffs, Turp) include upper Bell Top Formation, South Crosby Peak Formation, and upper Spears Group units near Quemado. Older units (below and intertongued with Datil Group tuffs, Tlrp) include Palm Park, lower Bell Top, Espinaso and Pueblo Creek Formatios and lower Spears Group formations such as Rincon Windmill, Chavez Canyon, and Dog Springs.

Lower-upper middle Tertiary basaltic andesites and andesites of the Mogollon Group (Upper Oligocene (26-29 Ma)) at surface, covers 2 % of this area

Includes La Jara Peak Basaltic Andesite, Uvas Basaltic Andesite, basaltic andesites of Poverty Creek and Twin Peaks, Squirrel Springs Canyon Andesite, Razorback Basalt, Bear Springs Basalt, flows of Gila Flat, Salt Creek Formation, Middle Mountain Formation, and the Alum Mountain Group. Pre-Amalia-Tuff lavas in the Questa caldera are dominantly silicic andesites and dacites; elsewhere silicic lavas are a minor component of Tual.

Lower middle Tertiary rhyolitic to dacitic pyroclastic rocks of the Datil Group, ash-flow tuffs (Lower Oligocene to upper Eocene (31-36 Ma)) at surface, covers 2 % of this area

Regional ash-flow tuffs include Hell's Mesa, Kneeling Nun, Caballo Blanco, Datil Well, Leyba Well, Rock House Canyon, Blue Canyon, Sugarlump, Oak Creek, Bluff Creek, Gillespie, Box Canyon, Cooney and Chiquito Peak Tuffs; the tuffs of Steins Mountain, Black Bill Canyon, Woodhaul Canyon, and Farr Ranch; tuffs of the Organ cauldron; and lower tuffs in the Bell Top Formation. Includes some locally erupted lavas and tuffs within thick intra-caldera units; includes minor volcaniclastic sedimentary units and lavas between thin outflow sheets.

Lower Santa Fe Group (Upper Miocene to uppermost Oligocene) at surface, covers 2 % of this area

Includes Hayner Ranch, Rincon Valley, Popotosa, Cochiti, Tesuque, Chamita, Abiquiu, Zia, and other formations.

Basaltic to andesitic lava flows (Holocene to middle Pleistocene) at surface, covers 2 % of this area

Flows south of Grants and west of Carrizozo are Holocene. Includes minor vent deposits.

Mesoproterozoic granitic plutonic rocks (Mesoproterozoic) at surface, covers 1 % of this area

Mainly 1.45 - 1.35 Ga megacrystic granites, generally weakly foliated except locally at their margins.

Hueco Formation or Group (Wolfcampian) at surface, covers 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.

Tertiary intrusive rocks of intermediate to silicic composition (Pliocene to Eocene) at surface, covers 1 % of this area

Includes monzonitic to granitic plutons, stocks, laccoliths, and porphyritic dikes in deeply eroded magmatic centers; and andesitic, dacitic, or rhyolitic plugs and dikes near cauldrons or stratovolcanoes. In the Latir field, fine-grained rhyolitic dikes commonly cut coarse-grained granitic plutons. Includes alkaline laccoliths, plugs, and dikes in Colfax County. North-trending dikes near Capitan include some mafic diabase dikes.

Basaltic tephra and lavas near vents (Upper to middle Pleistocene) at surface, covers 1.0 % of this area

Tuff rings, maars, cinder cones, and minor proximal lavas. Includes maars at Killbourne Hole and Zuni Salt Lake.

Sandia Formation (Atokan) at surface, covers 0.9 % of this area

Predominately clastic unit (commonly arkosic) with minor black shales, and limestone in lower part; map unit locally includes Morrowan Osha Canyon Formation in Sierra Nacimiento.

Lower middle Tertiary volcanic rocks (Lower Oligocene to upper Eocene (older than 31 Ma)) at surface, covers 0.9 % of this area

Mostly intermediate lavas of the lower Datil Group and intermediate volcaniclastic sediments of the lower Spears Group (Tla+Tvs). Locally includes ash-flow tuffs of the upper Datil Group (Tlrp). Includes intermediate volcaniclastic sedimentary rocks of the Conejos Formation in northern New Mexico.

Gypsiferous eolian deposits (Holocene to middle Pleistocene) at surface, covers 0.7 % of this area

Gypsiferous eolian deposits.

Silurian through Cambrian rocks, undivided (Silurian through Cambrian) at surface, covers 0.7 % of this area

Silurian through Cambrian rocks, undivided

Lead Camp Formation (Atokan to Missourian) at surface, covers 0.7 % of this area

In San Andres and Organ Mountains.

Pennsylvanian rocks, undivided (Pennsylvanian) at surface, covers 0.6 % 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.

Santa Fe Group, undivided (Middle Pleistocene to uppermost Oligocene) at surface, covers 0.5 % of this area

Basin fill of the Rio Grande rift. Locally represents upper Miocene formations of the middle Santa Fe Group in the northern Albuquerque Basin.

Paleoproterozoic quartzite (Paleoproterozoic) at surface, covers 0.4 % of this area

Includes 1.70 Ga Ortega Quartzite and equivalents in northern New Mexico and 1.67 Ga quartzites in central New Mexico.

Mississippian and Devonian rocks, undivided (Mississippian and Devonian) at surface, covers 0.3 % 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).

Permian rocks, undivided (Permian) at surface, covers 0.3 % of this area

Permian rocks, undivided

Lower middle Tertiary rhyolitic lavas and local tuffs (Lower Oligocene to upper Eocene (31-36 Ma)) at surface, covers 0.2 % of this area

Includes Mimbres Peak Formation, rhyolite of Cedar Hills, and other units in the Bootheal region.

Yeso Formation (Leonardian) at surface, covers 0.2 % of this area

Sandstones, siltstones, anhydrite, gypsum, halite, and dolomite.

Abo Formation (Wolfcampian) at surface, covers 0.2 % of this area

Red beds, arkosic at base, finer and more mature above; Wolfcampian; may include limestone beds of Pennsylvanian age (Virgilian) in Zuni Mountains. In Robledo Mountains the Abo may be considered a member of the Hueco Formation.

Lower Cretaceous, undivided (Lower Cretaceous) at surface, covers 0.1 % of this area

In northern Lea and Roosevelt Counties includes equivalents of Tucumcari Shale; in Cornudas Mountains includes Campogrande and Cox Formations and Washita Group; at Cerro de Cristo Rey includes several formations of the Fredricksburg and Washita Groups, and the Boquillas Formation (Cenomanian); in the southwest includes Mojado, U-Bar (Aptian), and Hell-to-Finish Formations, whch are equivalent to Bisbee Group of Arizona.

Paleoproterozoic mafic metavolcanic rocks with subordinate felsic metavolcanic rocks (Paleoproterozoic) at surface, covers 0.1 % of this area

Includes the 1.78-1.72 Ga Moppin (Tusas Mountains), Gold Hill (Taos Range), and Pecos (Sangre de Cristo Mountains) complexes; interpreted to be supracrustal part of juvenile volcanic arc basement.

Paleoproterozoic granitic plutonic rocks (Paleoproterozoic) at surface, covers < 0.1 % of this area

Variably foliated granites and granitic gneisses; 1.71 - 1.65 Ga in northern New Mexico; 1.66 - 1.65 Ga in central and southern New Mexico.

Lower middle Tertiary andesitic to dacitic lavas and pyroclastic flow breccias (Upper to middle Eocene (33-43 Ma)) at surface, covers < 0.1 % of this area

Includes Rubio Peak Formation, Orejon Andesite, andesite of Dry Leggett Canyon, andesite of Telephone Canyon, and other units in southwestern, central, and northern New Mexico. Locally includes minor mafic lavas. Ancient landslide blocks of Mader Limestone, as much as one mile long, occur within Rubio Peak lavas in the central Black Range, west of Winston.

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

Silurian and Ordovician rocks, undivided

San Andres, Glorieta, and Yeso Formations, undivided (Guadalupian and Leonardian) at surface, covers < 0.1 % of this area

San Andres, Glorieta, and Yeso Formations, undivided

Paleogene sedimentary units (Paleogene) at surface, covers < 0.1 % of this area

Includes Baca, Galisteo, El Rito, Blanco Basin, Hart Mine, Love Ranch, Lobo, Sanders Canyon, Skunk Ranch, Timberlake, and Cub Mountain Formations.

Yeso and Abo Formations, undivided (Lower Permian) at surface, covers < 0.1 % of this area

Yeso and Abo Formations, undivided

Eolian deposits (Holocene to middle Pleistocene) at surface, covers < 0.1 % of this area

Eolian deposits.

San Andres Formation (Guadalupian and Leonardian) at surface, covers < 0.1 % of this area

Limestone and dolomite with minor shale. Guadalupian in south, in part Leonardian to north.

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

Paleozoic rocks, undivided

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

Alluvium

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

Includes Montoya Formation (or Group), El Paso Formation, and Bliss Sandstone.

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

Cretaceous rocks, undivided

Quaternary-Tertiary bolson deposits (Pliocene to Pleistocene) at surface, covers < 0.1 % of this area

Quaternary-Tertiary bolson deposits

Paleoproterozoic rhyolite and felsic volcanic schist (Paleoproterozoic) at surface, covers < 0.1 % of this area

Includes 1.70 Ga Vadito Group in northern New Mexico and 1.68 Ga Sevilleta Metarhyolite in central New Mexico.

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

Cretaceous rocks, undivided