The Santa Fe Group is a

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

of geologic formations in

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

and

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

. It contains

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s characteristic of the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

through

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

epochs In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

. The group consists of basin-filling

sedimentary Sedimentary rocks are types of rock formed by the cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedime ...

and

volcanic rock Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...

s of the

Rio Grande rift The Rio Grande rift is a north-trending continental rift zone. It separates the Colorado Plateau in the west from the interior of the North American craton on the east. The rift extends from central Colorado in the north to the state of Chihuah ...

, and contains important regional

aquifer An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...

Description

The Santa Fe Group is widely defined as basin-filling sedimentary and volcanic rocks of the

. These range in age from late Oligocene to Pleistocene. The oldest formations in the group correspond to the earliest structural deformation associated with

rifting In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear Fault (geology), downfaulted depression, called a graben, or more commonly ...

Geologic uplift Orogeny () is a mountain-building process that takes place at a convergent plate margin when plate motion compresses the margin. An or develops as the compressed plate crumples and is uplifted to form one or more mountain ranges. This involv ...

of the region around the rift has ended deposition, and

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

in the

Rio Grande The Rio Grande ( or ) in the United States or the Río Bravo (del Norte) in Mexico (), also known as Tó Ba'áadi in Navajo language, Navajo, is one of the principal rivers (along with the Colorado River) in the Southwestern United States a ...

river system has exposed many of the beds deposited earlier, often spectacularly, as in the

badlands Badlands are a type of dry terrain where softer sedimentary rocks and clay-rich soils have been extensively eroded."Badlands" in '' Chambers's Encyclopædia''. London: George Newnes, 1961, Vol. 2, p. 47. They are characterized by steep slopes, ...

north of Santa Fe. The formations in the group are divided into lower and upper sections. The lower Santa Fe Group was deposited in bolsons (closed arid basins) where streams drained into intermittent

playa lake A dry lake bed, also known as a playa (), is a basin or Depression (geology), depression that formerly contained a standing surface water body, which disappears when evaporation processes exceed recharge. If the floor of a dry lake is covered b ...

s surrounded by

piedmont Piedmont ( ; ; ) is one of the 20 regions of Italy, located in the northwest Italy, Northwest of the country. It borders the Liguria region to the south, the Lombardy and Emilia-Romagna regions to the east, and the Aosta Valley region to the ...

deposits eroded from basin-margin uplifts. The upper Santa Fe Group was deposited after

integration Integration may refer to: Biology *Multisensory integration *Path integration * Pre-integration complex, viral genetic material used to insert a viral genome into a host genome *DNA integration, by means of site-specific recombinase technology, ...

of these basins into the ancestral Rio Grande, so that their drainage flowed toward southern New Mexico. Some geologists also define a middle section transitional between the upper and lower sections.

Formations

Formations of the Santa Fe Group are defined in each basin of the Rio Grande rift, though some formations extend across multiple basins.

San Luis Basin

Upper Santa Fe Group: * Alamosa Formation The lower Santa Fe Group is present only in the subsurface in the San Luis Basin and has not been divided into formations.

Espanola Basin

Upper Santa Fe Group: * Ancha Formation * Puye Formation * Cochiti Formation Lower Santa Fe Group: *

Chamita Formation The Chamita Formation is a Formation (geology), geologic formation in north-central New Mexico. It preserves unique fossils dating back to the Neogene Period (geology), period. The presence of volcanic ash beds in the formation, which can be Rad ...

* Tesuque Formation * Abiquiu Formation

Hagen Basin

Upper Santa Fe Group: * Tuerto Formation Lower Santa Fe Group: * Blackshare Formation * Tanos Formation

Northwest Albuquerque Basin

Upper Santa Fe Group: * Sierra Ladrones Formation * Cochiti Formation * Ceja Formation * Arroyo Ojito Formation Middle Santa Fe Group: * Cerro Conejo Formation Lower Santa Fe Group: * Zia Formation

Southern and eastern Albuquerque Basin

Upper Santa Fe Group: * Sierra Ladrones Formation Lower Santa Fe Group: * Popotosa Formation

Orogrande Basin

Upper Santa Fe Group: *

Camp Rice Formation The Camp Rice Formation is a geologic formation in west Texas and southern New Mexico. It preserves fossils of the Pliocene-Pleistocene. These include the distinctive Tonuco Mountain Local Fauna. Description The formation consists of poorly cem ...

* Palomas Formation Lower Santa Fe Group: * Rincon Valley Formation * Hayner Ranch Formation

Fossils

G.K. Gilbert visited

San Ildefonso Pueblo San Ildefonso Pueblo (Tewa language, Tewa: Pʼohwhogeh Ówîngeh ’òhxʷógè ʔówîŋgè"where the water cuts through" ), also known as the Turquoise Clan, is a census-designated place (CDP) in Santa Fe County, New Mexico, Santa Fe Coun ...

with the

Hayden Survey Ferdinand Vandeveer Hayden (September 7, 1829 – December 22, 1887) was an American geologist noted for his pioneering surveying expeditions of the Rocky Mountains in the late 19th century. He was also a physician who served with the Union A ...

in 1873 and found fossil mammal bones characteristic of the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Othniel Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of paleontology. A prolific fossil collector, Marsh was one of the preeminent paleontologists of the nineteenth century. Among his legacies are the discovery or ...

. Marsh's bitter rival,

Edward Drinker Cope Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontology, paleontologist, comparative anatomy, comparative anatomist, herpetology, herpetologist, and ichthyology, ichthyologist. Born to a wealthy Quaker fam ...

, arrived at San Ildefonso the next year and collected a number of

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

reptile, bird, and mammal fossils.

Childs Frick Childs Frick (March 12, 1883 - May 8, 1965) was an American vertebrate paleontologist. He was a trustee of the American Museum of Natural History and a major benefactor of its Department of Paleontology, which in 1916 began a long partnership wi ...

sent an expedition into the Tesuque area in 1924, and immediately recognized the paleontological potential of the Santa Fe beds. The Fricks Laboratory (merged with the Department of Vertebrate Paleontology of the

American Museum of Natural History The American Museum of Natural History (AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. Located in Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 21 interconn ...

in 1968) carried out field work through 1972. Work prior to 1940 was careless about identifying exact source strata, though greater care was taken thereafter. Most of the fossils came from the Pojoaque

Member Member may refer to: * Military jury, referred to as "Members" in military jargon * Element (mathematics), an object that belongs to a mathematical set * In object-oriented programming, a member of a class ** Field (computer science), entries in ...

of the Tesuque Formation and were almost entire found within thin (0.5–3 m) maroon-red to pale green

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone and shale. Most of the particles of which the stone is composed are less than and are too small to ...

to fine-grained

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

beds of lithosome B. These are interpreted as small

lacustrine A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from t ...

deposits. Fossils found in the Santa Fe Group include the hemicyonid '' Hemicyon'' and the borophagine canid '' Carpocyon webbi'', the antilocaprids ''

Cosoryx ''Cosoryx'' is an extinct genus of antilocaprid that lived in the Miocene of Nevada. Fossils of this genus have also been found in the Santa Fe Group in New Mexico. ''Cosoryx'' has sometimes been considered synonymous with ''Merycodus '' ...

'', ''

Merycodus ''Merycodus'' is an extinct genus of the artiodactyl family Antilocapridae. Fossils of this genus have been found in the Santa Fe Group of New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the ...

'', and ''

Ramoceros ''Ramoceros'' is an extinct genus of the artiodactyl family Antilocapridae endemic to Middle Miocene (Clarendonian) North America.Blount, Kitty and Crowley, Maggie. ''Encyclopedia of Dinosaurs & Prehistoric Life'', p. 271 (Penguin, 2008). Taxon ...

'',

chiroptera Bats are flying mammals of the order Chiroptera (). With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most birds, flying with their very long spread-out ...

from the

Vespertilionidae Vespertilionidae is a family of microbats, of the order Chiroptera, flying, insect-eating mammals variously described as the common, vesper, or simple nosed bats. The vespertilionid family is the most diverse and widely distributed of bat familie ...

and Antrozoinae, the

turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

'' Glyptemys valentinensis'', and mastodonts.

Economic geology

The

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

potential of the Santa Fe Group was recognized by Bryan Kirk in 1938, and the Alamosa subbasin of the San Luis Valley, the central part of the

Albuquerque Basin The Albuquerque Basin (or Middle Rio Grande Basin) is a structural basin and ecoregion within the Rio Grande rift in central New Mexico. It contains the city of Albuquerque, New Mexico, Albuquerque. Geologically, the Albuquerque Basin is a half- ...

, and the southern Mesilla basin from Las Cruces to

El Paso El Paso (; ; or ) is a city in and the county seat of El Paso County, Texas, United States. The 2020 United States census, 2020 population of the city from the United States Census Bureau, U.S. Census Bureau was 678,815, making it the List of ...

are now among the most productive groundwater reservoirs in the western United States. In the Albuquerque area, this has produced significant drawdown of the

water table The water table is the upper surface of the phreatic zone or zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with groundwater, which may be fresh, saline, or brackish, depending on the loc ...

, in some places exceeding . The aquifer continues to be studied to characterize the effects of new development, and resulting shifts in groundwater flow, on pollutants in the aquifer.

History of investigation

Hayden gave the name "Santa Fe Marls" to the extensive sedimentary beds in the valley of the

near Santa Fe during his 1869 survey of New Mexico and Colorado. He likened these to the badlands of

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state, state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Dakota people, Dakota Sioux ...

and correctly determined that they were

upper Tertiary The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of the ...

in age and were much younger than the Galisteo Formation beds which they overlie. He noted their great thickness, which he observed to be at least . By 1936, the Santa Fe Formation had been traced from central New Mexico into southern Colorado. Two years later, Bryan recognized that it extended at least from the San Luis Basin to beyond

and was extensively faulted and deformed. He interpreted the formation as being deposited in a series of basins along an ancestral Rio Grande. The formation was promoted to

rank in 1953 and defined by Baldwin three years later as basin-filling sedimentary and volcanic rocks of the

. Galusha and Blick advocated a much narrower definition of the Santa Fe Group in 1971. They restricted it to the Tesuque Formation and

in the Espanola basin, and specifically excluded the older Abiquiu and Zia Formation and younger Ancha Formation. However, the broad 1956 definition by Baldwin has been widely accepted.

Footnotes

References

* * * * * * * * * * * * * * * * * * {{cite journal , last1=Wilmarth , first1=M.G. , title=Lexicon of geologic names of the United States (including Alaska) , journal=Geological Survey Bulletin , date=1936 , volume=896 , issue=1–2 , page=2396 Geologic groups of New Mexico Neogene formations of New Mexico Paleogene formations of New Mexico Siltstone groups Sandstone groups of the United States Conglomerate groups