The Denver Basin, variously referred to as the Julesburg Basin, Denver-Julesburg Basin (after

Julesburg, Colorado Julesburg is the statutory town that is the county seat and the most populous municipality of Sedgwick County, Colorado, United States. The population was 1,225 at the 2010 United States Census. It is close to the Nebraska border. History T ...

), or the D-J Basin, is a

geologic Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Eart ...

structural basin A structural basin is a large-scale structural formation of rock strata formed by tectonic warping of previously flat-lying strata. They are geological depressions, the inverse of domes. Elongated structural basins are also known as synclines. ...

centered in eastern

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, but extending into southeast

Wyoming Wyoming () is a U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the south ...

, western

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwe ...

, and western

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the ...

. It underlies the

Denver-Aurora Metropolitan Area Denver is the central city of a conurbation region in the U.S. state of Colorado. The conurbation includes one continuous region consisting of the six central counties of Adams, Arapahoe, Broomfield, Denver, Douglas, and Jefferson. The Denver r ...

on the eastern side of the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico in ...

Geology

The basin consists of a large asymmetric

syncline In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimpose ...

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

, and

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

layers, trending north to south along the east side of the

Front Range The Front Range is a mountain range of the Southern Rocky Mountains of North America located in the central portion of the U.S. State of Colorado, and southeastern portion of the U.S. State of Wyoming. It is the first mountain range encountere ...

from the vicinity of

Pueblo In the Southwestern United States, Pueblo (capitalized) refers to the Native tribes of Puebloans having fixed-location communities with permanent buildings which also are called pueblos (lowercased). The Spanish explorers of northern New Spain ...

northward into

. The basin is deepest near Denver, where it reaches a depth of approximately 13,000 ft (3900 m) below the surface. The basin is strongly asymmetric: the

Dakota Sandstone The Dakota is a sedimentary rock, sedimentary geologic unit name of Formation (stratigraphy), formation and Group (stratigraphy), group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and ...

outcrops in a "hog-back" ridge near

Morrison Morrison may refer to: People * Morrison (surname), people with the Scottish surname Morrison * Morrison Heady (1829–1915), American poet * Morrison Mann MacBride (1877–1938), Canadian merchant Places in the United States * Morrison, Colorad ...

a few miles west of Denver, reaches its maximum depth beneath Denver, then ascends very gradually to its eastern outcrop in central

. The Dakota hogback exposes Dakota Sandstone overlying and protecting the

Morrison Formation The Morrison Formation is a distinctive sequence of Late Jurassic, Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandsto ...

beneath and to the west. Between Golden and Morrison, the Dakota hogback is called Dinosaur Ridge and is the site of a

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

trackway Historic roads (historic trails in USA and Canada) are paths or routes that have historical importance due to their use over a period of time. Examples exist from prehistoric times until the early 20th century. They include ancient trackway ...

and dinosaur fossils exposed in the outcrop that are part of a Colorado State Natural Area and Geological Points of Interest. The Lyons and Lykins formations outcrop in a smaller hogback. Farther west, the

Fountain Formation The Fountain Formation is a Pennsylvanian bedrock unit consisting primarily of conglomerate, sandstone, or arkose, in the states of Colorado and Wyoming in the United States, along the east side of the Front Range of the Rocky Mountains, and a ...

outcrops as

flatirons The Flatirons are rock formations in the western United States, near Boulder, Colorado, consisting of flatirons. There are five large, numbered Flatirons ranging from north to south (First through Fifth, respectively) along the east slope of ...

and forms the namesake of the

Red Rocks Park Red Rocks Park is a mountain park in Jefferson County, Colorado, owned and maintained by the city of Denver as part of the Denver Mountain Parks system. The park is known for its very large red sandstone outcrops. Many of these rock formations wi ...

and

Amphitheatre An amphitheatre (British English) or amphitheater (American English; both ) is an open-air venue used for entertainment, performances, and sports. The term derives from the ancient Greek ('), from ('), meaning "on both sides" or "around" and ...

. Here, against the eastern edge of the

Rocky Mountain Front The Rocky Mountain Front is a somewhat unified geologic and ecosystem area in North America where the eastern slopes of the Rocky Mountains meet the plains. In 1983, the Bureau of Land Management called the Rocky Mountain Front "a nationally signif ...

range, the Fountain Formation is in nonconformable contact with the

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

crystalline rock of the Idaho Springs Formation. The basin started forming as early as 300 million years ago, during the

Colorado orogeny The Colorado orogeny was an episode of mountain building (an ''orogeny'') in Colorado and surrounding areas. This took place from 1780 to 1650 million years ago (Mya (unit), Mya), during the Paleoproterozoic (Statherian Period). It is recorded in th ...

that created the Ancestral Rockies. Rocks formed during this time include the

, which is most prominently visible at

Red Rocks Red Rocks Amphitheatre (also colloquially as simply Red Rocks) is an open-air amphitheatre built into a rock structure in the western United States, near Morrison, Colorado, west of Denver. There is a large, tilted, disc-shaped rock behind th ...

and the Boulder

Flatirons The Flatirons are rock formations in the western United States, near Boulder, Colorado, consisting of flatirons. There are five large, numbered Flatirons ranging from north to south (First through Fifth, respectively) along the east slope of ...

. The present basin was within the

Cretaceous Interior Seaway The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient se ...

, which deposited a thick Cretaceous section in the basin. Dinosaur fossils from the

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

have been unearthed in the Denver Basin. The basin was most likely further deepened in

Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...

time, between 66 and 45 million years ago, during the

Laramide orogeny The Laramide orogeny was a time period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the o ...

that created the modern Colorado Rockies. In particular, the uplifting of the Rockies in the

caused the crust near Denver to buckle downward on the eastern side, deepening the basin. The basin later became filled with sediment

eroded 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, tra ...

from the Rockies. The Front Range peaks rise approximately 22,000 ft (6600 m) from the floor of the basin under Denver. The deep part of the basin near Denver became filled with Paleogene

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

and conglomerate, a layer now called the

Denver Formation The Denver Formation is a geological formation that is present within the central part of the Denver Basin that underlies the Denver, Colorado, area. It ranges in age from latest Cretaceous (Maastrichtian) to early Paleocene, and includes sediment ...

. In the regions to the north and south of Denver, however, stream erosion removed the Paleogene layers, revealing the underlying

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

Pierre Shale The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from Pembina Valley in Canada to New Mexico. The Pierre Shale was described by Meek and Hayden in 1862 in th ...

Natural resources

Petroleum

The basin itself forms a

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

province. Oil and gas have been produced from the Denver Basin since the discovery in 1901 of oil in fractured

at the McKenzie Well, part of the Boulder oil field in Boulder County. The great majority of Denver Basin oil and gas fields produce from

sandstones, although the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

Lyons Sandstone Lyons Sandstone is a geological layer formed during the Paleozoic Era, Middle Permian Period about 250 million years ago. This layer is also referred to as the Lyons Formation. It is the result of fine-grained quartz sand dunes compressing into ...

is also a producer. Oil has also been produced from Permian sandstones and dolomites and Pennsylvanian

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

s in the

part of the basin. The

Wattenberg Gas Field The Wattenberg Gas Field is a large producing area of natural gas and condensate in the Denver Basin of central Colorado, USA. Discovered in 1970, the field was one of the first places where massive hydraulic fracturing was performed routinely and ...

, one of the largest

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

deposits in the

, is a basin-centered gas field just north of the Denver metropolitan area. The field has produced more than 4.0 trillion cubic feet (TCF) of natural gas from the J Sandstone,

Codell Sandstone Codell is an unincorporated community in Rooks County, Kansas, United States. As of the 2020 census, the population of the community and nearby areas was 49. History Codell was established as a Union Pacific Railroad depot in 1887. Union Paci ...

Niobrara Formation The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is compose ...

, and the Hygiene Sandstone, and Terry Sandstone members of the

, (all

). In 2007, the field made 11 million barrels of oil and 170 billion cubic feet (BCF) of gas from more than 14,000 wells, making it the 9th largest source of natural gas in the United States.

Biogenic A biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of p ...

is recovered from shallow gas fields (less than 3,000 feet) of the

in Yuma, Phillips, and

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

counties of northeastern

and

Cheyenne The Cheyenne ( ) are an Indigenous people of the Great Plains. Their Cheyenne language belongs to the Algonquian language family. Today, the Cheyenne people are split into two federally recognized nations: the Southern Cheyenne, who are enroll ...

and

Sherman Sherman most commonly refers to: *Sherman (name), a surname and given name (and list of persons with the name) ** William Tecumseh Sherman (1820–1891), American Civil War General *M4 Sherman, a tank Sherman may also refer to: Places United St ...

counties of northwestern

. To date, 2,900 wells have produced of gas. Drilling is currently very active, and the play is expanding into

Perkins Perkins is a surname derived from the Anglo-Saxon corruption of the kin of Pierre (from Pierre kin to Pierrekin to Perkins), introduced into England by the Norman Conquest. It is found throughout mid- and southern England. Another derivation com ...

Chase Chase or CHASE may refer to: Businesses * Chase Bank, a national bank based in New York City, New York * Chase Aircraft (1943–1954), a defunct American aircraft manufacturing company * Chase Coaches, a defunct bus operator in England * Chase Co ...

, and Dundy counties, Nebraska.

Coal

Bituminous Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...

has been mined by underground methods in the Denver Basin, at Superior and

Louisville, Colorado The City of Louisville () is a home rule municipality located in southeastern Boulder County, Colorado, United States. The city population was 21,226 at the 2020 United States Census. Louisville began as a mining community in 1877, experienced a ...

and other locations along the western edge of the basin. The coal comes from the

Laramie Formation The Laramie Formation is a geologic formation of Late Cretaceous (Maastrichtian) age, named by Clarence King in 1876 for exposures in northeastern Colorado, in the United States.King, C. 1876. Report of the Geological Exploration of the Fortieth P ...

. Mining began in the late 1850s and stopped in 1979. Large

lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat ...

deposits are present in the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...

in the central part of the basin, in a north-south belt east of

Denver Denver () is a consolidated city and county, the capital, and most populous city of the U.S. state of Colorado. Its population was 715,522 at the 2020 census, a 19.22% increase since 2010. It is the 19th-most populous city in the Unit ...

and

Colorado Springs Colorado Springs is a home rule municipality in, and the county seat of, El Paso County, Colorado, United States. It is the largest city in El Paso County, with a population of 478,961 at the 2020 United States Census, a 15.02% increase since ...

, in Adams,

Arapahoe The Arapaho (; french: Arapahos, ) are a Native American people historically living on the plains of Colorado and Wyoming. They were close allies of the Cheyenne tribe and loosely aligned with the Lakota and Dakota. By the 1850s, Arapaho band ...

, Elbert, and

El Paso El Paso (; "the pass") is a city in and the seat of El Paso County in the western corner of the U.S. state of Texas. The 2020 population of the city from the U.S. Census Bureau was 678,815, making it the 23rd-largest city in the U.S., the s ...

counties. Some mining was done from about 1886 to 1940, but was reportedly minor.

Groundwater

The Denver Basin aquifer system consists of a layered sequence of four aquifers in beds of permeable conglomerate, sandstone, and siltstone. Layers of relatively impermeable shale separate the aquifers and impede the vertical movement of ground water between the aquifers. The northern part of this aquifer system underlies the surficial aquifer of the South Platte River. Although the Denver Basin aquifer system and the surficial aquifer are hydraulically connected in part of this area, they primarily function as separate aquifer systems which serve as important sources of water supply in the region. Denver and its suburbs such as the communities in Douglas County draw ground water from the aquifers in the Denver Basin. There is recharge of about 40,000 acre-feet per year from the broken land to the west of the basin and withdrawals of about 10 times as much. Ground water levels have dropped in the aquifers especially near population centers which draw on the aquifers for water.

Cement, construction aggregate and dimension stone

Raw materials are mined from the

and

and made into

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mix ...

at the

Cemex CEMEX S.A.B. de C.V., known as Cemex, is a Mexican multinational building materials company headquartered in San Pedro, near Monterrey, Mexico. It manufactures and distributes cement, ready-mix concrete and aggregates in more than 50 countries. ...

plant near

Lyons, Colorado The Town of Lyons is a Statutory Town in Boulder County, Colorado, United States. The town population was 2033 at the 2010 United States Census, up from 1585 at the 2000 United States Census. Lyons is located at the confluence of North St. Vr ...

. Sand and gravel for

construction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and com ...

are a major mineral resource in the Denver Basin. The Lyons Formation provides

flagstone Flagstone (flag) is a generic flat stone, sometimes cut in regular rectangular or square shape and usually used for paving slabs or walkways, patios, flooring, fences and roofing. It may be used for memorials, headstones, facades and other con ...

from quarries in Boulder and Larimer counties, along the western edge of the basin.

Gold

Small amounts of

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...

have been mined from sands and gravels in the Denver area since the

Pikes Peak Gold Rush The Pike's Peak Gold Rush (later known as the Colorado Gold Rush) was the boom in gold prospecting and mining in the Pike's Peak Country of western Kansas Territory and southwestern Nebraska Territory of the United States that began in July 1858 a ...

of 1858. Some sand and gravel pits still recover gold in their washing operations.

Uranium

A small amount of uranium ore has been mined from the

Morrison, Colorado The Town of Morrison is a Colorado municipalities#Home rule municipality, home rule municipality in Jefferson County, Colorado, Jefferson County, Colorado, United States. The population was 428 at the 2010 United States Census, 2010 census. Red R ...

, where the sandstone is impregnated with petroleum.

Uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

is known to exist in roll-front type deposits in the Denver Basin, but the basin has never been a major source of uranium.Louis J. O'Connor and Bruce D. Smith (1978) ''Magnetic and electrical study of a roll-front uranium deposit in the Denver Basin, Colorado'', in ''Energy Resources of the Denver Basin'', Denver:

Rocky Mountain Association of Geologists The Rocky Mountain Association of Geologists (RMAG), based in Denver, Colorado, is one of the oldest and largest regional geological societies in the United States. The society is a nonprofit organization founded in 1922. It is a regional affili ...

, p.153-159.

References

*''Roadside Geology of Colorado'', Halka Chronic, Mountain Press Publishing Company,

Missoula, Montana Missoula ( ; fla, label=Salish language, Séliš, Nłʔay, lit=Place of the Small Bull Trout, script=Latn; kut, Tuhuⱡnana, script=Latn) is a city in the U.S. state of Montana; it is the county seat of Missoula County, Montana, Missoula Cou ...

(1980).

External links and further reading

* Emmons, Samuel Franklin, 1841-1911; Cross, Whitman, 1854-1949; Eldridge, George Homans, 1854-1905,
Geology of the Denver basin in Colorado
' (1896) Washington D.C, Government Printing Office
Kansas Geological Survey: ''Geological Overview of the Niobrara Chalk Natural Gas Play''

2002 ''USGS Assessment of Oil and Gas Resource Potential of the Denver Basin Petroleum Province of Colorado, Kansas, Nebraska, South Dakota, and Wyoming''

Colorado Geological Survey: ''Sedimentary Rock Aquifers: Denver Basin''
{{coord, 40, -105, dim:300000_region:region:US-CO_type:landmark, name=Denver Basin, display=title Structural basins of the United States Sedimentary basins of North America Coal mining regions in the United States Geologic provinces of Colorado Geology of Wyoming Geology of Kansas Geology of Nebraska Geology of the Rocky Mountains Mining in Colorado