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The Denver Basin, variously referred to as the Julesburg Basin, Denver-Julesburg Basin (after Julesburg, Colorado), or the D-J Basin, is a
geologic Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth s ...
structural basin A structural basin is a large-scale structural geology, structural formation of rock stratum, strata formed by tectonics, tectonic warping (Fold (geology), folding) of previously flat-lying strata into a syncline fold. They are geological dep ...
centered in eastern
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 ...
in the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
, but extending into southeast
Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...
, western
Nebraska Nebraska ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Ka ...
, and western
Kansas Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...
. It underlies the Denver-Aurora Metropolitan Area 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 great-circle distance, straight-line distance from the northernmost part of Western Can ...
.


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 superimposed ...
of
Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...
,
Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...
, and
Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...
sedimentary rock Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or de ...
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 encounter ...
from the vicinity of
Pueblo Pueblo refers to the settlements of the Pueblo peoples, Native American tribes in the Southwestern United States, currently in New Mexico, Arizona, and Texas. The permanent communities, including some of the oldest continually occupied settlement ...
northward into
Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...
. 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 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
Kansas Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...
. The Dakota hogback exposes Dakota Sandstone overlying and protecting the
Morrison Formation The Morrison Formation is a distinctive sequence of 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, sandstone, siltston ...
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 Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...
trackway Historic roads (or historic trails in the US 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 track ...
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 outcrops as flatirons and forms the namesake of the Red Rocks Park and
Amphitheatre An amphitheatre (American English, U.S. English: amphitheater) 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 ('), meani ...
. Here, against the eastern edge of the Rocky Mountain Front range, the Fountain Formation is in nonconformable contact with the
Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, 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 t ...
crystalline rock of the Idaho Springs Formation. The basin started forming as early as 300 million years ago, during the Colorado orogeny that created the Ancestral Rockies. Rocks formed during this time include the Fountain Formation, which is most prominently visible at Red Rocks and the Boulder Flatirons. The present basin was within the Cretaceous Interior Seaway, which deposited a thick Cretaceous section in the basin. Dinosaur fossils from the
Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...
have been unearthed in the Denver Basin. The basin was most likely further deepened in
Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...
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, 80 to 70 million years ago, and ended 55 to 35 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
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 encounter ...
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 water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. Erosion is disti ...
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 rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...
and conglomerate, a layer now called the
Denver Formation The Denver Formation is a geological Formation (geology), formation that is present within the central part of the Denver Basin that underlies the Denver, Colorado, area. It ranges in age from Late Cretaceous, latest Cretaceous (Maastrichtian) to ...
. 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 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
Pierre Shale.


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 chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring un ...
province. Oil and gas have been produced from the Denver Basin since the discovery in 1901 of oil in fractured Pierre Shale 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
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
sandstones, although the
Permian The Permian ( ) is a geologic period and System (stratigraphy), 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 251.902 Mya. It is the s ...
Lyons Sandstone is also a producer. Oil has also been produced from Permian sandstones and dolomites and Pennsylvanian
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
s in the
Nebraska Nebraska ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Ka ...
part of the basin. The Wattenberg Gas Field, one of the largest
natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...
deposits in the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
, 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, Niobrara Formation, and the Hygiene Sandstone, and Terry Sandstone members of the Pierre Shale, (all
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
). 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 ...
natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...
is recovered from shallow gas fields (less than 3,000 feet) of the Niobrara Formation in Yuma, Phillips, and Washington counties of northeastern
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 ...
and
Cheyenne The Cheyenne ( ) are an Indigenous people of the Great Plains. The Cheyenne comprise two Native American tribes, the Só'taeo'o or Só'taétaneo'o (more commonly spelled as Suhtai or Sutaio) and the (also spelled Tsitsistas, The term for th ...
and Sherman counties of northwestern
Kansas Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...
. To date, 2,900 wells have produced of gas. Drilling is currently very active, and the play is expanding into Perkins, Chase, and Dundy counties, Nebraska.


Coal

Bituminous Bitumen ( , ) is an immensely viscous constituent of petroleum. Depending on its exact composition, it can be a sticky, black liquid or an apparently solid mass that behaves as a liquid over very large time scales. In American English, the m ...
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 Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...
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, experienc ...
and other locations along the western edge of the basin. The coal comes from the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
Laramie Formation The Laramie Formation is a geologic formation (geology), formation of the 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 Exp ...
. Mining began in the late 1850s and stopped in 1979. Large
lignite Lignite (derived from Latin ''lignum'' meaning 'wood'), 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 ...
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), ...
Denver Formation The Denver Formation is a geological Formation (geology), formation that is present within the central part of the Denver Basin that underlies the Denver, Colorado, area. It ranges in age from Late Cretaceous, latest Cretaceous (Maastrichtian) to ...
in the central part of the basin, in a north-south belt east of
Denver Denver ( ) is a List of municipalities in Colorado#Consolidated city and county, consolidated city and county, the List of capitals in the United States, capital and List of municipalities in Colorado, most populous city of the U.S. state of ...
and
Colorado Springs Colorado Springs is the most populous city in El Paso County, Colorado, United States, and its county seat. The city had a population of 478,961 at the 2020 census, a 15.02% increase since 2010. Colorado Springs is the second-most populous c ...
, in Adams, Arapahoe, Elbert, and
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 ...
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 Niobrara Formation and Pierre Shale 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 mi ...
at the Cemex plant near Lyons, Colorado. Sand and gravel for
construction Construction are processes involved in delivering buildings, infrastructure, industrial facilities, and associated activities through to the end of their life. It typically starts with planning, financing, and design that continues until the a ...
are a major mineral resource in the Denver Basin. The Lyons Formation provides
flagstone Flagstone (flag) is a generic flat Rock (geology), stone, sometimes cut in regular rectangular or square shape and usually used for Sidewalk, paving slabs or walkways, patios, flooring, fences and roofing. It may be used for memorials, headstone ...
from quarries in Boulder and Larimer counties, along the western edge of the basin.


Gold

Small amounts of
gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...
have been mined from sands and gravels in the Denver area since the Pikes Peak Gold Rush 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 Dakota Sandstone at
Morrison, Colorado Morrison is a home rule municipality in Jefferson County, Colorado, United States. The population was 396 at the 2020 census. History This small foothills settlement is named after George Morrison (April 16, 1822 – June 11, 1895), a builde ...
, where the sandstone is impregnated with petroleum.
Uranium Uranium is a chemical element; it has chemical symbol, 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. Ura ...
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, p.153-159.


References

*''Roadside Geology of Colorado'', Halka Chronic, Mountain Press Publishing Company,
Missoula, Montana Missoula ( ) is a city in and the county seat of Missoula County, Montana, United States. It is located along the Clark Fork River near its confluence with the Bitterroot and Blackfoot rivers in western Montana and at the convergence of five ...
(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