The central Colorado volcanic field (CCVF) is a

volcanic field A volcanic field is an area of Earth's crust that is prone to localized volcanic activity. The type and number of volcanoes required to be called a "field" is not well-defined. Volcanic fields usually consist of clusters of up to 100 volcanoes ...

in Park County,

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 ...

. It is located in the southern

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 ...

and covered a roughly triangular area centered on the Thirtynine Mile volcanic area and extending from the Sawatch Range southeast to the northern

Sangre de Christo Range , country= United States , subdivision1= Colorado , subdivision2_type= Counties , subdivision2= , parent= Sangre de Cristo Mountains, Rocky Mountains , borders_on= , geology= , age= , orogeny= Fault-block mountains , area_mi2= ...

and the

Wet Mountains The Wet Mountains are a small mountain range in southern Colorado, named for the amount of snow they receive in the winter as compared to the dried Great Plains to the east. They are a sub-range of the Sangre de Cristo Mountains, in the southern R ...

and northeast to the southern Front Range south 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 ...

. The area covered by the volcanic products of the eruptions included some produced by at least ten volcanic centers or

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

s. The field overlaps the

San Juan volcanic field The San Juan volcanic field is part of the San Juan Mountains in southwestern Colorado. It consists mainly of volcanic rocks that form the largest remnant of a major composite volcanic field that covered most of the southern Rocky Mountains in t ...

to the west. The volcanic products date from the late

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

to the early

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

().

Economic significance

Rocks of the CCVF host base- and

precious metal Precious metals are rare, naturally occurring metallic chemical elements of high economic value. Chemically, the precious metals tend to be less reactive than most elements (see noble metal). They are usually ductile and have a high lustre. ...

deposits, including the volcanic diatreme at Cripple Creek, the site of a notable

gold rush A gold rush or gold fever is a discovery of gold—sometimes accompanied by other precious metals and rare-earth minerals—that brings an onrush of miners seeking their fortune. Major gold rushes took place in the 19th century in Australia, New Z ...

beginning in 1890. By 1900, more than 500 mines had been established in the Cripple Creek district, and the population exceeded 35,000. Open-pit gold mining continues today. Outcrops of Wall Mountain

Tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...

, one of the most widespread extrusive units of the CCVF, may be found near the town of Castle Rock, more than from the presumed eruptive source of the tuff. Locally known as Castle Rock

Rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

, the stone was quarried for

dimension stone Dimension stone is natural stone or rock that has been selected and finished (e.g., trimmed, cut, drilled, ground, or other) to specific sizes or shapes. Color, texture and pattern, and surface finish of the stone are also normal requirements. A ...

and

construction aggregate Construction aggregate, or simply aggregate, is a broad category of coarse- to medium-grained particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates ...

beginning in 1872 and used in building projects in cities along the Front Range, including Denver and Colorado Springs. The quarries were once important to the economy of the town of Castle Rock: in 1900, the quarries produced up to 1800 rail cars of stone per year and employed up to 100 laborers. Although major operations ceased in 1906, at least one quarry operated as of 2013.

Notable geological features

References

{{DEFAULTSORT:Central Colorado volcanic field

Landforms of Park County, Colorado Eocene volcanism Oligocene volcanism

Economic significance

Notable geological features

See also

References