The Carrizo Mountains are a small range 15 to 20 km (9 to 12 miles) in diameter located on the Colorado Plateau

Colorado Plateau

The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...

 in northeastern Arizona. The range is about 20 km (12.4 mi) southwest of the Four Corners. The highest summit, Pastora Peak, is 2869 m (9,412.7 ft) in elevation, whereas elevations on the surrounding plateau are near 1800 m (5,905.5 ft).

The mountains are within the Navajo Nation. Teec Nos Pos, Arizona

Teec Nos Pos, Arizona

Teec Nos Pos is a census-designated place in Apache County, Arizona, United States. The population was 799 at the 2000 census. The Navajo name of this community translates as "cottonwoods in a Circle". It is the western terminus of U.S...

, the closest community, is several miles to the north, and had about 800 inhabitants in the 2000 census.

Geology

The mountains are formed by igneous rock

Igneous rock

Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...

s that intruded and uplifted Permian

Permian

The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

 through Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 sedimentary rock

Sedimentary rock

Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....

s. The most common igneous rock type is porphyritic

Porphyritic

Porphyritic is an adjective used in geology, specifically for igneous rocks, for a rock that has a distinct difference in the size of the crystals, with at least one group of crystals obviously larger than another group...

 hornblende

Hornblende

Hornblende is a complex inosilicate series of minerals .It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole....

 diorite

Diorite

Diorite is a grey to dark grey intermediate intrusive igneous rock composed principally of plagioclase feldspar , biotite, hornblende, and/or pyroxene. It may contain small amounts of quartz, microcline and olivine. Zircon, apatite, sphene, magnetite, ilmenite and sulfides occur as accessory...

. Intrusive forms include laccolith

Laccolith

A laccolith is a sheet intrusion that has been injected between two layers of sedimentary rock. The pressure of the magma is high enough that the overlying strata are forced upward, giving the laccolith a dome or mushroom-like form with a generally planar base.Laccoliths tend to form at relatively...

s, stocks, sill

Sill (geology)

In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock. The term sill is synonymous with concordant intrusive sheet...

s, and dikes

Dike (geology)

A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across* planar wall rock structures, such as bedding or foliation...

. Age

Radiometric dating

Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...

s of the igneous rocks range from 70 to 74 million years.

The similar igneous-cored mountain ranges on the Colorado Plateau

Colorado Plateau

The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...

 fall into two age groups. The Henry Mountains

Henry Mountains

The Henry Mountains are located in the southeastern portion of the U.S. state of Utah and run in a generally north-south direction, extending over a distance of about 30 miles . They were named by John Wesley Powell in honour of Joseph Henry, the first secretary of the Smithsonian Institution. The...

, the Abajo Mountains

Abajo Mountains

The Abajo Mountains, also called the Blue Mountains, is a small mountain range west of Monticello, Utah, south of Canyonlands National Park and north of Blanding, Utah. The mountain range is located within the Manti-La Sal National Forest...

, and the La Sal Range

La Sal Range

The La Sal Mountains are located in Grand and San Juan counties, near the eastern border of the state of Utah, and rising above the town of Moab. This range is part of the Manti-La Sal National Forest and the southern Rocky Mountains. The maximum elevation is at Mount Peale, reaching 12,721 feet ...

 formed about igneous rocks 20 to 31 million years in age, and so they are distinctly younger than the major intrusions of the Carrizo Mountains. Radiometric ages of igneous intrusions in Sleeping Ute Mountain are essentially identical to those of the diorite intrusions in the Carrizos. Both the Carrizo Mountains and Sleeping Ute Mountain are in a southwest extension of the Colorado Mineral Belt

Colorado Mineral Belt

The Colorado Mineral Belt is an area with abundant ore deposits. The area stretches north-east from the La Plata Mountains in Southwestern Colorado to the Front Range near Boulder, Colorado...

, a feature defined partly by igneous rocks that are associated with ore deposits. Nonetheless, no large ore deposits have been found within the igneous rocks of the Carrizos. Small deposits of uranium

Uranium

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

 plus vanadium

Vanadium

Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...

 and of copper

Copper

Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 plus silver

Silver

Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...

 have been found in the sedimentary rocks of the Morrison Formation

Morrison Formation

The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is 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, siltstone and limestone and is light grey, greenish...

in this mountain range.