The Plomosa Mountains are a mountain range in

La Paz County, Arizona La Paz County is the 15th county in the U.S. state of Arizona, located in the western part of the state. As of the 2020 census, its population was 16,557, making it the second-least populous county in Arizona. The county seat is Parker. Th ...

, running generally south of

Bouse, Arizona Bouse ( ''rhymes with "house"'') is a census-designated place (CDP) and ghost town in La Paz County, Arizona, United States. Founded in 1908 as a mining camp, the economy of Bouse is now based on tourism, agriculture, and retirees. The populatio ...

near the Arizona/California border.

Quartzsite Quartzsite is a town in La Paz County, Arizona, United States. According to the 2020 census, the population was 2,413. Interstate 10 runs directly through Quartzsite which is at the intersection of U.S. Route 95 and Arizona State Route 95 wi ...

lies to the west across the

La Posa Plain The La Posa Plain is a wide, generally flat plain in western Arizona near the Colorado River and is on the west and northwest border of the Kofa National Wildlife Refuge. The plain lies to the east of the Colorado River Indian Reservation and east ...

. The

Harcuvar Mountains The Harcuvar Mountains (Yavapai: Ahakuwa) are a narrow mountain range in western-central Arizona, United States. The range lies just east of the north-south Colorado River, and south of the east-west, west-flowing Bill Williams River, from Alamo ...

and

Little Harquahala Mountains The Little Harquahala Mountains are a small, arid, low-elevation mountain range of western-central Arizona, in the southeast of La Paz County. The range is northwest-by-southeast-trending and is in a region of about thirty landforms, plains, val ...

lie to the east across the Ranegras Plain. The

New Water Mountains The New Water Mountains is a mountain range in southwestern Arizona. The range is on the northern border of the Kofa National Wildlife Refuge as well as the northern Kofa Mountains. It is a northwest–southeast trending range, about long. T ...

lie to the southeast beyond Black Mesa.

Interstate 10 Interstate 10 (I-10) is the southernmost cross-country highway in the American Interstate Highway System. I-10 is the fourth-longest Interstate in the United States at , following I-90, I-80, and I-40. This freeway is part of the originally pl ...

crosses the center of the range. The Plomosa ghost town and mining camp lie on the southwest side of the range. Evidence of both

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

ing and

strike-slip faulting In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

is present in the Plomosa Mountains.F.K. Miller and E.H. McKee, "Thrust and Strike-Slip Faulting in the Plomosa Mountains, Southwestern Arizona". GSA Bulletin, March 1971 (fee required for full text).
/ref> The highpoint of the range is Black Mesa (La Paz County) in the southern regions. Ibex Peak is a highpoint in the north.

References

{{Coord, 33.700, -114.051, type:landmark, display=title Mountain ranges of the Sonoran Desert Mountain ranges of the Lower Colorado River Valley Mountain ranges of La Paz County, Arizona Mountain ranges of Arizona