| Las Guijas Mountains | |
|---|---|
  Las Guijas Mountains Las Guijas Mountains | |
| Highest point | |
| Elevation | 4,665 ft (1,422 m)[1] |
| Coordinates | 31°38′20″N111°22′7″W / 31.63889°N 111.36861°W /31.63889; -111.36861 |
| Dimensions | |
| Length | 11.7 km (7.3 mi) NW-SE[2] |
| Width | 3.7 km (2.3 mi) NE-SW |
| Area | 33 km2 (13 sq mi) |
| Geography | |
| Country | United States |
| State | Arizona |
| Region | Sonoran Desert |
| County | Pima County, Arizona |
TheLas Guijas Mountains are a small northwest–southeast trendingmountain range in southernPima County, Arizona. The range is approximately 12 kilometres (7.5 mi) long by 4 km (2.5 mi).[2] Surrounding ranges includes theCerro Colorado Mountains to the northeast, theTumacacori Mountains ofSanta Cruz County to the east, theSan Luis Mountains to the south and theBaboquivari Mountains across theAltar Valley to the west.Arivaca is immediately to the southeast and the old mining townsite of Las Guijas is in the wash just north of the range.[2]
The highest peak of the range with elevation of 4,665 feet (1,422 m) lies 8 kilometres (5.0 mi) northwest of Arivaca which is at 3,643 feet (1,110 m). Las Guijas Peak at 4,650 feet (1,417 m) lies just 4500 feet south of the highest.[1][3][4]
The name of the range came from 19th century Spanish miners referring tolas guijas forthe rubble as theplacer gold they were working occurred in thegravels orconglomerates along the stream valleys and gulches draining the range.[5]
The southwestern flank of the range in underlain by up to 980 feet (300 m) ofJurassic age ash falltuff ofrhyodacite composition known as thetuff of Pajarito named for thePajarito Mountains of Santa Cruz County to the southeast,[6] later referred to as the Cobre Ridge Tuff.[7] This tuff was sourced from theCobre Ridge caldera. The northwest end of Cobre Ridge lies around 4 miles (6.4 km) south of the Las Guijas range. Younger Jurassic or Cretaceous sandstone and other sediments occur above the tuff.[6]
The northeastern flank of the range is underlain by an intrusivegranite also of Jurassic age.[6]