The Rawson Mountains are a mountain range in

Riverside County Riverside County is a county located in the southern portion of the U.S. state of California. As of the 2020 census, its population was 2,418,185, making it the fourth-most populous county in California and the 10th-most populous in the Unit ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. The Rawson Mountains are located south of the

Diamond Valley Lake Diamond Valley Lake is a man-made off-stream reservoir located near Hemet, California, United States. It is one of the largest reservoirs in Southern California and one of the newest. It has a capacity of . The lake nearly doubled the area's s ...

, southeast of Domenigoni Valley, east of French Valley, west of Goodhart Canyon and north of Bachelor Mountain, Auld Valley (above

Lake Skinner Skinner Reservoir, also known as Lake Skinner, is a reservoir in western Riverside County, California, located at the foot of Bachelor Mountain in the Auld Valley, approximately northeast of Temecula. It was created in 1973 by the construction ...

) and Black Mountain.USGS Topographic Map Quadrants
Winchester, CA Hemet, CA Bachelor Mountain, CA
an
Sage, CA
/ref> The Rawson Mountains are composed primarily of

metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...

rock of the

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

French Valley formation, formed as a roof pendant of the Peninsular Range Batholith. The extreme western end of the range and various intrusions within it are

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 ...

granitic A granitoid is a broad term referring to a diverse group of coarse-grained igneous rocks that are widely distributed across the globe, covering a significant portion of the Earth's exposed surface and constituting a large part of the continental ...

rock. Cris Goetz, Ray Brainard, Jill Carlson, Kerry Cato, Norm Holst, Dan Johnson, Don Riley and Martin Siem, ''Geology of the Eastside Reservoir Project, Riverside County, California'', Water for Southern California: Water Resources Development at the Close of the Century, San Diego Geological Soc, San Diego, Dec 1, 1999, p.47
/ref> Crown Valley in the midst of the range is drained to the south by Rawson Canyon Creek into Tucalota Creek before it enters Lake Skinner. Its western and northern slopes drain into Warm Springs Creek watershed of the

Santa Margarita River The Santa Margarita River which with the addition of what is now Temecula Creek, was formerly known as the Temecula River, is a short intermittent river on the Pacific coast of Southern California in the United States, approximately U.S. Geolog ...

, or the reservoir. To the northeast the drainage is into the eastern Diamond Valley and the San Jacinto River.

References

Mountain ranges of Southern California Mountain ranges of Riverside County, California Peninsular Ranges {{RiversideCountyCA-geo-stub