Little Walker Caldera is a depression in the eastern

Sierra Nevada The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...

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 ...

that is adjacent to the

Sweetwater Mountains The Sweetwater Mountains (highest peak: Mount Patterson ) are a small mountain range in northern Mono County, California and western Lyon County, Nevada, separating the West Walker River from the East Walker River. Most of the range is only acce ...

. The caldera is very large, measuring about in diameter. The caldera is named for the Little Walker River.

U.S. Route 395 in California U.S. Route 395 (US 395) is a United States Numbered Highway System, United States Numbered Highway, stretching from Hesperia, California to the Canada–United States border, Canadian border in Laurier, Washington. The California portion o ...

crosses the Northern boundary of the caldera, just west of the Devil's Gate Pass.

California State Route 108 State Route 108 (SR 108) is a state highway in the U.S. state of California that runs from the Central Valley and across the Sierra Nevada via the Sonora Pass. It generally runs northeast from downtown Modesto near the SR 99/ SR 132 interchang ...

follows more of the northern boundary of the caldera. Little Walker Caldera last produced a major eruption about 9 million years ago. Andesitic lava and tuff from the series of three eruptive events are found several hundred feet thick as far away as Antelope Valley, Mono County, north, Bridgeport Valley to the south, and

Sonora Sonora (), officially Estado Libre y Soberano de Sonora (), is one of the 31 states which, along with Mexico City, comprise the Administrative divisions of Mexico, Federal Entities of Mexico. The state is divided into Municipalities of Sonora, 72 ...

to the wes

The lava flows near Sonora are readily visible from

and followed the gold-laden stream beds in the area. Rich placer gold deposits have been revealed by excavating the ancient stream beds that lie underneath the lava flows. The Little Walker Caldera is classified as extinct, although it continues to produce substantial hot spring activity and occasional earthquakes. Some parts of the Little Walker Caldera overlap the northernmost extent of the

Yosemite National Park Yosemite National Park ( ) is a List of national parks of the United States, national park of the United States in California. It is bordered on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The p ...

References

External links

Schweich.comGeoScienceWorldEurekalert.org
{{Coord, 38.3235, -119.4224, display=title Volcanoes of Mono County, California Volcanism of California Calderas of California Volcanoes of California Miocene calderas