- Little Walker Caldera
Little Walker Caldera is a depression in the eastern
Sierra Nevada that is adjacent to theSweetwater Mountains . The caldera is very large, measuring about convert|18|km|mi in diameter. The Little Walker Caldera is named for theLittle Walker River ; it is the river that is little, not the caldera.U.S. Route 395 in California crosses the Northern boundary of the caldera, just west of theDevil's Gate Pass .California State Route 108 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 3 eruptive events are found several hundred feet thick as far away as Antelope Valley, Mono County, California 20 miles North, Bridgeport Valley, California to the South, and
Sonora, California 60 miles to the west [http://www.panoramio.com/photo/8320803] . The lava flows near Sonora are readily visible fromCalifornia State Route 108 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.Refer to
Stanislaus Group volcanic rocks, Table Mountain, Sonora [http://www.panoramio.com/photo/8320803] , and theEureka Valley Tuff for more information on the emissions from the Little Walker Caldera eruptions.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 northern most extent of the
Yosemite (CA) National ParkScholarly discussion of the history of the Little Walker Caldera may be found at [http://www.schweich.com/geoCAMnoLittleWalkerCaldera.html] [http://geosphere.geoscienceworld.org/cgi/content/abstract/3/6/646] [http://www.eurekalert.org/pub_releases/2007-12/gsoa-dgm122007.php]
Wikimedia Foundation. 2010.