Long Valley Caldera California
The Bureau of Land Management (blm.gov) administers the region of Long Valley Caldera near Bishop and area in the Sierra Nevada mountains not far from the California - Nevada border.
Popular attractions on the west side of Long Valley Caldera at Crestview is a road leading up Glass Creek to Obsidian Dome, a spectacular volcanic glass formation. Glass Creek gets its name from the obsidian pebbles in its streambed.
On US 395 the grade near Crestview marks the northern rim of the Long Valley Caldera. Inyo obsidian domes (Inyo Domes) erupted about 600 years ago. Despite its name Mammoth Scenic Loop was built as an escape route for Mammoth Lakes in case of natural disasters such as earthquakes and volcanic eruptions. A dirt road leads to a parking area for Inyo Craters.
Mammoth Mountain is a volcano formed approx. 400,000 years ago, located on the rim of the Long Valley Caldera. Mammoth Mountain is both a winter ski resort attraction and summer mountain bike, hiking and outdoor paradise.
On the east side of Long Valley is the popular Hot Creek recreation area with hot springs which feed the creek.
Long Valley Caldera has shown sustained unrest since 1980 characterized by recurring earthquake swarms, inflation (dome-shaped uplift) of the resurgent dome, and increased levels of fumarolic activity accompanied by high concentrations of carbon dioxide (CO2) gas in the soils around Mammoth Mountain on the southwest margin of the caldera.
In the spring mule deer are sometimes seen by visitors to Long Valley, one of the world's largest calderas, approx. 19 miles long by 10 miles wide.
Formed by volcanic eruption 760,000 years ago this topographic depression next to Mammoth Mountain is completely bounded by faults. So huge was the explosion of the volcano the magma chamber under the now completely destroyed volcano was significantly emptied to the point of collapse. The collapse itself caused an even larger secondary eruption of pyroclastic ash that burned and buried thousands of square miles, blanketing much of the western part of what is now the United States.
The Department of Energy (under the auspices of Sandia Laboratory Research Well) studied geothermal energy development in the resurgent dome of Long Valley Caldera drilling core samples to learn: the petrology, fracture state, and pore fluids, the state of stress and to model present-day hydrothermal conditions.