Skip to main content
U.S. flag

An official website of the United States government

Multimedia

Images

A geologist crouches next to a rhyolite outcrop and points to an egg-shaped mass of radiating pink minerals about the size of a cantaloupe. The rest of the rock is pocked with other egg to grapefruit sized pink crystal masses, interspersed with chunky fragments of black glassy lava.
Large spherulites in Hot Creek rhyolite lava in the Long Valley Caldera
Large spherulites in Hot Creek rhyolite lava in the Long Valley Caldera
A geologist crouches next to a rhyolite outcrop and points to an egg-shaped mass of radiating pink minerals about the size of a cantaloupe. The rest of the rock is pocked with other egg to grapefruit sized pink crystal masses, interspersed with chunky fragments of black glassy lava.

Large spherulites in Hot Creek rhyolite lava in the Long Valley Caldera

Large spherulites in Hot Creek rhyolite lava in the Long Valley Caldera

The presence of spherulites indicates that a lava flow cooled quickly, and their mineralogy holds clues to its precise cooling history. USGS photo by Jessica Ball

By
California Volcano Observatory, California Volcano Observatory, Long Valley Caldera
A geologist crouches next to a rhyolite outcrop and points to an egg-shaped mass of radiating pink minerals about the size of a cantaloupe. The rest of the rock is pocked with other egg to grapefruit sized pink crystal masses, interspersed with chunky fragments of black glassy lava.

Large spherulites in Hot Creek rhyolite lava in the Long Valley Caldera

Large spherulites in Hot Creek rhyolite lava in the Long Valley Caldera

The presence of spherulites indicates that a lava flow cooled quickly, and their mineralogy holds clues to its precise cooling history. USGS photo by Jessica Ball

By
California Volcano Observatory, California Volcano Observatory, Long Valley Caldera
A broad, flat plain covered in dull green sagebrush stretches away from the viewer in this panorama. The photo is being taken from a rocky hill, with snow-capped, sharp peaks on the far side of the plain and low raised hills on the right side of the photo. One geologist is sitting on the rocks at lower right and one geologist is standing and giving a peace sign.
Panoramic view of the Long Valley Caldera from its north side
Panoramic view of the Long Valley Caldera from its north side
A broad, flat plain covered in dull green sagebrush stretches away from the viewer in this panorama. The photo is being taken from a rocky hill, with snow-capped, sharp peaks on the far side of the plain and low raised hills on the right side of the photo. One geologist is sitting on the rocks at lower right and one geologist is standing and giving a peace sign.

Panoramic view of the Long Valley Caldera from its north side

Panoramic view of the Long Valley Caldera from its north side

This panorama of the Long Valley Caldera, looking from north to south, shows its broad central plain, post-caldera rhyolite flows and uplift on the right, and eastern Sierra Nevada in the background. USGS photo by Jessica Ball.

By
California Volcano Observatory, California Volcano Observatory, Long Valley Caldera
A broad, flat plain covered in dull green sagebrush stretches away from the viewer in this panorama. The photo is being taken from a rocky hill, with snow-capped, sharp peaks on the far side of the plain and low raised hills on the right side of the photo. One geologist is sitting on the rocks at lower right and one geologist is standing and giving a peace sign.

Panoramic view of the Long Valley Caldera from its north side

Panoramic view of the Long Valley Caldera from its north side

This panorama of the Long Valley Caldera, looking from north to south, shows its broad central plain, post-caldera rhyolite flows and uplift on the right, and eastern Sierra Nevada in the background. USGS photo by Jessica Ball.

By
California Volcano Observatory, California Volcano Observatory, Long Valley Caldera
Eddy covariance station at Mammoth Mountain, California
Eddy covariance station at Mammoth Mountain, California
Eddy covariance station at Mammoth Mountain, California
Eddy covariance station at Mammoth Mountain, California

Eddy covariance station at Mammoth Mountain, California

Eddy covariance station at Mammoth Mountain, California

Photograph of permanent eddy covariance station installed since 2014 in area of volcanic CO2 emissions on Mammoth Mountain, California. USGS photo by Jennifer Lewicki, August 2019.

By
Volcano Science Center, California Volcano Observatory, Yellowstone Volcano Observatory, California Volcano Observatory, Long Valley Caldera, Mammoth Mountain
Eddy covariance station at Mammoth Mountain, California

Eddy covariance station at Mammoth Mountain, California

Eddy covariance station at Mammoth Mountain, California

Photograph of permanent eddy covariance station installed since 2014 in area of volcanic CO2 emissions on Mammoth Mountain, California. USGS photo by Jennifer Lewicki, August 2019.

By
Volcano Science Center, California Volcano Observatory, Yellowstone Volcano Observatory, California Volcano Observatory, Long Valley Caldera, Mammoth Mountain
A two part figure with a shaded-relief map view of the Long Valley Caldera marked with the outlines of its resurgent dome, Mammoth Mountain, Crowley Lake, the caldera outline, and major roads. Below is a west-to-east cross-section cartoon of the caldera, showing the locations of these features as well as the depth of caldera fill, basement rocks, and the paths of cold and hot water near magmatic intrusions.
Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera.
Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera.
A two part figure with a shaded-relief map view of the Long Valley Caldera marked with the outlines of its resurgent dome, Mammoth Mountain, Crowley Lake, the caldera outline, and major roads. Below is a west-to-east cross-section cartoon of the caldera, showing the locations of these features as well as the depth of caldera fill, basement rocks, and the paths of cold and hot water near magmatic intrusions.

Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera.

Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera.

Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera. The resurgent dome, Doe Ridge, Mammoth Mountain, and the Inyo Craters and Domes all reflect volcanic activity since 760,000 years ago, when a giant eruption formed the caldera.

By
Volcano Hazards Program, California Volcano Observatory, California Volcano Observatory, Long Valley Caldera
A two part figure with a shaded-relief map view of the Long Valley Caldera marked with the outlines of its resurgent dome, Mammoth Mountain, Crowley Lake, the caldera outline, and major roads. Below is a west-to-east cross-section cartoon of the caldera, showing the locations of these features as well as the depth of caldera fill, basement rocks, and the paths of cold and hot water near magmatic intrusions.

Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera.

Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera.

Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera. The resurgent dome, Doe Ridge, Mammoth Mountain, and the Inyo Craters and Domes all reflect volcanic activity since 760,000 years ago, when a giant eruption formed the caldera.

By
Volcano Hazards Program, California Volcano Observatory, California Volcano Observatory, Long Valley Caldera
A simplified geologic map of the Long Valley Caldera, showing post-caldera rhyolite lava flows in various colors, concentrated on the W half of a long ellipsoidal caldera. The topographic caldera margin is shown in part with a dashed line surrounding the lavas and the structural caldera margin (ring fault), shown with a dotted line.
Long Valley Caldera map
Long Valley Caldera map
A simplified geologic map of the Long Valley Caldera, showing post-caldera rhyolite lava flows in various colors, concentrated on the W half of a long ellipsoidal caldera. The topographic caldera margin is shown in part with a dashed line surrounding the lavas and the structural caldera margin (ring fault), shown with a dotted line.

Long Valley Caldera map

Long Valley Caldera map

Map showing distribution of Long Valley postcaldera rhyolites. Abbreviations: CD, Casa Diablo geothermal plant; Ski area, Mammoth Mountain Ski Area; LVEW, Long Valley Exploratory Well, 3 km deep, located high on resurgent uplift; s, surficial deposits filling structural lows on resurgent uplift.

By
California Volcano Observatory, California Volcano Observatory, Long Valley Caldera
A simplified geologic map of the Long Valley Caldera, showing post-caldera rhyolite lava flows in various colors, concentrated on the W half of a long ellipsoidal caldera. The topographic caldera margin is shown in part with a dashed line surrounding the lavas and the structural caldera margin (ring fault), shown with a dotted line.

Long Valley Caldera map

Long Valley Caldera map

Map showing distribution of Long Valley postcaldera rhyolites. Abbreviations: CD, Casa Diablo geothermal plant; Ski area, Mammoth Mountain Ski Area; LVEW, Long Valley Exploratory Well, 3 km deep, located high on resurgent uplift; s, surficial deposits filling structural lows on resurgent uplift.

By
California Volcano Observatory, California Volcano Observatory, Long Valley Caldera
banding of Panum pumice and obsidian
Flow banding of Panum pumice and obsidian
Flow banding of Panum pumice and obsidian
banding of Panum pumice and obsidian

Flow banding of Panum pumice and obsidian

Flow banding of Panum pumice and obsidian

Flow banding of Panum pumice and obsidian of the same composition.

By
Volcano Hazards, California, California Volcano Observatory, Long Valley Caldera
banding of Panum pumice and obsidian

Flow banding of Panum pumice and obsidian

Flow banding of Panum pumice and obsidian

Flow banding of Panum pumice and obsidian of the same composition.

By
Volcano Hazards, California, California Volcano Observatory, Long Valley Caldera
View All