Geology
Mono County, CA
Approximate location — plotted from published sources, not a site visit, and not a guarantee of access.
Pair of mid-14th-century phreatic (steam-blast) explosion craters on Deer Mountain above Mammoth Lakes—~600 ft wide and 100–200 ft deep, each holding a small forest-ringed lake, formed when rising magma flashed groundwater to steam without extruding lava.
| Region | Mono County, CA |
|---|---|
| Coordinates (approx.) | 37.6887, -119.0057 |
| Unit | Inyo National Forest (USFS) |
| Origin | Phreatic craters ~1350 CE |
| Hike | Short loop from trailhead |
| Elevation | ~8,200 ft |
Public recreation data — BLM & Recreation.gov (RIDB). Verify current access, fees, and seasonal closures before traveling.
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Plan ahead. Leave no trace. Verify current access before traveling.