Just 650 years ago, the Mono Valley was boiling with volcanic activity. Today, geologists keep a watchful eye on the Mono Craters east of the Sierra Nevada, which are dormant though not extinct.
Exploring the steep and shifting slopes of the larger craters can be quite arduous; however, the smaller Panum Crater has developed trails on both the plug and rim.
While the Panum Crater Rim Trail provides great views of the surrounding area, Plug Trail takes geology enthusiasts on a tour of Panum Crater’s rhyolite plug dome, formed by viscous lava filling the vent instead of flowing away from it. Inside the crater, fields of obsidian, once massive spires, make for scenic, albeit difficult terrain.
From the base, the dome is a quarter of a mile walk on a soft, pumice trail. Reaching the dome is relatively easy, though the trail becomes quite technical once inside the plug.
The many divergent trails can become lost in an alien landscape of crumbling breccia, huge rocks pushed aside by each successive lava flow. Taking a detour to inspect obsidian striped with boudinage is well worth your time, though backtracking may be necessary if your chosen path suddenly disappears into a pile of glassy rubble. Scrambling over the plug debris is treacherous at best, and it can easily lead to rockslides and lost footing.
For expert guidance and fun geological insight, tag along on one of the free summer interpretive programs offered by the Mono Lake Committee.
Both the dirt road leading to Panum Crater (1N28) and Highway 120 are subject to closure during heavy snowfall. Verify current road conditions with CalTrans before your visit.