Few places in the United States contain as much geological diversity as California’s Mono County. While its many mountains and valleys prominently showcase the processes shaping our earth’s crust, the Mono Basin captivates one’s imagination with dramatic evidence of its volcanic nature.
This region boasts the youngest volcanic chain in North America, with eruptions as recent as 300 years ago. The volcanism is still active today, as countless geothermal sites across the basin demonstrate.
Below are just a few prominent features you can get up close and personal with, but we encourage you to share your experiences and favorite spots as well. Anyone can contribute directly to Natural Atlas, record trips, or share online @NaturalAtlas on Twitter or @naturalatlas on Facebook.
Black Point Fissures
On the north shore of Mono Lake, the Black Point Fissures offer a rare terrestrial view into the results of an underwater eruption. It may be the only fully exposed underwater volcano on earth. The fissures themselves form a network and vary greatly in size, from inches to multiple feet wide and 50 or more feet deep.
The fissures are reachable from the Black Point Fissures Trailhead via an easy 0.9 mile hike along Black Fissures Trail. The elevation of Black Point itself also provides sweeping views back toward Mono Lake, Negit Island, and Paoha Island.
As young as 600 years, Panum Crater is a near perfectly preserved rhyolitic lava dome that didn’t fully refill during the last eruption, leaving an exposed rim. It’s the most accessible feature within the Mono Craters chain.
The entire rim can be hiked via the looping 1.5 mile Rim Trail, exposed and consisting of loose pumice. The shorter Plug Trail takes you to the top of the plug dome itself, also across loose footing. Both offer incredible views of the Eastern Sierra, Mono Lake, and Mono Craters.
The Inyo Craters are a southern continuation of the same chain as Mono Craters, though formed over a shorter period of time and by eruptions of lower-silica rhyolite than their northern neighbors. The most accessible examples are South Inyo Crater and North Inyo Crater, both containing small lakes at the bottom of their 600 foot wide and 200 foot deep craters.
The looping Inyo Craters Trail is approximately half a mile each way and relatively easy. It takes you by an observation area on the southern crater with clear views of its turquoise waters, then to the more obscured northern dome. In the winter, access is via the Inyo Craters Ski Trail.
Incredibly rare geological conditions occurred 80,000 years ago to slowly cool a lava flow of uniform mineral composition. The result was a formation of hexagonal columns, standing vertically in many areas and exposing a tile-like pattern from their tops.
The exposed lava columns are reachable after an easy half mile hike from Devils Postpile Trailhead along the Devils Postpile Boundary Trail. If you are able to hike an additional two miles each way, Rainbow Falls is a beautiful added bonus. Take the trail from Devils Postpile south past its intersection with the John Muir Trail, then continue onto the Lower Rainbow Falls Trail.
Hot Creek Geologic Site
For evidence of the area’s continuing volcanism, head to the Hot Creek Geologic Site to witness a variety of geothermal activity. Powered by magma chambers three miles below, the site is home to pools of boiling water, fumaroles, and occasional geyser eruptions. The Mono Basin is home to numerous geothermal sites, but these bubbling turquoise ponds are the most accessible on public land.
The interpretive trail provides a short, paved path down to Hot Creek. Entering the water is prohibited and extremely dangerous, as the occasional geyser activity can alter temperatures by 200°F almost instantly.
Overlooking Mono Basin
For an experience that doesn’t require hiking, the small Mono Lake Overlook pullout from US-395 at the basin’s northern approach offers one of the best views of the region. Just take in the sight of Mono Lake, Mono Craters, and the entire northern basin, or explore more context through an array of interpretive signs on site.
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