Outdoor Adventures / Road Trips

Exploring the Coso Volcanic Field

Exploring the Coso Volcanic Field

I’m often fascinated by the stretch of highway halfway between Los Angeles and Mammoth Lakes Basin. Going north, it starts as a nondescript drive through miles of arid desert before the majestic peaks of the Eastern Sierra Nevada come into view. And it’s here, on a random turn-off from the highway, where one of the most seismically active regions in the country resides.

The Coso Volcanic Field is well known to drivers along Highway 395, even if they don’t realize they’re driving past it. Its most visible landmark, a dramatic maroon cinder cone dubbed Red Hill, can clearly be seen from the road.

As a highly active geothermal area, Coso is no stranger to earthquake swarms — strings of tremors that can strike in the hundreds in as little as a few days. The volcanic field is also home to basaltic lava flows, obsidian flows, rhyolite domes, cinder cones, geysers, and fumaroles (steam-emitting openings in the earth’s crust), most of which lie within the Naval Air Weapons Station China Lake. Access is restricted to passersby but one can walk right up to Red Hill, one of the youngest mountains in the state.

Cinder Road

Turning off Cinder Road, we drove across a beautiful lava flow and right along the edge of an ancient lake bed. Its sun-baked crust looked like a mosaic of tiles.

Driving along the edge of an ancient lake bed

Ancient lake bed

Sun-baked lake bed

Ancient lake bed in the Coso Volcanic Field

Coso Volcanic Field

Red Hill is believed to have formed during an eruption about 10,000 to 14,000 years ago. The cinder cone is composed primarily of scoria, a type of volcanic rock resembling pumice. By definition, cinder cones are steep, cone-shaped piles of volcanic debris, such as ash and hardened magma, built up around vents.

Driving up to Red Hill

Here the debris spills out around Red Hill in mounds of red, brown, and black volcanic flakes resembling sand — like the layered sand art you find in bottles — but up close they’re quite coarse.

Volcanic debris spilling out from the cinder cone

Red Hill in the Coso Volcanic Field

Mounds of red, brown, and black volcanic flakes form a sand-like texture

On either side of the cinder cone, remnants of volcanic rocks are scattered across the otherworldly red landscape. If I fell asleep and got whisked away to the Coso Volcanic Field, I might have believed I’d been transported to the surface of Mars. We were only a couple of miles off the highway but you’d never know it looking around the desolate terrain.

Coso Volcanic Field

An otherworldly landscape

Volcanic rocks

In spite of its eeriness, this part of Inyo County, California, is also one of the most serene and awe inspiring. The next time I come here, I’m climbing to the top of the cinder cone!

Red Hill cinder cone

About Author

I'm a plant lover, passionate road-tripper, and cookbook author whose expert advice and bestselling books have been featured in TIME, Outside, HGTV, and Food & Wine. The No-Waste Vegetable Cookbook is my latest book. Garden Betty is where I write about modern homesteading, farm-to-table cooking, and outdoor adventuring—all that encompass a life well-lived outdoors. After all, the secret to a good life is... Read more »


  • Melissa Lim
    November 6, 2023 at 4:10 pm

    Hi! Wow how beautiful. Have you been back since? Thinking about taking a trip to see this for myself next week!

  • David M. Kalus
    July 5, 2019 at 1:09 am

    I appreciate the photography too and the vistas that nowadays are assumed to be Mars primarily

  • Alexia Landa
    April 18, 2018 at 1:15 am

    Hi Linda, Thank you for sharing this. I”m planning a trip to Coso Volcanic Field in a few weeks and I’m unfamiliar with the area. Is the road there paved or is it mostly dirt road. If so, will I need a 4×4?

    • Linda from Garden Betty
      April 25, 2018 at 2:12 am

      You can make it there in a normal car. 🙂 It’s paved on the highway and packed dirt/gravel on the road to the volcanic field. Enjoy your trip!

  • Elva Hernandez
    January 21, 2017 at 4:10 am

    Hi Linda. We recently purchased a vacation home in California Hot Springs. I have wondered the source of the hot springs in the area. Is Coso possibly the origin? Thank you.

    • Linda from Garden Betty
      January 29, 2017 at 8:48 am

      There’s quite a bit of geothermal activity throughout the Sierra, so I’m not sure the exact origins of those particular hot springs.

  • Coso Indians
    December 18, 2016 at 4:15 pm

    Thank you for the perfectly composed photographs. Beautiful, very well done.

  • luluaroo
    November 3, 2015 at 11:50 am

    I have passed by Red Hill many times and for a year just guessed at it. I finally researched it and was blown away, lol. Just kidding. California is full of past volcanic activity and I love being able to live somewhere that has such diversity and interesting geology.

    • Linda Ly of Garden Betty
      November 3, 2015 at 3:21 pm

      I find this region so fascinating, especially all the thermal springs! (And not just the popular ones that people soak in.)


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