It’s a rocky situation at Glass Mountain, California

After talking about scenery,  lava tubes and caves, it’s time to show some rocks that really rock.  Volcanic rocks, that is.  In our first two blogs about the Lava Beds National Monument we explored the hidden world of the lava caves and the rugged surface encompassing the monument.  This time we highlight the naturally occurring volcanic glass – obsidian rock.  It’s a form of Rhyolite that has the highest content of silica.  It is a volcanic glass prized by Native Americans for making arrowheads, knives, spear points and other tools.

Obsidian
Is this really sharp?

Obsidian Roc kFile
A huge pile of Obsidian Rock

This excursion took us about 30 miles south of the Lava Beds as we continued our geologic adventure at Glass Mountain.

Glass Mountain has been designated a Special Interest Area in Modoc National Forest because of its geologic formations.  The area is a 4,210 acre lava flow of glassy black obsidian boulders ending suddenly in white pumice soil.  Wandering around at the top of  Glass Mountain, we encountered prehistoric obsidian mines along a glass flow and were amazed at the ancient quarry remains evident today.  Being there was kind of surreal and made us wonder what it must have been like when this amazing landscape was being formed.  Estimates are that the most recent flows of pumice and obsidian at Glass Mountain occurred less than 900 years ago.

Glass Mountain
Glass Mountain
Ancient Rock Quarries
Ancient Rock Quarries

We are not geologists or rock hounds, but this place rocks!

The drive took us through the Modoc National Forest were we also saw Ponderosa Pines for miles covered with lichens.

Lichens covering trunks of Ponderosa Pines

After wandering through the quarries we drove to Arnica Sink, a dry basin in which water-worn cobbles and pebbles are mixed with sub-angular boulders covered by a washed mantle of pumice.

Arnica Sink
Arnica Sink

Our final stop was at Medicine Lake, which was once the center of a volcano and is over 150 feet deep.  It was quite a beautiful day and only a few folks were enjoying the serenity and beauty surrounding the area.

Medicine Lake
Medicine Lake

Yellow Rabbit flowers were in full bloom and dotted the landscape with yellow and orange glow. Simply beautiful!

Yellow Rabbit Bloom


4 thoughts on “It’s a rocky situation at Glass Mountain, California

  1. Interesting…..love exploring such unique places. Lichens? Never heard of that before. You captured it beautifully. I’ve come to realize there’s more places on the “must see” list than I ever thought…..we better get started soon!

  2. Love your photos and certainly have this place on the list for next time. The rabbitbrush have been prolific this year, everywhere we went and the lichen are such an amazing shade of green. Safe travels. 🙂

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