amboy crater

A had told me about a geology field trip he had made to Amboy Crater, maybe a year or so ago, where he and his classmates explored and studied the remains of an extinct cinder cone volcano from 6,000 years ago. He expressed how he wanted to go back and search for volcanic "lava bombs" that are formed when a volcanic eruption blasts molten rock out into the air that cools and solidifies before landing on the ground. I was totally intrigued by this new knowledge of lava bombs, so I told him when he makes that trip that I want to come along and find some, too.

So, months (almost a year?) after this conversation this past Sunday we drove three hours out, 80 miles southeast of Barstow to Amboy, CA - one of us mildly suffering from a head cold/sinus irritation, and the other narrowly having escaped a potential hangover from the night before. We stopped for gas and a quick breakfast in Barstow, and in no time at all made it to the crater at 11:00 am. The sun was bright, the day clear and cold, and we immediately embarked on the trail through the basaltic lava fields surrounding the crater after hatching a game plan.

The game plan consisted of: hiking to the crater, traversing the rim, going back to the car to have our picnic lunch, going back out to the crater to hunt for lava bombs...but as time passed the plan changed organically, for the better.

The center of the crater - the white spots denote the lowest points of the lava lakes in the chasm. 

A jolt of chartreuse amongst the brown, terra cotta, black, white and grey colors of the earth immediately made itself known upon viewing. I believe this is Rhizocarpon geographicum (map lichen) which supposedly thrives in mountainous areas of low air pollution.

Sifting through volcanic gravel, because it has an amazing crunchy texture and sound. All throughout the hike I enjoyed the sharp, tinkling sound of the rocks crunching on one another and under our feet. It almost sounded like broken porcelain, or something equally beautiful and devastating. And devastating it totally is, when you slip and fall onto said jagged edges of rock...heh.

A fine example of pāhoehoe lava (what I learned as "ropy" lava in a Rocks and Minerals book from the Eyewitness Explorers series that I read obsessively as a child) - see the soft folds of rock??

And conversely this is ʻaʻā lava ("stony rough lava") that is super jagged and makes that wonderful clinking sound. Awesome to behold, scary to accidentally slip and fall upon. I would carry around a lump of ʻaʻā for self defense, but I would most likely hurt myself with it before hurting anyone else...

There were definitely lava bombs here! After we walked all around the rim and were heading back out through the breach, I stopped and picked up a funny rounded, tadpole-looking rock. I asked A "What's this?" and he goes "Oh my GOSH, you found one!" It isn't pictured here, but it had a bit of a tail, which is evidence of the aerodynamic path the rock traveled before hitting the ground. So this basically sparked a massive Easter egg hunt for lava bombs for us, as we traced the ancient lava river beds, keeping our eyes peeled for funny-shaped rocks. An older couple asked A "You are...exploring?" and he answered with an emphatic "Yes!"

But of course I stopped to pick up rocks without any geological significance, based on color, shape, and texture. A made me laugh a lot during the hunt, for he would pick up a rock and explain to me why it is awesome, then basically chuck it unceremoniously away as his eyes roved on over to the next patch of rocks.

In conclusion, the plan pretty much turned into hike and hunt for lava bombs until we get hungry, which was perfect, because it was three miles or so back to the car - and eating, going back to the crater, then walking back to go home didn't make much sense at all anyway. As the wind whipped up a chill, we prepared and enjoyed a massive sushi lunch in the cozy warmth of the truck, which was an adventure unto its own, after a full day of exploring and rock hounding.