Volcanoes in the Mist (and underground): Travels in Death Valley

The Inyo Mountains, in any other setting in the world, would be considered a major mountain range, preserved as a national park perhaps, and celebrated as scenic wonderland. But just like an accomplished sibling overshadowed by a more famous brother or sister, the Inyos lie across the valley from the most spectacular part of the Sierra Nevada, and south of the higher White Mountains. For better or worse (mostly better), only a few roads penetrate the range, including the main western highway into Death Valley National Park, State Route 190. That was the road we followed on our recent exploration of Death Valley.

As was noted in the previous post, we attempted our trip during the Bombogenesis storm that wreaked havoc across Southern California. This kind of storm can often result in disaster as highways get closed or damaged by landslides, but we were lucky and were able cross the Inyo Mountains and Darwin Plateau without problems. But we did get the opportunity to see some great geology, and even were able to add a new stop to our itinerary (because we missed a different one, but I'm not complaining).

Our first sight as we approached the mountains was the snow covering the desert peaks (first picture above), a hint to the seriousness of the storm we were challenging. The tilted rocks are Paleozoic-aged (300-550 million years) limestone layers. They recall a time when California was very different, completely submerged under a shallow tropical sea. We would be seeing more of these fascinating rocks later on. The road crossed the flat uplands of the Darwin Plateau, and then plunged down a steep incline towards the Panamint Valley.

We actually had fog in this arid environment, since the clouds were crowding against the edge of the steep mountains. As we passed the Father Crowley Vista Point, the clouds briefly parted and we had a view into the deep gorge of Rainbow Canyon. At this point, the slopes and flats are covered with basaltic lava flows ranging in age from 8 to 4 million years old. The immediate question becomes, why volcanoes? Why right here?

In a sense, volcanism is possible almost anywhere on the planet. It's not that there is magma everywhere, but that a hundred miles beneath our feet there is a zone, the asthenosphere, where the rock is almost molten, but not quite (perhaps 5-10% liquid). To melt this rock and create volcanic activity would require raising the temperature (as happens at hot spots like Hawai'i), or releasing pressure (pressure keeps the rocks from melting in the same way that pressure cookers prevent water from boiling). There aren't any hot spots in the immediate vicinity, but the crust across the Basin and Range Province has been stretched and thinned, allowing pockets of basaltic magma to form and rise into the rocks above, often following fault zones to the surface.

Although we couldn't see it through the clouds, there are basaltic lavas across the Panamint Valley that are of the same age and the same exact composition as those at the vista point. In addition, the rocks across the deep valley have no obvious source (the picture below is from last year, a decidedly drier trip). The best explanation for these rocks is that the lavas flowed across an original surface that was later broken up by faulting when the Panamint Valley formed. Since the youngest volcanic rocks are just 4 million years old, the Panamint Valley is younger still. The Panamint Valley is more than a mile deep and 65 miles long! That's a lot of geologic activity in a short period of time.

Looking across the Panamint Valley towards Hunter Mountain. The dark rocks on the left summit area are identical to the rocks at Father Crowley Vista Point.

We made a stop along the road descending into the Panamint Valley to check out some spectacular exposures of the dikes and sills that once fed the eruptions of the basaltic lavas (most years we are in too much of a hurry to get a camping spot at Stovepipe Wells). The magma was following whatever weakness in the surrounding rock that could be exploited by the molten rock. In some cases, vertical fractures allowed the magma to rise, forming dikes. In other cases, the molten rock flowed between limestone layers, forming sills. This extraordinary roadcut (below) showed textbook examples of both kinds of intrusions in the same outcrop. The usually black basalt has been oxidized (rusted) to produce the strange reddish-brown color.

There's a saying that one should never blindly sit on the ground in the desert. There are just too many things with fangs, stingers, or spines. The barrel cacti were looking to grow quickly in these rare wet times!

We headed down the highway. We had reached Death Valley National Park, and we faced whatever Bombogenesis was going to throw at us...

Death Valley Days: The First Day - Racing the Wind (and the torrential downpours)

We actually left last night, but drove the length of the Central Valley in the dark to make today more interesting (trust me, it's better that way). We drove through an intense rainstorm, raced on ahead of it, and set up camp near Bakersfield, hunkering down to await the onslaught. It didn't come! It's not that there is no storm, it's huge. But it was tracking north, and not moving east, so we were dry all night, and had sun for most of the day.

First stop was in Neogene marine sediments at the south end of the Great Valley, which included an introduction to field geology and the idea of formations and environments of deposition (our students are mostly seeing geology in the field for the first time). How do you know a layer is marine? One clue is in the hand of the student above: fossils! Somehow, unsurprisingly, a place called Sharktooth Hill yielded up shark teeth (and a few fragments of seagoing mammals).

The second stop was one of California's wonderful state parks (threatened in the current budget mess): Red Rock Canyon State Park. The Neogene sediments here, 60 miles farther inland, are terrestrial in nature, suggesting that the shoreline of the Pacific Ocean was a lot farther east a few million years ago. The students worked at the idea dividing an outcrop into formations or members. The sun was shining, but we were beginning to realize that we were being stalked and pursued by ominous looking clouds on the horizon. So, like refugees in a disaster movie, we set off in the direction that seemed the least stormy: north.

In about 45 minutes we reached Fossil Falls. It isn't a place to find fossils, it's a place to search for Ice Age rivers that haven't existed for 12,000 years or more. The overflow from Pleistocene Owens Lake poured over the lip of a basalt cliff and formed a bizarre landscape of giant potholes and polished basalt. There was an ancient form of life present, but it was still living: fairy shrimp, surviving in a few drying pools at the bottom of some of the potholes.

There was also the evidence of the previous inhabitants of the region (below); they left behind shards of obsidian and some artwork, bragging of their exploits in hunting (or maybe hopeful thinking?)

The storm was intensifying to the north of us and from behind, and from the west. We turned east (which we were going to do anyway), and skirted the south end of Owens Lake. In the Ice Ages, it was hundreds of feet deep, and in modern times a lake 30 feet deep persisted with no outlet, but Los Angeles sealed the fate of the lake in the 1920s when they diverted the streams feeding into the Owens River and sent the water south.

The weather turned ever more ominous as we passed over the Inyo Mountains near old mining town of Darwin, but a thin beam of sunlight broke through the clouds and lit up a ridge of Paleozoic limestone along the crest of the mountains.

We careened down the Inyos into the Panamint Valley, driving right through the heart of a breached cinder cone in the process.

After being buzzed by an F-16 at only a few hundred feet, we crossed the bottom of Panamint Valley, and were treated with a marvelous view of Telescope Peak, which at 11,049 feet is the highest elevation in Death Valley National Park. We crossed Towne Pass in the Panamint Mountains (5,000 feet), and descended a vertical mile to our camp at Stovepipe Wells, elevation...0 feet. After spending an entire day worrying about the gigantic storm enveloping California, we had not had a single drop of rain. Looking at the weather radar, I don't think we will be so lucky tonight; a 100%chance of rain is in the forecast. We battened down the hatches, and snuggled in for a good night's sleep. Tomorrow the adventure continues!