Thursday, April 21, 2016

Traversing Dark Canyons Where the Mountains are Upside-down: Titus Canyon Road, Death Valley

This is lonely country. There are no outposts of civilization, no phone service, and a single thin gravel road winds through the complex of canyon narrows. This is the kind of country where canyons and peaks get named for the people who disappeared there, rather than for their discoveries.  It's been 110 years since prospector Morris Titus went missing while searching for supplies for his party. The canyon now bears his name.
The serpentine road that passes through the Grapevine Mountains by way of Titus Canyon was constructed to provide access to the town of Leadfield, but the mining venture never amounted to anything, and the town was abandoned in less than a year. The road was kept open when Death Valley was declared a national monument by President Herbert Hoover, and today it is one of the most popular backcountry roads in the park. But that doesn't make it any less spooky, especially when it is late in the day and the sun is setting low on the horizon.
In places, the canyon has cut 3,000 feet into the heart of the mountain range, and the preponderance of limestone cliffs gives the gorge a ruggedness reminiscent of the Grand Canyon in Arizona. The rocks are of similar age, dating from the Paleozoic Era. But Titus Canyon has an attribute that is missing in the Grand Canyon: the rocks here are upside down.
Let's get an explanation...

Death Valley and the Basin and Range Province are largely the result of extensional forces dating from the last 15-20 million years. The crust was stretched and broken up into horsts and grabens, and earthquakes today still mostly reflect the heritage of the intense stretching of the earth's crust. It wasn't always that way. For something like 200 million years, the region was  under the influence of compressional forces, courtesy of the massive subduction zone that once existed off the California coast (it still exists to the north as the Cascadia Subduction Zone). As the ocean crust sank beneath the edge of the North American continent, the rocks that had originally formed the passive continental margin were pushed skyward and intensely folded. In places the folds literally turned the rocks upside down.
That's the case in the western part of the Grapevine Mountains, which are crossed by the road through Titus Canyon. The rocks slope into the ground towards the east, but because they are inverted, driving west takes the traveler through younger and younger rocks. You can even see the fold itself, a recumbent anticline, in a few spots (see the picture below). The rocks in the foreground are upside down, while those on the far summit above are right-side up (although all of the rocks are tilted steeply).

Because the Death Valley graben has been sinking through time, the valley is deeper and more narrow towards the edge of the range, since the river gradient is steeper and erosion faster. The narrows of Titus Canyon are memorable, being barely wide enough to accommodate the vans. Most of the students got out and walked the last mile (in the dark), because the canyon is so scenic in the lower reaches.

The rocks we were walking through date back to more than 500 million years ago, to Cambrian time. They are part of the Bonanza King formation, a limestone unit that was deposited in a warm shallow sea along the edge of North America. The animals that lived here included trilobites, a diverse group of arthropods related to Horseshoe Crabs and believe it or not, pill-bugs (roly-poly to some of you). Some trilobites could roll up in the manner of pill-bugs. There were also coral-like archaeocyathids, an ancient animal that was one of the first groups to go extinct. Think of them as a failed experiment in early life (although they were widespread and very common for a time). Brachiopods were another group found as fossils in these rocks. They are bivalved animals like the clams, but their anatomy is more primitive than a clam, if that is possible. They achieved great diversity during the Paleozoic period, but only a few species persist in today's seas (the living species are sometimes called Lampshells). There were a great many other species living in the ancient seas, but few of them had hard shells, and were thus very rarely preserved as fossils.

It can sometimes be difficult to imagine the forces that are required to turn mountains upside-down, and it's even more impressive to realize that the deformation actually took place thousands of feet, even miles deep in the crust. There was once an earlier mountain range in this place that rose to great height as a result of the compression. The mountains eventually eroded to a fairly gentle plain, only to be disrupted by extensional forces in the last 20 million years, resulting the mountains that we see today only a few million years ago. Canyons like the lower end of Titus have formed only the last few hundred thousand years.
We walked the last few yards of Titus Canyon, and emerged at the top of the massive alluvial fan built by debris washing out of the narrows. After being in dark canyons for hours, the expansive views were a shock. Way out in the distance to the left was Tucki Mountain, and at the base was the only outpost of civilization for many miles, at Stovepipe Wells. Poor Morris Titus made it out of the canyon, but it was July, and he had no water. He was doomed. Sometimes we can forget how much technology can shield us from the harsh world. We unconcernedly jumped into the vans, hoping there would still be enough hot water in the showers, and that they still be serving dinner in the restaurant.
Titus Canyon is one of the premier adventures at Death Valley National Park. High clearance cars and SUVs are recommended, and it's always a good idea to travel with others. It may be a delightful exploration of a few hours, but things can go wrong, so it's good to be with friends (my favorite t-shirt in recent years came from Death Valley; it said "Bring a compass! It's always awkward when you have to eat your friends.")!

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