Friday, May 31, 2013

From a Land of Riches to the Barrens: The Basin and Range

We set off early today on our journey of exploration on the Colorado Plateau, but to get to the plateau we needed to travel nearly 500 miles from California's Great Valley to Las Vegas, passing through some of the loneliest landscapes to be found in the United States. I couldn't help but notice how we also passed from a land flowing literally with milk and honey (dairy farms and beekeepers among the thousands of farms) to a barren landscape where life must be grasped and fought for. We crossed Tioga Pass, which despite the frighteningly dry year was still mantled with some snowfields, and into the Basin and Range Province east of the Sierra Nevada. The difference was striking.
The Basin and Range Province happened because a high plateau-like region with rivers extending from at least central Nevada to the Pacific was stretched to the breaking point. About 29 million years ago, the subduction zone that had dominated the tectonic history of the Western United States for nearly 180 million years was destroyed by a process that resulted in the formation of the San Andreas fault. The crusted extended and broke into numerous fault block mountains (horsts) and deep fault valleys (grabens). The Sierra Nevada was the largest and highest of these fault blocks and as a consequence, the mountains prevent most of the rain and snow from ever reaching the lands to the east.

The Sierra Nevada is the realm of the cool dark forests and the high glaciated peaks. The Basin and Range is a place where sagebrush reigns, and practically the only trees are dumpy little pinyon pines and juniper. It's a hard dry land. We crossed Montgomery Pass into Nevada and had a close look at Boundary Peak, which at 13,147 feet (4,007 m), is the highest point in Nevada. Ironically it is not the highest peak in the mountain range in which it is situated. Adjacent Montgomery Peak is 13,441 feet (4,097 m) tall, but as the name suggests, the state boundary falls between the two. A bit farther south, White Mountain Peak soars to 14,252 ft (4,344 m), the third highest peak in California.
It's a hard land, but that doesn't mean that life doesn't thrive. We were lucky to see some members of the Montgomery Pass herd of wild horses right next to the highway. Horses came to America with the Spaniards in the 1500s and escapees over the centuries formed naturalized herds across the west. In a sense though, these horses are returnees to a long-lost homeland. The horses evolved in North America, and migrated to Asia over the Bering Land Strait, but about 12,000 years ago they became extinct in the land of their origin.
I took a new road today, the highway through Dyer and Fish Lake Valley. It is a beautiful place, and few hundred ranchers and farmers make a living off the small streams that flow off the White Mountains and from the copious amounts of Pleistocene groundwater that lies hidden beneath the valley floor (a nonrenewable resource though; they're using up the water that arrived there during the Ice Ages).
Others tried to wrest life from the land, but in a different way. When the California Gold Rush petered out in the 1850s, hungry miners scoured the lands to the east for the next great Mother Lode. Their searches were most often futile, but a few rich mines were discovered (such as the Comstock Lode), and other towns were built on dreams of avarice, but not much more. Such was the fate of Palmetto in western Nevada. There are only a few structures remaining, carved out of the rhyolite tuff that covers much of the region. For a time, several hundred miners pitched camp here, looking for plays of valuable minerals in the rocks, but they found little and quickly abandoned the site.
The desert has reclaimed much of the old town, except a few buildings which stand only because...well, I don't know how the wall below is still standing.
The miners could look out a window and see the sometimes snow-capped summit of White Mountain Peak in the distance, dreaming of water and riches, but having neither. A barren land, yes, but rich in other ways. The geology exposed in these barren mountains is fascinating, and volcanoes and earthquakes show that the crust here is still very active.

This is one of my favorite regions on the planet...
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