Saturday, March 22, 2014

Out of the Valley of Death: Hitting the Lowest of the Low, the Driest of the Dry, and the Hottest of the Hot

Just how low can one go? Just how far can people descend in life before they hit bottom? In Death Valley National Park, there is a precise answer: -282 feet, or -85.5 meters at a spot called Badwater. That's also the lowest you can go in North America, but if you look at the big picture, there are seven other places around the world where you can sink even lower:

Earth’s Lowest Elevations (Courtesy of the National Park Service)
  • Dead Sea (Jordan/Israel) -1360 feet (-414 m)
  • Lake Assal (Djibouti, Africa) -509 feet (-155 m)
  • Turpan Pendi (China) -505 feet (-154 m)
  • Qattara Depression (Egypt) -435 feet (-133 m)
  • Vpadina Kaundy (Kazakstan) -433 ft (-132 m)
  • Denakil (Ethiopia) -410 ft (-125 m)
  • Laguna del Carb√≥n (Argentina) -344 ft (-105 m)
  • Death Valley (United States) -282 ft (-86 m)
  • Vpadina Akchanaya (Turkmenistan) -266 ft (-81 m)
  • Salton Sea (California) -227 ft (-69 m)
  • Sebkhet Tah (Morroco) -180 ft (-55 m)
  • Sabkhat Ghuzayyil (Libya) -154 ft (-47 m)
  • Lago Enriquillo (Dominican Republic) -151 ft (-46 m)
  • Salinas Chicas (Argentina) -131 ft (-40 m)
  • Caspian Sea (Central Asia) -92 ft (-28 m)
  • Lake Eyre (Australia) -49 ft (-15 m)
I had this awesome idea! I bet no one has ever thought to take their picture here before!
As the park service notes, most of these lowest points have a few things in common: they are very dry, and the origin of their low altitude is tectonic. The Basin and Range Province of which Death Valley is part of has been described as "The Broken Land" by Frank DeCourten, and indeed it is: fault after fault breaks up the Earth's crust into high mountain ranges (horsts) and deep fault basins (grabens). Death Valley is the ultimate expression of the process with relief of 11,330 feet between Telescope Peak (11,049 feet) and Badwater (-282 feet). The highest point in the United States outside of Alaska, Mt. Whitney (14,505 feet), is only 76 miles away as the crow flies.

If erosion wasn't a thing that happened, Death Valley would be even deeper. The sand and gravel that fills the Death Valley graben extends to a depth of about 9,000 feet, meaning if the gravel weren't there, the total relief would be 4 miles!
Fault scarps interrupt the smooth surface of this alluvial fan just south of Badwater.
From Badwater, it's not hard to see the evidence of the tectonic activity that formed the vast trough. In the picture above, two fault scarps are visible cutting across the relatively smooth profile of the alluvial fan. The earthquakes that caused these scarps happened in the last few thousand years, but they look fresh because of the lack of erosion in the dry climate.

Did we mention that Death Valley is also the driest place in North America? Average rainfall here is less than two inches a year. The Sierra Nevada and the other mountains of the Basin and Range province are very effective rain shadows (orographic barriers). Badwater lies at the edge of the Death Valley salt pan, a 200 square mile flat surface covered by salt and other evaporite minerals. It is hard to imagine a place more inhospitable to life on the planet. There are a few salt tolerant plants that grow on the edges of the pan, but I've heard of nothing that lives in the interior areas (except maybe some microbes here and there?).

To stand on the salt flat and look off in all directions is a lesson in isolation. Were it not for the vehicles and the ice chests and water bottles parked over against the mountain, this would be a moment of great concern. If it weren't February and summertime instead the concern would be near panic. We can easily forget the harsh nature of this environment when we are largely insulated from it. Furnace Creek, about a dozen miles north of this location, recorded a temperature of 134 °F (57 °C) in 1913. With the dethroning of the improperly recorded temperature in Libya from 1922, this is the hottest officially recorded temperature in world history. The hottest overnight temperature ever recorded, was 107 °F (42 °C) on July 12, 2012. That day, the average temperature was 117.5 °F (47.5 °C), the world's hottest 24-hours on record.

We talked about the geology and got back into the vans and headed north, up the valley towards Furnace Creek.

As we drove towards camp, we had a look at the edge of the vast turtleback fault surface at Badwater that forms the Proterozoic core of the Black Mountains (in the picture above). The long smooth slope in the shadow on the right is just about all fault surface. The sunlit rocks in the center  and on the left have slid off the fault to the north. They are composed of Miocene volcanic rocks of the Artist's Drive Formation.

The sunlight was a pleasant surprise. For much of the day the skies had been overcast, but in the latest part of the afternoon, the clouds parted for a moment and the rocks glowed orange and gold. The sediments and flows of the Artist's Drive formation are colored by oxidation of various metals in the volcanic ash and tuff layers, and are striking in almost any conditions, but they are especially bright at sunset.

The sun disappeared into the clouds again and the harsh edges of the valley blurred as the evening arrived. We headed back to our camp at Stovepipe Wells.

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