Saturday, March 10, 2018

How Low Can You Go? Badwater Basin, and a Real Hell on Earth


Salt flats at Badwater, -282 feet. The snowcapped mountain in the distance is Telescope Peak, 11,049 feet.



How bad could it be? On our recent trip to Death Valley, we made the rather mandatory pilgrimage to Badwater, the lowest point in North America at -282 feet (86 meters). Although the hottest temperature ever recorded on planet Earth was measured at Furnace Creek Ranch in 1913 (56.7°C; 134°F), it is known that Badwater is often 2 degrees hotter. That's hot. Really hot.
I've regularly worked and played in temperatures as high as 105°F without ill effect at home in the Great Valley of California. I floated down the Colorado River in August of 2013 where temperatures soared as high as 118°F, and I realized that I could have been in trouble if we didn't have the river to dip in every few minutes (because it flowed from deep within Lake Powell, the water temperature was around 48°F even many miles downstream). The hottest moment I've ever experienced was in the aforementioned Death Valley when we had an occasion to be there in late May, and an early heat wave shot temperatures to a near record 122°F. It was simply intolerable outdoors...we retreated to the motel room until the sun went down before emerging to seek dinner. People no doubt adapt to such conditions, but it can't be pleasant.
Alluvial fan just south of Badwater. The terraces on the fan are fault scarps, indicating the role of faulting in the subsidence  of Death Valley.




Standing at the lowest point in North America does cause one to consider other low places on the planet. The National Park Service provides a handy guide on interpretive signs and on their websites. They note that all of the low places also tend to be exceedingly dry and hot, and that the source of the low elevation is generally tectonic in origin. Those low points are as follows:
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 Carbón (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)
The Black Mountains provide the backdrop to Badwater. They rise steeply more than a mile above the salt flats.




Looking at this list, it is clear that the Dead Sea is in a class by itself as far as low elevations are concerned. At nearly 1,400 feet below sea level, it is unique in the world. To find anything deeper, we have to reach back into the depths of geologic time. The Strait of Gibraltar is narrow and shallow, and is the only connection between the Mediterranean and any other ocean. What would happen if it ever separated the two oceans? It's not totally idle speculation...it turns out that this actually happened, about six million years ago. The speculation began when vast amounts of salt, gypsum and anhydrite deposits were discovered beneath the seafloor sediments of today's Mediterranean Sea.



When the cutoff occurred, the Mediterranean immediately began to dry up. And dried more. And then even more. The level of the sea dropped precipitously. It dropped past the 1,000 foot level. And then 2,000. And it kept going. Until the level of the basin reached 15,000 feet below sea level. Three miles below sea level. The implications are staggering in many ways. The Nile and Rhone Rivers would have started cutting deep channels far below their normal level. In places, the subsequent sedimentary layers hide canyons that were once 8,000 feet deep (The Grand Canyon, for comparison is 5-6 thousand feet deep). 
The climate changes would be extreme. Air sinking into the basin would increase temperatures at the dry adiabatic rate of 5.5°F per thousand feet. That amounts to conditions at the lowest reaches of the Mediterranean Basin that would be 70°F higher than they would be at sea level. In this desert environment, summertime temperatures could reach 176°F. No organisms could survive at these levels except for a few thermophiles. This is a place no human could or would be able to venture.



And imagine the end. Imagine the moment that the Atlantic Ocean began seeping over the Strait of Gibraltar. Seepage that turned into a torrent, and then a torrent that turned into a flood, and a flood that turned into a deluge beyond imagining. Some calculations suggest flows equivalent to 1,000 Amazon Rivers at once. The entire ocean basin could have filled in between a few months to two years. Sea level would have risen as much as 30 feet per day. This event is called the Zanclean Flood.

All in all, this place would have been hell on Earth, at least until the waters came...

PS: The Rhone River, not the Rhine. Correction made, thank you Olivier Malinur.
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