|File:Badwater Basin from Dante's View Overlook.JPG|
Inyo County, California
|Primary inflows||Amargosa River|
|Primary outflows||Terminal (evaporation)|
|Basin countries||United States of America|
|Max. length||7.5 miles (12 km)|
|Max. width||5.0 miles (8 km)|
|Surface elevation||−279 feet (−85 m)|
|References||U.S. Geological Survey Geographic Names Information System: Badwater Basin|
Badwater Basin is an endorheic basin in Death Valley National Park, Death Valley, Inyo County, California, noted as the lowest point in North America, with an elevation of 282 ft (86 m) below sea level. Mount Whitney, the highest point in the contiguous 48 United States, is only 84.6 miles (136 km) to the north west.
The site itself consists of a small spring-fed pool of "bad water" next to the road in a sink; the accumulated salts of the surrounding basin make it undrinkable, thus giving it the name. The pool does have animal and plant life, including pickleweed, aquatic insects, and the Badwater snail.
Adjacent to the pool, where water is not always present at the surface, repeated freeze–thaw and evaporation cycles gradually push the thin salt crust into hexagonal honeycomb shapes.
The pool is not the lowest point of the basin: the lowest point (which is only slightly lower) is several miles to the west and varies in position, depending on rainfall and evaporation patterns. The salt flats are hazardous to traverse (in many cases being only a thin white crust over mud), and so the sign marking the low point is at the pool instead. The basin was considered the lowest elevation in the Western Hemisphere until the discovery of Laguna del Carbón in Argentina at −344 ft (−105 m).
At Badwater Basin, significant rainstorms flood the valley bottom periodically, covering the salt pan with a thin sheet of standing water. Newly formed lakes do not last long though, because the 1.9 in (48 mm) of average rainfall is overwhelmed by a 150 in (3,800 mm) annual evaporation rate. This is the greatest evaporation potential in the United States, meaning that a 12 ft (3.7 m) lake could dry up in a single year. When the basin is flooded, some of the salt is dissolved; it is redeposited as clean crystals when the water evaporates.
The current best understanding of the area's geological history is that the entire region between the Colorado River in the east and Baja California in the southwest (and bordered by various uplifts and mountains around the west-northwest-northern perimeters) has seen numerous cycles since at least the start of the Pleistocene (and perhaps up to 3 Ma) of pluvial lakes of varying size in a complex cycle mainly tied to changing climate patterns (particularly, glaciation during the numerous recent Ice Ages), but also influenced by the progressive depositing of alluvial plains and deltas by the Colorado River (cf. Salton Sea), alternating with periodic water body breakthroughs and rearrangements due to erosion and the proximity of the San Andreas Fault. This has resulted in a high number of evaporating and reforming endorheic lakes throughout the Quaternary Period in the area, with an intertwined history of various larger bodies of water subsuming smaller ones during water table maxima and the subsequent splitting and disappearance thereof during the evaporative part of the cycles. Although these local cycles are now somewhat modified by human presence, their legacy persists; despite appearances much to the contrary, Death Valley actually sits atop one of the largest aquifers in the world.
Throughout the Quaternary's wetter spans, streams running from nearby mountains filled Death Valley, creating Lake Manly, which during its greatest extents was approximately 80 mi (130 km) long and up to 600 ft (180 m) deep. Numerous evaporation cycles and a lack of outflow caused an increasing hypersalinity, typical for endorheic bodies of water. Over time, this hypersalinization, combined with sporadic rainfall and occasional aquifer intrusion, has resulted in periods of "briny soup", or salty pools, on the lowest parts of Death Valley's floor. Salts (95% table salt – NaCl) began to crystallize, coating the surface with the thick crust, ranging from 3 to 60 in (8 to 152 cm), now observable at the basin floor.
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