Bristol Dry Lake
| Bristol Lake | |
|---|---|
 |
|
| Location |
Mojave Desert San Bernardino County, California |
| Coordinates | 34°27′44″N 115°40′26″W / 34.4622°N 115.6738°WCoordinates: 34°27′44″N 115°40′26″W / 34.4622°N 115.6738°W |
| Lake type | Endorheic basin |
| Primary outflows | Terminal (evaporation) |
| Basin countries | United States |
| Max. length | 23 km (14 mi) |
| Max. width | 20 km (12 mi) |
| Shore length1 | 70 km (43 mi) |
| Surface elevation | 183 m (600 ft) |
| Settlements |
Amboy, California Saltus, California |
| References | U.S. Geological Survey Geographic Names Information System: Bristol Lake |
| 1 Shore length is not a well-defined measure. | |
Bristol Lake is a dry lake in the Mojave Desert of San Bernardino County, California, 42 km (26 mi) northeast of Twentynine Palms.
Bristol Lake is located southeast of Amboy, California and U.S. Route 66, and is also south of Cadiz, California. Amboy Crater and the Bullion Mountains are to the west, and Old Woman Mountains to the east.
The lake is approximately 23 km (14 mi) long and 20 km (12 mi) at its widest point.
Geological Setting
Bristol Lake is located in San Bernardino Counties Mojave Desert. It is a Playa Lake in the Basin and Range Province and is the northernmost member of a northwest-southeast trending playa lake system that includes Cadiz Lake and Danby Lake.
Mineralogy
Bristol Lakes mineralogy is described as having a bullseye pattern of minerals with lithofacies consisting of halite at the center surrounded by mud, gypsum, and finally a sand flat playa margin. These minerals also have vertical lithofacies which resemble the horizontal facies stratification with gypsum occurring deeper in the playa followed by mud-halite and halite on top.
The mud lithofacies consists of thick detrital mud, and the halite lithofacies is defined by giant hopper shaped crystals. Gypsum occurs in large lenticular crystals throughout the playa but is mostly concentrated around the mud lithofacies. Gypsum crystal sizes increase toward the center of the playa.
Interpretation
Gypsum
Past studies have determined that the gypsum occurring in Bristol Lake precipitated displacively within the sediment where groundwater saturated with gypsum recharges around the mud lithofacies. This is supported by the geometry of the deposit and by chemical ldata, which suggests that water precipitating gypsum in the playa is more associated with groundwater than the brine at the basin center. large size of the gypsum crystals may be due to several reasons; inflow waters containing low Ca/SO4 ratios may result in large lenticular crystals, microorganisms have the potential to rework large lenticular crystals, high concentrations of NaCl in inflow waters can decrease nucleation density of minerals resulting in larger crystal sizes (Cody 1988). It is likely that a combination of these processes was needed in order to form the gypsum crystals mentioned because gypsum crystals formed from low Ca/SO4 ratios or from microbial activity alone would not result in gypsum crystals large enough, and because gypsum size increases toward the center of the playa where NaCl concentrations are greatest.
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