Lake Lewis
Lake Lewis was a large transient lake (lasting only days to weeks) in the Pacific Northwest region of North America, formed by periodic Missoula Floods along the Columbia River paleocourse between 21,000 and 16,000 years ago.
| Lake Lewis | |
|---|---|
This figure shows four profiles of Lake Lewis at various flood levels. It illustrates that the lake back flooded several valleys in which the Touchet Beds were found. | |
Lake Lewis Lake Lewis | |
| Location | North America |
| Coordinates | 46°10′N 119°00′W |
| Lake type | former lake |
| Primary inflows | Channeled Scablands |
| Primary outflows | Wallula Gap of the Columbia River |
| Basin countries | United States |
| Max. length | 105 mi (169 km) |
| Max. width | 130 mi (210 km) |
| Max. depth | 320 ft (98 m) |
| Residence time | 20 incidents |
| Surface elevation | 1,200 ft (366 m) |
| References | Carson, Robert J.; Pogue, Kevin R. (1996). Flood Basalts and Glacier Floods:Roadside Geology of Parts of Walla Walla, Franklin, and Columbia Counties, Washington. Washington State Department of Natural Resources (Washington Division of Geology and Earth Resources Information Circular 90). ISBN none. |
Lake Lewis was formed when the restricted flow of waters from periodic cataclysmic floods from Glacial Lake Missoula, pluvial Lake Bonneville, and perhaps from subglacial outbursts, backed up through the constriction formed by the Wallula Gap in the Horse Heaven Hills (southern Washington). Water also backed up further downstream on the Columbia River between Washington and Oregon, delaying the drainage of Lake Lewis. The water remained for a period of weeks before the flood waters drained through Wallula Gap, just southeast of the Tri-Cities area. Lake Lewis reached an elevation of about 1,200 feet (370 m) above sea level (today's sea level) before subsiding.
Lake Lewis also flooded the Yakima, Walla Walla, Touchet and Tucannon river valleys.