Posted Jan 26, 2024, 6:07 AM
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Registered User
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Join Date: Feb 2016
Posts: 699
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Not development related but here is some interesting information from the Utah Geological survey website about the GSL
Why did lake Boneville form?
Earth is currently in an Ice Age. Much of the last 3 million years has had substantially colder temperatures relative to most of geologic time, with episodes of expansive continental and alpine glaciation. These cold episodes of the Ice Age are called “glacials.” Glacials are interrupted by briefer timespans within the Ice Age of more mild temperatures and retreating glaciers called “interglacials,” such as the one beginning more than 14,000 years ago that continues today. During the last glacial episode, the climate was cooler and wetter in Utah and summers were mild. The input of water into the Bonneville basin exceeded the output by evaporation beginning about 30,000 years ago. Twelve thousand years later the lake had risen to the elevation of the Bonneville shoreline, with glacial extent in the Wasatch Range reaching a maximum 3,000 years before.
Prior glacial episodes had caused other large lakes to form in the Bonneville basin—four massive freshwater lakes in the last 780,000 years—but the last glacial episode likely generated the largest lake and the only lake to overtop the basin threshold and drain to the ocean (see “Where did Lake Bonneville go?”). The larger dimensions of Lake Bonneville occurred in the last glacial episode chiefly because of the diversion of the upper Bear River some 55,000 years ago by lava flows west of Soda Springs, Idaho, that substantially increased the amount of water entering the Bonneville basin.
Where did lake Boneville go?
Around 18,000 years ago, Lake Bonneville had risen to the brim of its basin at Red Rock Pass in southeastern Idaho and began spilling out to the Pacific Ocean via the Snake and Columbia Rivers. At Red Rock Pass, the natural dam of alluvial sediments holding back the lake either was quickly downcut by being overtopped by the lake or the dam of sediments catastrophically failed, initiating the colossal Bonneville flood. The floodwater volume has been estimated at around 1,100 cubic miles (more than 1.2 quadrillion gallons), comparable to the volume of water in Lake Michigan. Within weeks to months after the breach, the lake lowered around 425 feet until a new, lower threshold was established. Over the centuries the threshold rose as landslides and gigantic blocks of bedrock at Red Rock Pass relentlessly plunged into the lake’s outlet. The lake drained to the Pacific Ocean for some 1,000 to 3,000 years and created a prominent “Provo” shoreline below the Bonneville shoreline. As the climate warmed the lake contracted and eventually reached the level of modern Great Salt Lake by 13,000 years ago.
There’s plenty of other good information and the frequently ask questions on the Utah Geological Survey website is pretty interesting as well. geology.utah.gov
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