A catastrophic flood caused by overflow and rapid lowering of Pleistocene Lake Bonneville at Red Rock Pass near Preston, Idaho, descended Marsh Creek Valley and reached the Snake River Plain at the site of Pocatello. Large tracts in the upper Snake River Plain were inundated, particularly an area near American Falls and a basin that surrounds Rupert. Farther downstream, the Snake River canyon that extends 200 miles West of Twin Falls was flooded to a depth of 300 feet. Spectacular erosion in the form of abandoned channels, spillways, cataracts, and scabland identifies the flood path between American Falls and Twin Falls, and the canyon farther west is strewn with huge boulders some of them more than 10 feet in diameter, which are heaped in enormous bars of boulders and sand that rise nearly 300 feet above the canyon floor.
Gravity, seismic, and geologic studies indicate that at least 9000 ft of aggregate throw along a zone of northwest-trending, high-angle faults has displaced the western Snake River Plain downward relative to highlands on the north. At least 5000 ft of movement occurred between the early and middle Pliocene. Progressively diminishing movement since then amounts to 4000 ft.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.