Lake Bonneville
Lake Bonneville existed from roughly 32,000 to 15,500 years ago in the late pleisteine period, and took up a large part of Utah and some of Nevada and Idaho. The lake was, at its largest, 135 miles wide, and 325 miles long. The lake also had an impressive maximum depth of over 1,000 feet and covered about 20,000 square miles. Lake Bonneville existed in a wetter and cooler period of time, and was formed by rivers, streams, melt water from glaciers, and precipitation.
About 14,500 years ago, the lake level fell catastrophically as Lake Bonneville discharged an immense volume of water northward. The flood was thought to be caused by the Bear River, which increased the Lake’s water supply, to the point of causing it to overflow into Red Rock Pass, in Idaho. The flood continued west across the Snake River Plain roughly following the path of the present Snake River.
The flood left a record on the earth of its effects in the Snake River Plain by a variety of erosion and depositional features. At Portneuf Narrows, a canyon 45 miles northwest of Red Rock Pass, the flood is estimated to have reached a height of 400 feet. The estimated maximum discharge of the flood was around one-third cubic miles per hour, or 15 million cubic feet per second, and the total volume of the flood water released was around 380 cubic miles. The most catastrophic discharge of the Lake’s water released the vast majority of it’s volume in just a few days, creating many impressive geological features. The flood as a whole, however, lasted for more than a year.
Grove Karl Gilbert conducted the first scientific study of the Lake Bonneville terraces in the 1870’s. Gilbert was a pioneer in the first geological and geographical surveys of the Colorado Plateau and of Utah. His study of Lake Bonneville terraces was released in 1890 as Monograph 1, one of the first publications of the new U. S. Geological Survey.
About 14,500 years ago, the lake level fell catastrophically as Lake Bonneville discharged an immense volume of water northward. The flood was thought to be caused by the Bear River, which increased the Lake’s water supply, to the point of causing it to overflow into Red Rock Pass, in Idaho. The flood continued west across the Snake River Plain roughly following the path of the present Snake River.
The flood left a record on the earth of its effects in the Snake River Plain by a variety of erosion and depositional features. At Portneuf Narrows, a canyon 45 miles northwest of Red Rock Pass, the flood is estimated to have reached a height of 400 feet. The estimated maximum discharge of the flood was around one-third cubic miles per hour, or 15 million cubic feet per second, and the total volume of the flood water released was around 380 cubic miles. The most catastrophic discharge of the Lake’s water released the vast majority of it’s volume in just a few days, creating many impressive geological features. The flood as a whole, however, lasted for more than a year.
Grove Karl Gilbert conducted the first scientific study of the Lake Bonneville terraces in the 1870’s. Gilbert was a pioneer in the first geological and geographical surveys of the Colorado Plateau and of Utah. His study of Lake Bonneville terraces was released in 1890 as Monograph 1, one of the first publications of the new U. S. Geological Survey.