Lake Bonneville

Lake Bonneville is the name of a former lake in the west of present-day United States. He existed in a pluvial in the late Pleistocene, during the last ice age, covering large parts of present-day Utah with foothills north to Idaho and west to Nevada. From him the Great Salt Lake has emerged, as well as most of the smaller lakes in Utah. He was named by Grove Karl Gilbert after Benjamin Bonneville, an officer and fur traders, the parts of the western Rocky Mountains, the Great Basin and Oregon has explored.

16,000 years ago the lake had its largest expansion of approximately 52,000 square kilometers, reaching the magnitude of the current Lake Michigan. Its maximum depth was approximately 300 m. Years ago, some 14,000 broke into the Bonneville flood the lake shore in the north and in a catastrophic flood event he gushed into the plane of the Snake River and laid there and in places on the Columbia Plateau releases the Columbia Plateau basalt, which to this day the landscape in the Snake Columbia River system impressed.

The Lake Bonneville had in the course of its existence fluctuating water levels and shore lines that show up in the form of Tuffablagerungen and terraced bank structures at various locations in Utah. The oldest shoreline is the Stansbury level, which occupies a water level of 1351-1369 m above the sea about 22,000 years ago. This was followed by the Bonneville level around 16,000 years ago with the peak at 1600 m and the Provo level after the flood 14,500 years ago from 1480 to 1490 m. About 11,500 years ago, the lake reached its lowest point and then rose again to the Gilbert level 10,000 years ago, from 1293 to 1305 m. The current water level of the Great Salt Lake lies at 1283 m. Traces of various shorelines are best on Antelope Iceland, an island in the Great Salt Lake to see.

Cause of the fluctuations were and are, as with all effects of Pluvials changes in climate, both the temperature and thus the evaporation, as the rainfall. The minerals, in particular the salts of the sea water, fell out during evaporation and focused on the and gradually exposed bottom. They formed the Great Salt Lake Desert to the west and southwest of the Great Salt Lake with an area of ​​around 10,360 km ², which is famous for its perfectly smooth surface, so -called on the Bonneville Flats race track speed records will be set.

The flood of around 14,000 years ago has also left its mark on the landscape: in the environment of the Red Rock Pass in southern Idaho, south of Downey, the site of the collapse of the lake shore can be found. Here the shore line was formed by sandy alluvial geological past marine structures, which fell under the water pressure. In her break the bedrock was exposed, which consists of Cretaceous dolomite, limestone, and a light brown slate. From here to the Pocatello valley is filled to about 75 km by gravel and pebbles from the flood event. Individual blocks were transported much further.

Trivia

  • In the Wasatch Mountains east of Logan stands on the hillside above the United States Highway U.S. 89 is a stone pillar that marks the level of the water table at the maximum extent of the lake about 16,000 years ago.
  • After the lake in the crater Bonneville was named on Mars.
  • The Triumph Bonneville motorcycle got its name because Triumph and other motorcycle manufacturers lined up multiple speed records on the dry salt lake.
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