HYDROLOGY OF LAKE BONNEVILLE AND SEDIMENTS AND SOILS OF ITS BASIN

The total salt in the Bonneville basin in the form of salt crusts, salt water in clays, and salt in the Great Salt Lake brine is about 6 billion tons. The annual rate of addition of new salt by the inflowing rivers is about 1 million tons. Thus the time of accumulation since the last overflow should be 6000 years approximately, but C¹⁴ analyses indicate a time in excess of 30,000 years. The writers believe that the wind is responsible for the removal of the salt from the basin floor.

Should Great Salt Lake rise 20–30 feet it would spill at Lakeside into the Great Salt Lake Desert; the lake's surface would suddenly increase two times and produce a stabilized lake level. A major beach about 45 feet above Great Salt Lake is vividly impressed on the topography; it is believed to be related to the Great Salt Lake Desert expansion.

Cores from Great Salt Lake indicate that the last fresh-water lake existed from about 23,000 years to 13,500 years ago. This correlates with C¹⁴ analyses of tufa at the Stansbury level.

Soils of several ages and varieties are recognized and in their relations to the various lake deposits and associated river terraces support the other evidence from which the following chronology of lake stages is postulated:

• Alpine stage (5050 feet ±)—first high-level lake, possibly Kansan

  • Low lake stage—possibly Sangamon-Illionian-Yarmouth

• Bonneville-Provo 1 stage (5135 feet ±)—Tazewell-Iowan, overflow stage

  • Low-lake stage—Brady

• Provo 2 stage (4820 feet ±)—Cary

  • Low lake stage—Two Creeks

• Stansbury stage (4470 feet ±)—about 23,000 to 13,500 years ago. Mankato

• Gilbert stage (4245 feet ±)—about 10,000 to 8000 years ago. May be a minor pluvial maximum or a stability level in the recession of the lake.

  • Altithermal—about 6000 years ago