LITTLE SAHARA GUIDE
A lake bed that learned to walk
A river delta, a vanished inland sea, and the one mountain that stopped the wind long enough to drop 124 square miles of sand.
- Lake Bonneville
- The wind did the rest
- Sand Mountain built the dune field
- Still moving
- What that means for riders
Lake Bonneville
Around 15,000 years ago the Sevier River deposited sediment into Lake Bonneville, the enormous prehistoric lake that covered much of western Utah. When the lake receded it left vast deposits of sand exposed across the Sevier Desert.
The wind did the rest
Strong southwesterly winds picked up that exposed sand and carried it northeast. The sand has been transported over 150 miles from its original delta since Lake Bonneville dried.
Sand Mountain built the dune field
Sand Mountain sits in the middle of the field and is the reason the field exists. The mountain deflected the wind upward, causing it to slow and drop its load. Quartz sand fell out among the sagebrush and juniper around it, accumulating into the 124-square-mile dune system that is here now.
Still moving
These are free-moving dunes, not a fossil landscape. They shift an average of five to nine feet every year. The ridge you rode last season is measurably not where it was.
What that means for riders
A dune field that migrates is a dune field whose hazards migrate. Drop-offs, bowls, and slip faces are not fixed features to memorize. This is the geological reason BLM's safety guidance keeps returning to the same instruction: scout the backside before you crest.
BLM Little Sahara Recreation Area · Utah Division of Outdoor Recreation
435-433-5960 · BLM Fillmore Field Office