How Did Sand Mountain Form?
Only 10,000 years ago glaciers filled many of the valleys in the Sierra Nevada mountains to the west. The cool, wet climate and runoff from these glaciers helped to create ancient Lake Lahontan, an immense inland lake that covered much of what is now northern Nevada. Scientists say that the ancient lake was once over 800 feet deep in places. If you visit Sand Mountain today you can spot the ancient lakeshores on the bluffs to the east of the dunes.
As the climate thousand of years ago grew warmer the glaciers retreated and the the lake slowly started to dry up. By 4,000 years ago the lake level dropped below where Sand Mountain now stands.
Quartz particles, which the glaciers had ground away from the hard Sierra granite to the west, eventually washed down the Walker River and deposited in the river's delta. As the wind blew across the delta this sand was picked up and carried high into the air. More than thirty miles to the northeast, the wind was slowed by a large basin on the southwest flank of the Stillwater Range. With its force broken by the mountain, the wind's burden of sand would fall into this natural trap.
Over the centuries Sand Mountain grew until it reached its present height of almost 600 feet.