Mono Lake Volcanic Field

Geology and History

Aerial view from above Mono Lake towards the west-southwest.

The declining water level of the lake is clearly seen by the parallel lines and white-colored lake deposits ringing the shore. The diversion of fresh-water inflow to the city of Los Angeles and evaporation has led to the decline in water level at a rate of about 1 m per year. The snow-covered mountains in the background are the Sierra Nevada. (Credit: Miller, C. D.. Public domain.)

Mono Lake is the saline remnant of a much larger lake that filled the Mono basin during the Pleistocene. The ancient fresh-water lake, Lake Russell, was named for Israel C. Russel, who first mapped the area in 1881. At its highest level, the shore of Lake Russell once lapped against the foot of the Sierra Nevada about 130 m above its current water level.

Several lava domes and flows in the middle of Mono lake were erupted less than about 1,000 years ago. Paoha Island is predominantly a domed mass of lake-bottom sediments that was uplifted by an intrusion of magma beneath the lake as recently as 350 years ago. The lake is 40-50 m deep immediately west of Paoha Island, and several submarine craters have been identified around the island.