Mono Lake Volcanic Field

Paoha and Negit Islands, Mono Lake, California

Pahoa Island in Mono Lake, California....

This aerial view toward the south shows the northeastern side of Paoha Island; the Mono Craters and Sierra Nevada are in the far distance. The north (bottom of photo) and east (left side of island) tips of the island consist of craters and lava flows that may have erupted as recently as A.D. 1720-1850.

(Credit: Bailey, R. A.. Public domain.)

The islands of Mono Lake were built by recent eruptions of lava and cinder and by uplift of the shallow lake bottom caused by the rise of magma beneath the lake. The two islands are less than about 2,000 years old, and the lava flows on the north flank of Paoha Island are only about 250 years old.

Negit Island in Mono Lake, California....

This high aerial view of Negit Island is toward the southwest. Three separate vents each erupted individual dacite lava flows to form three parallel elongate flows. The vents are located on the highest parts of the flows. The northwest edge of Paoha Island is visible in upper left.

(Credit: Bailey, R. A.. Public domain.)

Most of Paoha Island consists of layers of lake sediments that were pushed up above the water level by rising magma. The north and east tips of the island consist of craters and lava flows that may have erupted as recently as A.D. 1720-1850.

Negit Island in Mono Lake, California....

The three parallel dacite lava flows that form the island are clearly visible.

(Credit: Bailey, R. A.. Public domain.)

The lava flows of Negit Island erupted between about 2,000 and 200 years ago. Three separate vents each erupted individual dacite lava flows to form three parallel elongate flows.