Mono Lake is an alkaline water body due to evaporation in a desert. At South Tufa Reserve area are tufa deposits made of calcium carbonate, left by precipitation around mineral-rich springs within the lake.

Tufa (calcium carbonate) towers along walkway to Mono Lake.	Surface of a tufa formation. Holes broken by earlier visitors reveal that material is fragile and less than 1/4 inch thick.
Tufa deposit in Mono Lake, forming where spring laden with mineral-rich water precipitates calcium carbonate.	Tufa towers within Mono Lake. All the towers were formed below the water surface, but have been revealed by lowered lake level.
Tufa towers within Mono Lake. All the towers were formed below the water surface, but have been revealed by lowered lake level.	Group of university students on statewide natural history tour, learning at Mono Lake from National Forest Service guide. East edge of Sierra Nevada in background.
Pupa of alkali fly, Ephydra hians, that was food staple of Kucadikadi Paiute people indigenous to the area.	Sign marking 6392 feet elevation, marking the 1963 shoreline of Mono Lake, and the lake level mandated by a 1994 court order that has reduced Los Angeles' water withdrawals from the area that began in 1941. Paoha Island, made of lake-bottom sediments pushed up by magma 325 years ago, in background.