Mono Lake is located in the vicinity of U.S. Highway 395 and Lee Vining area in the Eastern Sierras. The lake is more than 750,000 years old. It's 2.5 times saltier than ocean water and 80 times more alkaline! Unusual limestone (calcium carbonate) formations are found in the lake. They are called tufas. Also, sand tufas exist there -- smaller, cemented pillars of sand. Wind erosion causes fluting of the pillars. Earthquake activity was involved in protruding the tufa formations to the surface of the lake water. October 2007.