The white rock formations are called Tufa Towers like in the Mono Lake are calcium carbonate spires and knobs formed by interaction of freshwater springs and alkaline lake water. Tufa can reach heights of 30 ft. (9.1m). Mono Lake is located is Eastern Sierra and covers about 65 square miles. Throughout the lake's existence of over 1 million years, the steady evaporation of freshwater originally coming from Eastern Sierra streams has left the salts and minerals behind so that the lake is now about 2 1/2 times as salty and 80 times as alkaline as the ocean. Mono Lake Tufa is now California state reserve.