Tufa tower on Mono Lake, California. The lake is a large, shallow lake that formed at least 760,000 years ago as a terminal lake in the basin east of the Sierra-Nevada Range near Lee Vining. Because the lake has no outlet, high levels of salts accumulate making the lake water alkaline.
The Tufa (pronounced "toofah") towers are made from calcium carbonate which makes its way into the lake from underground springs. The calcium and carbonate combine to form limestone which builds up over time around the lake bottom spring openings. Declining lake levels have exposed the tufa towers with some towers up to 30 feet high.
