Close view of tufa deposits along the shore of Mono Lake. The tufa deposits form underwater as calcium-rich groundwater enters the lake from a spring or fracture. The spring water reacts with dissolved carbonates in the lake water to form calcium carbonate, or limestone. The calcium carbonate forms a deposit upward from the lake bottom, and over tens to hundreds of years, can build tufa towers more than 10 m tall. The tufa deposits are visible today because the lake's water level has fallen dramatically since 1941, which is when fresh water flowing into the lake was diverted to the city of Los Angeles.