Mono Lake is a saline soda lake in Mono County, California, formed at least 760,000 years ago as a terminal lake in an endorheic basin. The lack of an outlet causes high levels of salts to accumulate in the lake which makes its water alkaline.

The best-known features of Mono Lake are its dramatic tufa (TOO-fuh) towers. Over time, rainfall at Mono Lake did not keep up with evaporation, and minerals in the water built up. The lake is now 2.5 times as salty and 80 times as alkaline as the ocean.

All tufa at Mono Lake forms underwater. Beneath Mono Lake, calcium-rich freshwater springs seep up from the lake bottom and mix with lake water rich in carbonates (think baking soda). As the calcium comes in contact with the carbonates in the lake, a chemical reaction occurs, resulting in calcium carbonate, or limestone. The calcium carbonate precipitates (settles out of solution as a solid) around the spring, and over the course of decades to centuries, a tufa tower will grow. Tufa towers can grow to heights of over 30 feet underwater.

Tufa towers are not the only form of tufa at Mono Lake. Calcium carbonate crystals will also precipitate out of lake water far from springs and coat lake bottom surfaces like pumice boulders, dead vegetation, and anything else that might end up in the lake.

Mono Lake is an interesting and incredibly important ecosystem. It is home to trillions of tiny, black alkali flies and many brine shrimp. These small food sources feed the millions of migratory birds, such as California gulls, that visit Mono Lake every year.

According to the Internet