What in the world is this very weird stuff that looks as though it has bubbled up out of the lake? I learned something on this trip: It is called tufa (too'-fah). Tufa is essentially common limestone that forms in a very uncommon way. Underwater springs rich in calcium mix with lake water rich in carbonates. As the calcium comes in contact with carbonates in the lake, a chemical reaction occurs resulting in calcium carbonate--limestone. The calcium carbonate forms as a solid around the spring, and over the course of decades to centuries, a tower will grow.
Tufa towers grow exclusively underwater, and some grow to heights of over 30 feet. The reason so much tufa can be seen around Mono Lake today is because the lake level fell dramatically after water diversions began in 1941.