Tufa is a build up of calcium that forms around underwater springs over long periods of time. They are now exposed because the water level at Mono Lake is low. What you are seeing is actually exposed lakebed that was underwater 100 years ago.
How did it get so low? Because Los Angeles pumps its water from the streams that feed this lake. Then they send the water through an aquaduct for hundreds of miles until it gets to LA. They can steal all of this water because long ago they bought all the land from under the ranchers here for its water rights. Seems wrong to me that a city can buy up all this land so far away from its city boundaries and that they can essentially put the area into a never-ending drought.
This is an HDR composed of 5 exposures taken 1 stop apart.