Winter is a particularly beautiful time at Mono Lake. The crowds are gone, a quiet stillness prevails, and snow crystals sparkle on the tufa towers. Mono Lake is a majestic body of water in California covering about 65 square miles. It is an ancient lake, over 1 million years old -- one of the oldest lakes in North America. Many columns of limestone rise above the surface of Mono Lake. This type of limestone rock is referred to as tufa, which is a term used for limestone that forms in low to moderate temperatures.