Mono Lake is unique. For starters, it's old--at least 700,000 years old and one of the oldest continuously existing lakes on the continent. Fed by huge glaciers during the last Ice Age, Mono Lake was 60 times larger than the 66 square miles it covers today. Mono Lake is naturally salty and alkaline because it has no outlet. The only way water leaves is via evaporation. The Sierra streams that flow into Mono contain only trace amounts of minerals and salts but those minerals and salts stay and their concentrations, over the years, grow.The Eastern Sierra region of California is at once little known and widely loved. Geographically separated from populated California, two main influences create a distinctly wild and scenic character. Attractions along 395 include Bodie, Mono Lake, Devils Postpile National Monument, Mammoth Lakes, Bristlecone Forest and Eureka Sand Dunes, and Mt Whitney .