As part of the 50th anniversary of the National Natural Landmarks Program this month, Secretary of the Interior Ken Salazar has designated Lake Shasta Caverns, a pristine cave in northern California, and Ice Mountain, an unusual geological phenomenon called glacière talus in West Virginia, as national natural landmarks.

“With the addition of these two outstanding sites, we now have 593 national natural landmarks, representing the extraordinary geological and ecological diversity of our nation,” Secretary Salazar said in a press release. “These designations provide a means to work in voluntary partnership with public and private landowners to research, monitor and preserve our natural treasures for generations to come.”

Lake Shasta Caverns, a privately-owned solution cave located in Lakehead, California, contains an especially diverse assemblage of calcite cave formations ranging from millimeters to tens of meters. The formations include all the common and many of the more scarce types of cave formations found in solution caves worldwide. The site is open to the public for educational tours.

Ice Mountain in the central Appalachians of eastern West Virginia gets its name from the refrigeration effect that takes place inside its talus — a sloping mass of boulders at the foot of a mountain. In cooler months, dense, cold air sinks deep into the talus, and ice masses form. As the weather warms, the cooler air flows out of vents among the rocks at the bottom of the slope. As a result, the site supports many species normally found in much colder regions.

The mountain also features an outstanding example of Devonian Oriskany sandstone cliffs that enhance the scenic beauty of the area. The site is owned by The Nature Conservancy and provides guided hiking opportunities for the public.

National Natural Landmarks are selected for their outstanding condition, illustrative value, rarity, diversity, and value to science and education. Each site is identified and evaluated through a rigorous process – including a scientific evaluation and public comment period – to formally acknowledge its outstanding biological or geological features.

“This program not only encourages preservation of our nation’s natural heritage, it works to expand our scientific understanding of these unique places,” said National Park Service Director Jonathan B. Jarvis. “Some of the landmarks are the best remaining examples of a type of feature in our nation – sometimes in the world – and we should continue to recognize and support conservation of these important natural features.”

Former Interior Secretary Stewart Udall – who left a great legacy as a guardian of America’s natural landscapes – established the National Natural Landmarks Program in 1962.

The National Natural Landmarks Program is administered by the National Park Service. It is the only natural areas program of national scope to encourage the preservation of the best remaining examples of the nation’s biological and geological features in both public and private ownership. The federal designation imposes no new land use restrictions that were not in effect prior to designation.