Cranesville Swamp Preserve is a 1,600-acre protected wetland on the West Virginia-Maryland border whose natural bowl, or frost pocket, traps cold air and creates an unusually northern habitat in the Appalachians. Nineteen plant communities have been identified there, including sphagnum moss, speckled alder, sedges, grasses, and bog plants such as round-leaved sundew and narrowleaf gentian. It is especially important for containing the southernmost natural community of American larches. Its wildlife also reflects this northern character, with black bear, porcupine, snowshoe hare, rare northern water shrews, and uncommon birds. The Nature Conservancy began acquiring the land in 1960, and it became one of the first National Natural Landmarks in 1964.