About 15 miles southwest of Alamogordo on Hwy 70/82, the 146,535 acre White Sands National Monument is the source of rare gypsum sands as well as snow-white dunes that rise up to 60 feet above the Tularosa Valley floor. Water from rain and melting snow convey tons of gypsum from the mountains into Lake Lucero, in the southwestern portion of the monument. Dry winds exaporate the lake and surrounding alkali flats and carry the broken pieces of crystalline gypsum to the northeast, gradually reducing the fragile pieces to sand and piling it into dunes. Much of the wide sea of dunes is bare of vegetation. A visitor center presents the story of the origin and history of White Sands through exhibits and a sound-and-light program. The center is open daily 8-7, Memorial Day-Labor Day; 8-4:30, rest of year. Closed Dec. 25. Summer programs include guided walks. Also there is a great scenic 16 mile round-trip Dunes Drive, and more.