About three million years ago, a volcano dominated the landscape east of U.S. 191. Wind and water eroded the softer rocks around the volcano’s more resistant core, leaving the tooth-shaped butte called Boars Tusk on the eastern horizon. Rising over 400 feet above the desert floor, it stands over the Killpecker Sand Dunes, a narrow belt of wind-blown sand stretching for over 60 miles across the Continental Divide and forming the largest dune field in North America. Sands began accumulating about 15,000 years ago near the end of the Ice Age, and today active dunes in the center of the field reach tens of feet in height, while the margins are stabilized by fragile vegetation and the distant white spots are small patches of active sand. For thousands of years, Native Americans have recognized and revered the sacred power of this landscape, using many places for seclusion and prayer. The White Mountain petroglyphs and similar regional sites attest to this sacred power and to traditions and ceremonies that have continued across the landscape for thousands of years.