Maj. John Wesley Powell called parts of it "the Great Unknown." In 1869 the soldier-turned-geologist first led an expedition into this unmapped, 130,000-square-mile region now shared by Colorado, Utah, New Mexico, and Arizona. He found a land of high, desert-like plateaus that in places rose nearly two miles above sea level. Streams and rivers scored the land, slashing awesome canyons and scooping out amphitheaters filled with fantastic rock formations.
