Vermilion Cliffs Wilderness, Arizona. Two hikers explore the swirling cross-bedded sandstone formations in the Vermilion Cliffs Wilderness in northern Arizona. Vast fields of sand dunes covered this region 190 million years ago and have since consolidated into sandstone and then uplifted as the entire region was subjected to colossal geologic forces beginning about 10 million years ago. Few displays of cross-bedded sandstone on the Colorado Plateau can rival the colorful variations found here at the edge of the Kaibab uplift in northern Arizona. When combined with the Paria Canyons Wilderness in Utah just across the border, this wilderness area contains a maze of narrow canyons, windswept mesas, and countless hoodoos and pinnacles.