Dirty Devil Canyons, Utah. A deep subterranean chamber glows in midday light along the Dirty Devil River in south-central Utah as a wetsuit-clad canyoneer takes a moment to rest. The Colorado Plateau of southern Utah is composed of multiple layers of horizontally-bedded sedimentary rock including sandstones and limestone. These layers were deposited over the last several hundred million years and only recently have been eroded as this entire region was elevated by large geologic forces beginning about 10 million years ago. As flowing water cut down into these layers, countless narrow canyons have been created throughout the region.