ISS017-E-006110 (2 May 2008) --- Vermilion Cliffs and Paria River, Arizona are featured in this image photographed by an Expedition 17 crewmember on the International Space Station. The largest tributary of the Colorado River between Lake Powell and the Grand Canyon, the Paria River flows southeast from headwaters in southernmost Utah to join the Colorado River between Page, AZ and Marble Canyon. The Paria River provides spectacular scenery, and is known for the very narrow "slot" canyons that it cuts through the layered rocks of the Colorado Plateau. According to scientists, these canyons formed over millions of years by water erosion slicing deep into the rock layers. Exploring the river channel through the slot canyons is a popular activity for hikers and backpackers. Indeed, there is no road access to much of the river channel, and hiking in on foot is the only way to experience the slot canyons. The Paria River also exposes the red and white layers of rocks beneath the Paria Plateau that are known as the Vermilion Cliffs (center). Scientists say that these rocks record the changing environmental conditions of the region during the early Mesozoic Era, ranging from widespread deserts to more water-rich periods when rivers flowed across the landscape. The spectacular scenery of the Vermilion Cliffs and Paria Canyon falls within the Vermilion Cliffs National Monument. This rugged and remote landscape is also home to many species of raptors -- including the California condor -- and other desert fauna such as bighorn sheep.