Earth Observations taken by the Expedition 17 Crew

ISS017-E-005351 (26 April 2008) --- Zion National Park, Utah is featured in this image photographed by an Expedition 17 crewmember on the International Space Station. Zion National Park is located in southwestern Utah, along the western margin of the Colorado Plateau. The park was established in 1919, after roadway improvements in southwestern Utah allowed access to the preceding Mukuntuweap National Monument (1909) located in Zion Canyon. The towering cliffs bounding the North Fork of the Virgin River are formed mainly of tan to light pink Navajo Sandstone, the lithified remnants of an extensive sand dune sea that covered the area during the early Mesozoic Era, nearly 200 million years ago, according to scientists. The Zion region would have looked much like the present-day Sahara desert at this time in its geologic history. Brown rock capping the Navajo Sandstone (right) is comprised of younger beds that record changing environmental conditions that fluctuated between shallow seas and deserts. This high resolution image illustrates the incised nature of the bedrock forming the park. The long linear features are joints -- fractures in the rock mass -- formed in response to tectonic stresses that affected the region during its geologic history. The mainly north-northwest trending joints serve to channelize water runoff and are thought to be the main factor that determined the present canyon network. While the park is perhaps best experienced by hiking, backpacking, or biking, Utah State Route 9 provides automobile access up the side of Zion Canyon. The road is visible in this view as a thin brown line climbing the south wall of the canyon (lower left). Access to the rest of the park is provided by a shuttle bus system instituted in 2000 to reduce vehicle noise, improve air quality, and improve wildlife habitat.