An astronaut onboard the International Space Station (ISS) took this photograph of the Colorado River in southeastern Utah. The river drains a sizable portion of the Rocky Mountain Range and provides water resources to more than 40 million people across seven U.S. states and northern Mexico.
The Glen Canyon National Recreation Area in both Utah and Arizona is characterized by high desert with white to reddish-brown sandstone cliffs of interbedded limestone, which is common in the southwestern United States. About five million years ago, the river began carving into these sedimentary rocks, exposing bedrock that dates back approximately 300 million years. This carving, or fluvial erosion, occurred simultaneously with tectonic uplift (the rising of the landmass).
The Colorado River now lies in its meandering canyon, which includes a dry, relict oxbow. Uplift has raised parts of Glen Canyon National Recreation Area as high as 10,000 feet (3,000 meters) above sea level. The interbedded limestone includes marine fossils from a variety of shallow aquatic environments of the past, such as lagoons and deltas.
Image Credit: ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center