Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, John Lockridge, Longmont, Colorado. |
This view looks north from Colorado National Monument across the Grand Valley of the Colorado River, to the Roan Cliffs, and the Book Cliffs. The main view is a mature valley cut by the Colorado River. Terrace levels indicate stages at which the river stabilized for a time and widened its flood plain before beginning another cycle of downcutting and erosion. Landslides form in the talus below freshly scarred cliffs, as erosion of soft shale layers in and below undermines the overlying sandstone layers. Weathering and slope processes continuously widen the valley. Where it is not protected by the sandstone caprock, the shale erodes into humpbacked badlands visible in the distance. The tributary valley in the foreground has retained its steep canyon-like walls, indicating that downcutting is still occurring faster than slope processes that widen and soften the canyon features. Image Credit: John Lockridge, Longmont, Colorado. The hydrologic system, which includes all possible paths of motion of Earth's near-surface fluids including air and water, is largely responsible for the variety of landforms found on the continents. Heat from the sun evaporates water from oceans, lakes, and streams. Although most of the water returns directly as precipitation to the oceans, some of the water is recipitated over land as rain or snow. If it is precipitated over land, it then begins its journey back to the sea as "runoff." The relentless action of surface runoff, streams, and rivers, glaciers, and waves sculpts the rock into intriguing and bizarre shapes. This set of slides includes examples of wave erosion, wind and water erosion, valley shapes, and glacial rosion. The views are often dramatic. Many were taken at U.S. National Parks and Monuments. |
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