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. |
Trapped between the nearly vertical walls of the gorge, the Virgin River flows through the Narrows that it has, over time, gouged from rock. Flash floods hasten the widening and deepening of the canyon. The cement that holds together the rounded grains of quartz in these rocks is readily dissolved by rain that wets the walls and by water that seeps through the rock, loosening tiny particles and permitting them to fall or be swept from the cliff face by showers and wind. Sandstone is reduced to sand, and then is easily removed by streams. 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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