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. |
Eroded columns, pinnacles and formations in Bryce Canyon National Park, Utah. The delicate coloring and formations are produced by chemical weathering. This form of weathering occurs wherever seeping ground water circulating through the sandstone dissolves the calcium-carbonate cement between the individual grains, causing the rock to crumble to sand. Cavities work their way back into the walls of the escarpment. Over time, the cavities deepen and roofs collapse. Columns are formed which, in turn, finally topple. Pink, white, yellow, and red formations are produced by oxidation (chemical weathering) of the iron-bearing minerals found in the rock. 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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