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Landform

Tectonic Control Of Landforms

In addition to producing its own distinctive land-forms, deformation of Earth's crust is influential in controlling what landforms result from differential weathering and erosion. During major mountain building episodes huge volumes of rock are compressed, folded into complex three-dimensional forms, and sometimes metamorphosed into different kinds of rocks. Later, when these folded layers are exposed to the agents of weathering and erosion, the more resistant units become ridges which outline the folds and deformation. Often resistant units offer better protection at the bottom of the fold than they do at the top, resulting in landforms with higher elevations over what were the troughs in the folds, and lower elevations over what were the crests. Much of the valley and ridge areas of Pennsylvania and adjacent states have this kind of landform.

Resources

Books

Chorley, Richard J., Antony J. Dunn, and Robert P. Beckinsale. The History Of The Study Of Landforms; or, The Development Of Geomorphology. London: Methuen; New York: Wiley, 1964-91.

Cooke, Ron, Andrew Warren, and Andrew Goudie. Desert Geomorphology. London: UCL Press, 1993.

Ollier, Cliff. Ancient Landforms. New York: Belhaven Press, 1991.

Press, Frank, and Raymond Siever. Understanding Earth. New York: W.H. Freeman and Co., 1994.

Periodicals

Wieczorek, Gerald F., et al. "Unusual July 10, 1996, Rock Fall at Happy Isles, Yosemite National Park, California." Bulletin of the Geological Society of America 112, no. 1 (January 2000): 75-85.

Otto H. Muller

KEY TERMS

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Deposition

—Accumulation of sediments at the end of their transport by erosion.

Erosion

—Movement of material caused by the flow of ice, water, or air, and the modification of the surface of the earth (by forming or deepening valleys, for example) produced by such transport.

Fault

—A fracture in the earth's crust accompanied by a displacement of one side relative to the other.

Joint

—A fracture in bedrock across which there has not been significant displacement, but that forms as a result of extensional stresses.

Weathering

—Biological, chemical, and mechanical attack on rock which breaks it up and alters it at or near the surface of Earth.

Additional topics

Science EncyclopediaScience & Philosophy: Kabbalah Mysticism - Types Of Kabbalah to LarynxLandform - Rivers, Glaciers, Wind, Chemical Dissolution And Precipitation, Differential Weathering And Erosion, Volcanism - Erosion and deposition, Tectonic landforms, Joint sets