Landform

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In the earth sciences and geology sub-fields a landform or physical feature comprises a geomorphological unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography. Landform elements also include seascape and oceanic waterbody interface features such as bays, peninsulas, seas and so forth, including sub-surface terrain features such as submersed mountain ranges, volcanoes, and the great ocean basins under the thin skin of water, for the whole earth is the province and domain of geology.

This panorama in Great Smoky Mountains National Park has the readily identifiable physical features of a rolling plain, actually part of a broad valley, distant foothills, and a backdrop of the old much weathered Appalachian mountain range.
This panorama in Great Smoky Mountains National Park has the readily identifiable physical features of a rolling plain, actually part of a broad valley, distant foothills, and a backdrop of the old much weathered Appalachian mountain range.


[edit] Physical characteristics

Landforms are categorised by characteristic physical attributes such as elevation, slope, orientation, stratification, rock exposure, and soil type.

Gross physical features or landforms include intuitive elements such as berms, mounds, hills, ridges, cliffs, valleys, rivers, peninsulas and numerous other structural and size-scaled (i.e. Ponds vs. Lakes, hills vs. mountains) elements including various kinds of inland and oceanic waterbodies and sub-surface features.

[edit] Heirarchy of classes

Oceans and continents exemplify the highest-order landforms. Landform elements are parts of a high-order landforms that can be further identified and systematically given a cohesive definition such as hill-tops, shoulders, saddles, foreslopes and backslopes.

Some generic landform elements are: pits, peaks, channels, ridges, passes, pools, plains; these can be often extracted from a digital elevation model using some automated techniques[1] where the data (various kinds) has been gathered by modern satellites and stereoscopic aerial surveillance cameras. Until recently, compiling the data found in such data sets required time consuming and expensive techniques of "Boots on the ground" at many man-hours. Terrain (or relief) is the third or vertical dimension of land surface. When relief is described underwater, the term bathymetry is used. Topography is a further synonym, and is often illustrated in the form of a contour map.

Elementary landforms (segments, facets, relief units) are the smallest homogeneous divisions of the land surface, at the given scale/resolution. These are areas with relatively homogenous morphometric properties, bounded by lines of discontinuity. A plateau or a hill can be observed at various scales ranging from few hundred meters to hundreds of kilometers. Hence, the spatial distribution of landforms is often scale-dependent as is the case for soils and geological strata.

A number of factors, ranging from plate tectonics to erosion and deposition, can generate and affect landforms. Biological factors can also influence landforms— for example, note the role of vegetation in the development of dune systems and salt marshes, and the work of corals and algae in the formation of coral reefs.

Landforms do not include man-made features, such as canals, ports and many harbors; and geographic features, such as deserts, forests, grasslands, and impact craters.

Many of the terms are not restricted to refer to features of the planet Earth, and can be used to describe surface features of other planets and similar objects in the Universe.

[edit] List of landforms

Landform element redirects here.

[edit] Coastal and oceanic landforms

Coastal and oceanic landforms.
Coastal and oceanic landforms.

[edit] Erosion landforms

Landforms produced by erosion and weathering usually occur in coastal or fluvial environments, and many appear under those headings. Some other erosion landforms that do not fall into those categories include:

[edit] Fluvial landforms

[edit] Mountain and glacial landforms

[edit] Slope landforms

[edit] Volcanic landforms

[edit] Deposition landform

Landforms produced by deposition of load or sediment (usually coastal or fluvial).

[edit] See also

[edit] References

  1. ^ Robert A. MacMillan, David H. McNabb, R. Keith Jones (September, 2000). Conference paper: "Automated landform classification using DEMs". Retrieved on 2008-06-26.

[edit] External links

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