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Information about Geomorphology

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Surface of the Earth


Geomorphology (from Greek: γη, ge, "earth"; μορφή, morfé, "form"; and λόγος, logos, "knowledge") is the study of landforms, including their origin and evolution, and the processes that shape them. The underlying question is: Why do landscapes look the way they do? Geomorphologists seek to understand landform history and dynamics, and predict future changes through a combination of field observation, physical experiment, and numerical modeling. The discipline is practiced within geology, geodesy, geography, archaeology, and civil and environmental engineering. Early studies in geomorphology are the foundation for pedology, one of two main branches of soil science.

Landforms evolve in response to a combination of natural and anthropogenic processes. The landscape is built up through tectonic uplift and volcanism. Denudation occurs by erosion and mass wasting, which produces sediment that is transported and deposited elsewhere within the landscape or off the coast. Landscapes are also lowered by subsidence, either due to tectonics or physical changes in underlying sedimentary deposits. These processes are each influenced differently by climate, ecology, and human activity.

Practical applications of geomorphology include measuring the effects of climate change, hazard assessments including landslide prediction and mitigation, river control and restoration, coastal protection, and assessing the presence of water on Mars.

Paleogeomorphology is the study of the geomorphology of all or part of the earth's surface at some time in the earth's past.

History

Perhaps the earliest one to devise a theory of geomorphology was the polymath Chinese scientist and statesman Shen Kuo (1031-1095 AD). This was based on his observation of marine fossil shells in a geological stratum of a mountain hundreds of miles from the Pacific Ocean. Noticing bivalve shells running in a horizontal span along the cut section of a cliffside, he theorized that the cliff was once the pre-historic location of a seashore that had shifted hundreds of miles over the centuries. He inferred that the land was reshaped and formed by soil erosion of the mountains and by deposition of silt, after observing strange natural erosions of the Taihang Mountains and the Yandang Mountain near Wenzhou. Furthermore, he promoted the theory of gradual climate change over centuries of time once ancient petrified bamboos were found to be preserved underground in the dry, northern climate zone of Yanzhou, which is now modern day Yan'an, Shaanxi province.

Geomorphology was not originally differentiated from the rest of geography. The first geomorphic model was the geographical cycle or the cycle of erosion, developed by William Morris Davis between 1884 and 1899. The cycle was inspired by theories of uniformitarianism which were first formulated by James Hutton (1726-1797). Concerning valley forms, the cycle was depicted as a sequence by which a river would cut a valley more and more deeply, but then erosion of side valleys would eventually flatten out the terrain again, now at a lower elevation. The cycle could be started over by uplift of the terrain. The model is today considered too much of a simplification to be especially useful in practice.

Walther Penck developed an alternative model in the 1920s, based on ratios of uplift and erosion, but it was also too weak to explain a variety of landforms. G. K. Gilbert was an important early American geomorphologist.

Processes

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Age of seafloor crust. Red is youngest.
Modern geomorphology focuses on the quantitative analysis of interconnected processes, such as the contribution of solar energy, the rates of steps of the hydrologic cycle, plate movement rates from geophysics to compute the age and expected fate of landforms and the weathering and erosion of the land. The use of more precise measurement technique has also enabled processes like erosion to be observed directly, rather than merely surmised from other evidence. Computer simulation is also valuable for testing that a particular model yields results with properties similar to real terrain.

Primary surface processes responsible for most topographic features include wind, waves, weathering, mass wasting, ground water, surface water, glaciers, tectonism, and volcanism.

Fluvial geomorphology

Rivers and streams are not only conduits of water, but also of sediment. The water, as it flows over the channel bed, is able to mobilize sediment and transport it downstream, either as bedload, suspended load or dissolved load. The rate of sediment transport depends on the availability of sediment itself and on the river's discharge.

As rivers flow across the landscape, they generally increase in size, merging with other rivers. The network of rivers thus formed is a drainage system and is often dendritic, but may adopt other patterns depending on the regional topography and underlying geology.

Glacial geomorphology

Glaciers, while geographically restricted, are effective agents of landscape change. The gradual movement of ice down a valley causes abrasion and plucking of the underlying rock. Abrasion produces fine sediment, termed glacial flour. The debris transported by the glacier, when the glacier recedes, is termed a moraine. Glacial erosion is responsible for U-shaped valleys, as opposed to the V-shaped valleys of fluvial origin.
See also: Glacier morphology

Weathering

Main article: Weathering
This results from chemical dissolution of rock and from the mechanical wearing of rock by plant roots, ice expansion, and the abrasive action of sediment. Weathering provides the source of the sediment transported by fluvial, glacial, aeolian, or biotic processes.

Taxonomy

Different geomorphological processes dominate at different spatial and temporal scales. To help categorize landscape scales some geomorphologists use the following taxonomy:

See also

References

  • Selby, M. J. (1985). Earth's Changing Surface. Oxford: Oxford University Press. ISBN 0-19-823252-7. 
  • Chorley, Richard; Stanley Schumm, and David Sugden (1984). Geomorphology. London: Edition Methuen. ISBN 0-416-32590-4.Methuen&rft.place=London&rft.isbn=0-416-32590-4"> 
  • Edmaier, Bernhard (2004). Earthsong. A collection of breathtaking arial photographs. Berlin: Phaidon Press. ISBN 0-7148-9424-9. 
  • Scheidegger, Adrian E. (2004). Morphotectonics. Berlin: Springer-Verlag. ISBN 3-540-20017-7. 
  • Needham, Joseph (1986). Science and Civilization in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth. Taipei: Caves Books Ltd.. 

External links

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Sub-fields of Physical Geography
A landform 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.
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landscape comprises the visible features of an area of land, including physical elements such as landforms, living elements of flora and fauna, abstract elements such as lighting and weather conditions, and human elements, for instance human activity or the built environment.
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mathematical model is an abstract model that uses mathematical language to describe the behaviour of a system. Mathematical models are used particularly in the natural sciences and engineering disciplines (such as physics, biology, and electrical engineering) but also in the social
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Oceanic crust      0-20 Ma
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Geodesy (IPA North American English /dʒiˈɑdɪsi/; British, Australian English etc. /dʒɪˈɒdəsi/), also called geodetics
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Geography - (from the Greek words Geo (γη) or Gaea (γαία), both meaning "Earth", and graphein (γράφειν) meaning "to describe" or "to write"
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This high-risk template has been protected from editing to prevent vandalism.
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Civil engineering is a professional engineering discipline that deals with the design and construction of the physical and natural built environment, including works such as bridges, roads, canals, dams and buildings.
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Environmental engineering[1][2] is the application of science and engineering principles to improve the environment (air, water, and/or land resources), to provide healthy water, air, and land for human habitation and for other organisms, and to remediate
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Pedology (from Greek: γη, pedon, "soil"; and λόγος, logos, "knowledge") is the study of soils in its natural environment.[1] It is one of two main branches of soil science, the other being edaphology.
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Soil science deals with soil as a natural resource on the surface of the earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils per se; and these properties in relation to the use and management of soils.
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Anthropogenic effects, processes, objects, or materials are those that are derived from human activities, as opposed to those occurring in natural environments without human influences.
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Tectonic uplift is a geological process most often caused by plate tectonics which increases elevation. The opposite of uplift is subsidence, which results in a decrease in elevation. Uplift may be orogenic or isostatic.
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Volcano:
1. Large magma chamber
2. Bedrock
3. Conduit (pipe)
4. Base
5. Sill
6. Branch pipe
7. Layers of ash emitted by the volcano
8. Flank 9. Layers of lava emitted by the volcano
10. Throat
11. Parasitic cone
12. Lava flow
13. Vent
14.
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Denudation is the process by which the removal of material, through means of erosion and weathering, leads to a reduction of elevation and relief in landforms and landscapes. Exogenic processes, including the action of water, ice, and wind, predominantly involve denudation.
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Erosion is displacement of solids (soil, mud, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement in response to gravity or by living organisms (in the case of bioerosion).
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Mass wasting, also known as mass movement or slope movement, is the geomorphic process by which soil, regolith, and rock move downslope under the force of gravity.
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Deposition is the geological process whereby material is added to a landform. This is the process by which wind and water create a deposit, through the laying down of granular material that has been eroded and transported from another geographical location.
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Climate is the average and variations of weather over long periods of time. Climate zones can be defined using parameters such as temperature and rainfall.
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Ecology (also known as Oekologie, Okology, or Oekology[1],from Greek: οίκος, oikos, "household"; and λόγος, logos
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landslide is a geological phenomenon which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows. Although gravity's action on an over-steepened slope is the primary reason for a landslide, there are other contributing factors
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river is a natural waterway that transits water through a landscape from higher to lower elevations. It is an integral component of the water cycle. The water within a river is generally collected from precipitation through surface runoff, groundwater recharge (as seen at baseflow
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Mars  

Mars as seen by the Hubble Space Telescope
Orbital characteristics
Epoch J2000<ref name="nssdc" />
Aphelion distance: 249,228,730 km
1.66599116 AU
Perihelion distance: 206,644,545 km
1.
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The history of China is told in traditional historical records that refer as far back as the Three Sovereigns and Five Emperors about 5,000 years ago, supplemented by archaeological records dating to the 16th century BC. China is one of the world's oldest continuous civilizations.
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Shen Kuo (沈括)

Shen Kuo, a Chinese scientist famous for his concepts of true north and land formation, among others.
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10th century - 11st century - 12nd century
1000s  1010s  1020s  - 1030s -  1040s  1050s  1060s
1028 1029 1030 - 1031 - 1032 1033 1034

Lists of leaders
State leaders - Sovereign states

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10th century - 11st century - 12nd century
1060s  1070s  1080s  - 1090s -  1100s  1110s  1120s
1092 1093 1094 - 1095 - 1096 1097 1098

Lists of leaders
State leaders - Sovereign states

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Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine geology. As a noun it can be a term for a certain kind of navy, or those enlisted in such a navy.
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For other uses of the term, see Fossil (disambiguation)


FOSSIL is a standard for allowing serial communication for telecommunications programs under the DOS operating system.
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Oceanic crust      0-20 Ma
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