external dynamics of the earth

8/12/2019 External Dynamics of the Earth

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External dynamics of the earth.

Geomorphology: Is the scientific study of landforms and the processes that shape them.

Geomorphologists seek to understand why landscapes look the way they do, to

understand landform history and dynamics and to predict changes through a

combination of field observations.

Weathering: Is the process which causes rocks and minerals to break down anddisintegrate into smaller pieces. It is mainly due to the action of atmospheric agents,

such as water, wind, ice, and ocean movements. Example: mechanical weathering,

chemical weathering and biological weathering.

Chemical weathering: Is the decomposition of rocks through chemical reactions. This

process changes the mineral composition of rocks. It is mainly caused by water.

Mechanical weathering: Is the breakdown of rocks and mineral into smallsi!ed

particles through physical forces. "echanical weathering is mainly caused by changes

in temperature, such as free!ing and thawing, and the effects of wind, rain and waves.

Biological weathering: Is the breakdown of rocks through the activity of living things,

for example, plants.

Freeze-thaw weathering: Its mechanical weathering found in mountains regions. The

main cause is a temperature fluctuation from below free!ing point to above it .

External geomorphological agent: Is a geomorphological agent which is uses to

disintegrate rocks into small pieces. Example: water, ice, wind.

External geomorphological process: Is a process in which living beings, chemical

reactions and physical forces disintegrate rocks and minerals into small pieces. #orexample: chemical weathering, mechanical weathering and biological weathering.

Erosion: Is a process which moves small pieces of weathered rocks to another place.

#or millions of years this process has shaped the landscape.

Transportation: Is a process which moves eroded rock material. It is usually carried

out by the same agent that causes the erosion.

Deposition: Is a process in which rock materials are deposited. It occurs when there is a

decrease in energy in the transporting process. #or example: in the formations of dunes

deposition takes place.


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Win:It$s an atmospheric agent .%ind are movements of large masses of air which are

produced by differences in atmospheric pressures. They can travel hundreds or

thousands of kilometres

!tmosphere: Is a gaseous mass that surrounda planet or star.

Water: It&s a transparent li'uid found in rivers, lakes, seas and in the rain.

"ce: #ro!en water. %hen the water free!e, forms the ice. Ice can crack rocks.

#i$er: #reshwater course which flows down from the mountain to the sea, ocean or

lake.

#ain%all: Is the amount of water falling in rain, snow, etc.

&ea: The expanse of salt water that covers most of the earth$s surface and surrounds itsland masses.

Gro'nwater: (nderground water in the soil or in pores and crevices in rock. It can

forms caves, sinkholes...

D'ne: Is the accumulation of sand. )unes are formed in deserts.

Barchan: Is a crescentshaped sand dune.

#eg: *tones fields produced by deflation.

Erg: +reas of sandy desert.

M'shroom shape roc(: ock whose shape resembles a mushroom formed in deserts

by the eolic abrasion in the bottom because of the sand the wind carries.

De%lation: Is a process in which wind picks up small particles and leaves larger ones.

!)rasion: Is a process in which rock particles -sand are carried by the wind and erode

solid rock.

Glaciers: +re masses of moving ice. They are found in alpine and /olar egions. Ice

moves very slowly from high areas to low areas by the force of gravity. +s a glacier

moves, it drags rock materials and erodes the surfaces in its path. Glaciers cut (shaped

valleys which are called glacial valleys.

Glacial $alley: Glaciers cut (shaped valleys which are called glacial valleys.

Glacial tong'es: +rea which ice form. Glacial tongues carry and deposits rock material

known as moraine.

Moraine: Is a large deposition of rock carried by ice formations called glacial tongues.


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Glacial cir*'e: +re rounded depressions where snow accumulates and changes to ice.

Meaner: +re deep bends in a river that forms when the rivers has less capacity of

erosion. "eanders forms in the middle course of the river.

Delta: + triangular tract of sediment deposited at the mouth of a river, typically whereit diverges into several outlets.

Fairy chimney: + soft rock topped by harderless easily eroded stone that protects the

column from the rainwater. %e can find it in badlands.

G'lly: Is a landform created by running water, eroding sharply into a soft soil, typically

on a hillside.

#a$ine: Is a landform narrower than a canyon and is often the product of streamcutting

erosion avines are typically classified as larger in scale than gullies, although smaller

than valleys.

+arst lanscape:+re landscapes produced by the dissolving action of water on rock,

on or under the surface of the Earth.

Doline:+re depressions which are produced by the collapse of underground cavities.

Ca$e: +re large underground cavities where stalactites and stalagmites form.

&talactite: +re calcium carbonate deposits in caves which grow downward from the

cave floor.

&talagmite: +re calcium carbonate deposits in caves which grow upward from the cave

ceiling.

Car)onation: 0hemical weathering in limestone.

Wa$es: +re effective agent of erosion, transportation and deposition of rock particles

and sand. %ave action shapes sea cliffs which form different coastal landforms.

Ties: +re effective agents of transportation. )uring high tide, waves pick up and carry

sand and other materials from beaches. The waves deposit this material when the tide islower.

C'rrents: +re effective agents of transportation.

Beach: Is a landform along the shoreline of an ocean, sea, lake, or river. It usually

consists of loose particles, which are often composed of rock, such as sand.

Cli%%: Is a vertical, or near vertical, rock exposure. 0liffs are formed due to the

processes of erosion and weathering.

&an )ar: Is a characteristically linear landform completely within or extending into abody of water. It is typically composed of sand and small rocks.


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&eimentation: "oving rock materials are deposited. This process occurs when there is

a decrease in the energy of the transporting agent.

Compaction: Is the formation of sedimentary rocks, the process by which the weight of

sediments on top compresses sediments at the bottom. %ater is s'uee!ed out frombetween the pieces of rock.

+ashi% !hme !hme ,B

external dynamics of the earth

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