SEMINARON

GEOMORPHIC PROCESSES

CONTENTGEOMORPHIC PROCESSINTRODUCTIONEXOGENETIC PROCESSENDOGENETIC PROCESSEXTRA-TERRESTRIAL PROCESSCONCLUSIONREFERENCE

INTRODUCTION The geomorphic process are all those physical and

chemical changes which effect a modification of the earth surficial form.

A geomorphic agent is any natural medium, which is capable of securing and transporting earth material.

The leading natural agencies that play a major role in this cycle of making and breaking are :-

Running water, ground water, waves and currents, wind, glaciers, lakes and swamps, volcano's and earthquake and living organism.

Most of the geomorphological agents are originate with in the earths atmosphere and are directed by the force of gravity and energized by the sun.

DEGRADATION The process of reducing the elevation of a

high land due to the removal of material by the geomorphic agent may be described as degradation.

Degradation of earth surface is chiefly brought by

Weathering Mass wasting Erosion

WEATHERING

PHYSICAL WEATHERING

FROST ACTION

FROST WEDGING It is a common process of physical

weathering in sub polar region where temperature often vary around freezing point of water

Rock break down caused by expansion of ice in cracks or joint

CRYSTAL GROWTH Growth of crystal in rock fracture with the

evaporation of saline ground water causes disintegration

The salt is in solution and precipitate as soil water and ground water evaporate.

It is most effective in dry land landscapes where water tables are near the surface (e.g., saline seeps)

THERMAL EXPANTION &CONTRATION

Repeated daily heating cooling of causes expansion & contraction

Different minerals expand & contract at different rates causing stress along mineral boundaries

Thermal expansion due to the extreme range of temperatures shutter rocks in desert environments

Repeated swelling and shirking of minerals with different expansion rates will also shatter rock

EXFOLIATION Rock breaks off into leaves or sheets along

joints which parallel the ground surface. Expansion makes cracks parallel to surface. Contraction makes crack right angle to

surface. Layers of rock peel off as expansion

alternates with contraction

CHEMICAL WEATHERING Chemical weathering is the process by which

rocks are decomposed or dissolved or loosened by chemical processes to form residual material.

The agents of chemical weathering are; Water,Oxygen,CO2,Living organism, Acid rain.

HYDRATION The process where minerals in the rock

absorb water and expand, creating stress which cause the disintegration of rock.

Eg:CasO4+2H2O CasO42H2O

HYDROLYSIS Hydrolysis is a chemical weathering process

affecting silicate minerals. In such reactions, pure water ionizes slightly

and reacts with silicate minerals.

SOLUTION It is the process by which rock is dissolved in

water. It is strongly influenced by pH and

temperature. When water becomes saturated, chemicals

may precipitate out forming evaporate deposits.

Calcium carbonate(calcite, limestone),sodium chloride(salt), and calcium sulphate(gypsum) are particularly vulnerable to solution weathering.

OXIDATIONIron combines with oxygen in the presence of water to form iron hydroxide. This processes called oxidation

CARBONATION It is the action of CO2 in combination with the

water which give rise to carbonic acid which is tern responsible for dissolving various rock & minerals

E.g. calcium carbonate + water + carbon dioxide

calcium carbonate

MASS - WASTING Mass wasting is the process that involves the

spontaneous downward movement of soil, regolith and rock under influence of gravity

Mass wasting is usually aided by the presence of water but without any dynamic action of it or in other words the amount of water present is not sufficient to act as a transporting medium

The process occur at speeds ranging from those which are so slow that the movement is imperceptible to rapid flow and catastrophic slumping and rock falls

Evidences of the down slope movement of rock and soil is found almost universally

EROSION Erosion is the process associated with the

geomorphological agents like :-wind, river, glaciers etc.

By which rock materials are loosen or dissolved and then transported from one place to other

Erosion consist of process like :- Collecting together of the loose material

produced by weathering Wearing down the surface and curve out

valley features which is commonly known as abrasion & corrosion

AGGRADATION The process of living up of low land due to

the addition or deposition of material by the agents of gradation

During the transportation an agent like wind, water, glacier, ocean, waves

VOLCANISM Volcanism includes the movement of rock or

magma towards the earth surface It beyond the scope of geomorphology to

explain the complex changes with in the earth which indicate volcanism

Molten rock may be extruded through centralized vents called volcanoes

DIASTROPHISM Diastrophic process are usually classified into

two types Organic (mountain-building with

deformation) Epirogenic (regional uplift without important

deformation) Organic movements are more localized than

are epirogenic and usually involve tangential forces with resulting compression or tension of rock strata

IMPACT OF METEORITES Probably the most usually land forms are

those that originate from the impact of meteorites

Such forms are rather rare but approximately fifty well

Substantiated meteorite craters are known to exist

Their uniqueness lies in the fact that they were produced by extra-terrestrial agents, although the earths gravitate alteration was responsible for the in fall of the meteorites

CONCLUTION The geomorphological process, as already

indicated, play significant roles in shaping the surface of the earth

Depending up on their individual nature and mode of operation, the processes classified into two categories

Exogenetic process Endogenetic process Impact of meteorites is considered as a

special category is named as extraterrestrial

REFERENCE WILLIAM D. THORNBURY, (1954), PRINCIPLES

OF GEOMORPHOLOGY, Page No:-34 Dr.A.V.GEORGE, M.N.RAJESH, T.S.SABITHA

(2005),AN INTRODECTION TO PHYSICAL GEOLOGY AND GEOMORPHOLOGY

BERNAND W.PIPKIN AND D.D.TRENT,(2001), GEOLOGY AND THE ENVIORMENT

PARBIN SINGH, ENGINEERING AND GENARAL GEOLOGY

RAUL A DEJU AND Et al,(1972),THE ENVIORMENT AND ITS RESOURCES

CONT…….. S.M.MATHUR,(2008),ELEMENT OF GEOLOGY G.B.MAHAPATRA,(1994),TEXT BOOK OF

PHYSICAL GEOLOGY P.K.MUKERJEE,(1962),A TEXT BOOK OF

GEOLOGY