KERALA PSC / PHYSICAL GEOGRAPHY / CLASSIFICATION OF LANDFORMS / MOUNTAINS / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE

 

KERALA PSC / PHYSICAL GEOGRAPHY / CLASSIFICATION OF LANDFORMS / MOUNTAINS / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE

KERALA PSC / PHYSICAL GEOGRAPHY / CLASSIFICATION OF LANDFORMS / MOUNTAINS / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE

MOUNTAINS

·      An uplifted portion of the earth’s surface is called a hill or a mountain

·      The formation of mountain is the result of tectonic forces which produce compression, tension and isostatic uplift.

·      The mountain building process is known as Orogenesis and the study of mountain is called Orology

·      In our country, a mountain is differentiated from a hill, when its summit or top rises to more than 900 meters above the base

·      Those with less than this elevation are called hills

·      On the basis of their origin or mode of formation, the mountains are classified as structural or tectonic, residual or dissected and volcanic.

 

STRUCTURAL MOUNTAINS

·      All great mountain systems of the earth are of this type

·      Such systems are hundreds of kilometers wide and thousands of kilometers long

·      Many of them lie near or parallel to continental coastlines

·      Both the fold and the block mountains are included in this type.

 

FOLD MOUNTAINS

·      The major mountains of the present day including the Alps in Europe, the Rockies of North America, the Andes of South America and the Himalayas of Asia are structural fold mountains.

·      Fold mountains comprise the largest and most complex mountain system.

·      Mountains of the class are thousands of metre high

·      The granitic core of such mountains is surrounded by metamorphic rocks, merging with sedimentary layers along the margins

·      There are may folds in these mountains which break down under great pressure such folds are called nappe.

·      The new young fold mountains are still rising under the influence of the earth’s tectonic force

·      The Aravallis, considered to be one of the oldest mountains on the earth comes under old fold mountains.

 

BLOCK MOUNTAINS

·      These mountains are formed when great blocks of the earth’s crust may be raised or lowered during the late stages of mountain building

·      The land between the two parallel faults, either rises forming block mountains or horsts, or subsides into a depression termed as a rift valley.

·      An old fold mountain may also be left as block mountains due to continuous denudation

·      The Vosges in France, Black forest mountains in Germany and Salt Range in Pakistan are cited as typical examples of block mountains

·      River Rhine in Europe flows through a rift valley

 

VOLCANIC MOUNTAINS

·      As these are formed by the accumulation of volcanic material, they are also known as mountains of accumulation.

·      The matter is thrown out and deposited around the crater to form a mountain. If the lava is thin and basic in its composition, it spreads a long distance forming a flatter cone of gentler slope and of low elevation.

·      If it is thick and of acid composition a small volcanic cone sharply pointing out is the result.

·      Sometimes lava is thrown out along with ash and cinders. Such a volcanic cone is termed as ash and cinder cone.

·      The Vesuvious in Italy, Fujiyama in Japan, the Aconcagua in Chile, Popacate pelt in Mexico etc… are examples of volcanic mountains.

 

RESIDUAL OR DISSECTED MOUNTAINS

·      They owe their present form due to erosion by different agencies.

·      That is why they are also known as relict mountains or mountains of circumdenudation.

·      Hills like the Nilgiris, the Parasnath, the Girnar and Rajmahal in India are examples of this type.

KERALA PSC / PHYSICAL GEOGRAPHY / CLASSIFICATION OF LANDFORMS / MOUNTAINS / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE