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PHYSIOGRAPHY

This unit deals with Structure and Relief; physiographic divisions

Drainage systems: concept of water sheds the Himalayan

and the Peninsular

UNITII

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D

o you know that our earth also has ahistory. The earth and its landformsthat we see today have evolved over a

very long time. Current estimation shows thatthe earth is approximately 460 million years old.Over these long years, it has undergone manychanges brought about primarily by theendogenic and exogenic forces. These forces haveplayed a significant role in giving shape to varioussurface and subsurface features of the earth. Youhave already studied about the Plate Tectonicsand the movement of the Earths plates in thebook Fundamentals of Physical Geography(NCERT, 2006). Do you know that the Indianplate was to the south of the equator millions of

years ago? Do you also know that it was muchlarger in size and the Australian plate was a partof it? Over millions of years, this plate broke intomany parts and the Australian plate movedtowards the southeastern direction and theIndian plate to the north. Can you map differentphases in the movement of the Indian plate? Thisnorthward movement of the Indian plate is stillcontinuing and it has significant consequenceson the physical environment of the Indiansubcontinent. Can you name some importantconsequences of the northward movement of theIndian plate?

It is primarily through the interplay of theseendogenic and exogenic forces and lateralmovements of the plates that the present geologicalstructure and geomorphologic processes activein the Indian subcontinent came into existence.Based on the variations in its geological structureand formations, India can be divided into threegeological divisions. These geological regionsbroadly follow the physical features:

(i) The Penisular Block(ii) The Himalayas and other Peninuslar

Mountains

(iii) Indo-Ganga-Brahmaputra Plain.

THE PENINSULAR BLOCK

The northern boundary of the PeninsularBlock may be taken as an irregular linerunning from Kachchh along the western flankof the Aravali Range near Delhi and thenroughly parallel to the Yamuna and the Gangaas far as the Rajmahal Hills and the Gangadelta. Apart from these, the Karbi Anglong andthe Meghalaya Plateau in the northeast andRajasthan in the west are also extensions of

this block. The northeastern parts areseparated by the Malda fault in West Bengalfrom the Chotanagpur plateau. In Rajasthan,the desert and other desertlike featuresoverlay this block.

The Peninsula is formed essentially by agreat complex of very ancient gneisses andgranites, which constitutes a major part of it.Since the Cambrian period, the Peninsula hasbeen standing like a rigid block with theexception of some of its western coast whichis submerged beneath the sea and some otherparts changed due to tectonic activity without

affecting the original basement. As a part ofthe Indo-Australian Plate, it has been subjectedto various vertical movements and blockfaulting. The rift valleys of the Narmada, theTapi and the Mahanadi and the Satpura blockmountains are some examples of it. ThePeninsula mostly consists of relictand residualmountains like the Aravali hills, the Nallamalahills, the Javadi hills, the Veliconda hills, the

STRUCTUREAND PHYSIOGRAPHY

C H A P T E R

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9STRUCTURE AND PHYSIOGRAPHY

Palkonda range and the Mahendragiri hills, etc.The river valleys here are shallow with lowgradients.

You are aware of the method of calculatingthe gradient as a part of your study of the bookPractical Work in Geography Part I (NCERT,2006). Can you calculate the gradient of theHimalayan and the Peninsular rivers and drawthe comparisons?

Most of the east flowing rivers form deltasbefore entering into the Bay of Bengal. Thedeltas formed by the Mahanadi, the Krishna,the Kaveri and the Godavari are importantexamples.

THE HIMALAYASANDOTHER

PENINSULAR MOUNTAINS

The Himalayas along with other Peninsularmountains are young, weak and flexible in theirgeological structure unlike the rigid and stablePeninsular Block. Consequently, they are stillsubjected to the interplay of exogenic andendogenic forces, resulting in the development offaults, folds and thrust plains. These mountainsare tectonic in origin, dissected by fast-flowingrivers which are in their youthful stage. Variouslandforms like gorges, V-shaped valleys, rapids,waterfalls, etc. are indicative of this stage.

INDO-GANGA-BRAHMAPUTRAPLAIN

The third geol ogical division of Indiacomprises the plains formed by the riverIndus, the Ganga and the Brahmaputra.Originally, it was a geo-synclinal depressionwhich attained its maximum development

during the third phase of the Himalayanmountain formation approximately about 64million years ago. Since then, it has been

gradually filled by the sediments brought bythe Himalayan and Peninsular rivers. Averagedepth of alluvial deposits in these plainsranges from 1,000-2,000 m.

It is evident from the above discussion thatthere are significant variations among thedifferent regions of India in terms of theirgeological structure, which has far-reachingimpact upon other related aspects. Variationsin the physiography and relief are importantamong these. The relief and physiography ofIndia has been greatly influenced by thegeological and geomorphological processes

active in the Indian subcontinent.

PHYSIOGRAPHY

Physiography of an area is the outcome ofstructure, process and the stage ofdevelopment. The land of India is characterisedby great diversity in its physical features. Thenorth has a vast expanse of rugged topographyconsisting of a series of mountain ranges withvaried peaks, beautiful valleys and deep gorges.The south consists of stable table land withhighly dissected plateaus, denuded rocks anddeveloped series of scarps. In between thesetwo lies the vast north Indian plain.

Based on these macro variations, India canbe divided into the following physiographicdivisions:

(1) The Northern and North-easternMountains

(2) The Northern Plain(3) The Peninsular Plateau(4) The Indian Desert(5) The Coastal Plains(6) The Islands.

The North and Northeastern Mountains

The North and Northeastern Mountains consistof the Himalayas and the Northeastern hills.The Himalayas consist of a series of parallelmountain ranges. Some of the importantranges are the Greater Himalayan range,which includes the Great Himalayas and

Figure 2.1 : A Gorge

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10 INDIA : PHYSICAL ENVIRONMENT

Figure 2.2 : India : Physical

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the Trans-Himalayan range, the MiddleHimalayas and the Shiwalik. The generalorientation of these ranges is from northwest to

the southeast direction in the northwestern partof India. Himalayas in the Darjiling and Sikkimregions lie in an eastwest direction, while inArunachal Pradesh they are from southwest tothe northwest direction. In Nagaland, Manipurand Mizoram, they are in the northsouthdirection. The approximate length of the GreatHimalayan range, also known as the centralaxial range, is 2,500 km from east to west, andtheir width varies between 160-400 km fromnorth to south. It is also evident from the mapthat the Himalayas stand almost like a strong

and long wall between the Indian subcontinentand the Central and East Asian countries.

Himalayas are not only the physical barrier,they are also a climatic, drainage and culturaldivide. Can you identify the impact of Himalayason the geoenvironment of the countries of SouthAsia? Can you find some other examples ofsimilar geoenvironmental divide in the world?

There are large-scale regional variationswithin the Himalayas. On the basis of relief,alignment of ranges and other geomorphologicalfeatures, the Himalayas can be divided into thefollowing sub-divisions:

(i) Kashmir or Northwestern Himalayas

(ii) Himachal and Uttaranchal Himalayas(iii) Darjiling and Sikkim Himalayas(iv) Arunachal Himalayas(v) Eastern Hills and Mountains.

Kashmir or Northwestern Himalayas

It comprise a series of ranges such as theKarakoram, Ladakh, Zaskar and Pir Panjal. The

northeastern part of the Kashmir Himalayas is acold desert, which lies between the GreaterHimalayas and the Karakoram ranges. Between

the Great Himalayas and the Pir Panjal range,lies the world famous valley of Kashmir and thefamous Dal Lake. Importantglaciers of South Asia suchas the Baltoro and Siachenare also found in this region.The Kashmir Himalayas arealso famous for Karewaformations, which are usefulfor the cultivation ofZafran,

a local variety of saffron. Some of the importantpasses of the region are Zoji La on the GreatHimalayas, Banihal on the Pir Panjal, Photu La

on the Zaskar and Khardung La on the Ladakhrange. Some of the important fresh lakes suchas Dal and Wular and salt water lakes such asPangong Tso and Tso Moriri are also in thisregion. This region is drained by the river Indus,and its tributaries such as the Jhelum and theChenab. The Kashmir and northwesternHimalayas are well-known for their scenicbeauty and picturesque landscape. Thelandscape of Himalayas is a major source ofattraction for adventure tourists. Do you knowthat some famous places of pilgrimage such asVaishno Devi, Amarnath Cave, Charar -e-Sharif,

etc. are also located here and large number ofpilgrims visit these places every year?

Srinagar, capital city of the state of Jammuand Kashmir is located on the banks of Jhelumriver. Dal Lake in Srinagar presents aninteresting physical feature. Jhelum in the valleyof Kashmir is still in its youth stage and yet formsmeanders a typical feature associated with the

Figure 2.3 : The Himalayas

KarewasKarewas are thethick deposits ofglacial clay andother materialsembedded withmoraines.

Figure 2.4 : Meandering Jhelum

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mature stage in the evolution of fluvial land form(Figure 2.4). Can you name some other fluviallandforms in the mature stage of a river?

The southernmost part of this region consistsof longitudinal valleys known as duns. Jammudun and Pathankot dun are important examples.

The Himachal and Uttarakhand Himalayas

This part lies approximately between the Raviin the west and the Kali (a tributary ofGhaghara) in the east. It is drained by two majorriver systems of India, i.e. the Indus and theGanga. Tributaries of the Indus include the riverRavi, the Beas and the Satluj, and thetributaries of Ganga flowing through this

region include the Yamuna and the Ghaghara.The northernmost part of the HimachalHimalayas is an extension of the Ladakh colddesert, which lies in the Spiti subdivision ofdistrict Lahul and Spiti. All the three ranges ofHimalayas are prominent in this section also.These are the Great Himalayan range, the LesserHimalayas (which is locally known asDhaoladhar in Himachal Pradesh and Nagtibhain Uttarakhand) and the Shiwalik range fromthe North to the South. In this section of LesserHimalayas, the altitude between 1,000-2,000

m specially attracted to the British colonialadministration, and subsequently, some of theimportant hill stations such as Dharamshala,Mussoorie, Shimla, Kaosani and thecantonment towns and health resorts such asShimla, Mussoorie, Kasauli, Almora,Lansdowne and Ranikhet, etc. were developedin this region.

The two distinguishing features of this

An Interesting FactIn Kashmir Valley, the meanders in Jhelumriver are caused by the local base levelprovided by the erstwhile larger lake of whichthe present Dal Lake is a small part.

Figure 2.5 : Western Himalayas

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region from the point of view of physiographyare the Shiwalik and Dun formations. Someimportant duns located in this region are theChandigarh-Kalka dun, Nalagarh dun, Dehra

Dun, Harike dun and the Kota dun, etc. DehraDun is the largest of all the duns with anapproximate length of 35-45 km and a widthof 22-25 km. In the Great Himalayan range,the valleys are mostly inhabited by theBhotias. These are nomadic groups whomigrate to Bugyals (the summer glasslandsin the higher reaches) during summer monthsand return to the valleys during winters. Thefamous Valley of flowers is also situated in thisregion. The places of pilgrimage such as theGangotri, Yamunotri, Kedarnath, Badrinathand Hemkund Sahib are also situated in thispart. The region is also known to have fivefamous Prayags (river confluences) asmentiond in Chapter 3 of this book. Can youname some other famous prayags in otherparts of the country?

The Darjiling and Sikkim Himalayas

They are flanked by Nepal Himalayas in thewest and Bhutan Himalayas in the east. It isrelatively small but is a most significant partof the Himalayas. Known for its fast-flowingrivers such as Tista, it is a region of highmountain peaks like Kanchenjunga(Kanchengiri), and deep valleys. The higherreaches of this region are inhabited by Lepchatribes while the southern part, particularly theDarjiling Himalayas, has a mixed populationof Nepalis, Bengalis and tribals from CentralIndia. The British, taking advantage of thephysical conditions such as moderate slope,thick soil cover with high organic content, welldistributed rainfall throughout the year andmild winters, introduced tea plantations in thisregion. As compared to the other sections ofthe Himalayas, these along with the ArunachalHimalayas are conspicuous by the absence ofthe Shiwalik formations. In place of theShiwaliks here, the duar formations areimportant, which have also been used for thedevelopment of tea gardens. Sikkim andDarjiling Himalayas are also known for theirscenic beauty and rich flora and fauna,

particularly various types of orchids.

The Arunachal Himalayas

These extend from the east of the BhutanHimalayas up to the Diphu pass in the east.The general direction of the mountain range isfrom southwest to northeast. Some of theimportant mountain peaks of the region are

The Shiwalik

The word shiwalik has its origin in thegeological formation found in and arounda place called Sivawala near Dehra Dunwhich was once a headquarter of theImperial Survey and which subsequentlyestablished its permanent headquartersat Dehra Dun.

Figure 2.6 : Himalayan Mountain Complex : Cross Sectional View from South to North

South North

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Kangtu and Namcha Barwa. These ranges aredissected by fast-flowing rivers from the northto the south, forming deep gorges.

Bhramaputra flows through a deep gorge aftercrossing Namcha Barwa. Some of theimportant rivers are the Kameng, theSubansiri, the Dihang, the Dibang and theLohit. These are perennial with the high rate offall, thus, having the highest hydro-electricpower potential in the country. An importantaspect of the Arunachal Himalayas is thenumerous ethnic tribal community inhabitingin these areas. Some of the prominent ones

Figure 2.7 : Eastern Himalayas

from west to east are the Monpa, Daffla, Abor,Mishmi, Nishi and the Nagas. Most of thesecommunities practise Jhumming. It is also

known as shifting or slash and burncultivation. This region is rich in biodiversitywhich has been preserved by the indigenouscommunities. Due to rugged topography, theinter-valley transportation linkages arenominal. Hence, most of the interactions arecarried through the duar region along theArunachal-Assam border.

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Figure 2.8 : Mizo Hills

Figure 2.9 : Loktak Lake

The Eastern Hills and Mountains

These are part of the Himalayan mountain

system having their general alignment from thenorth to the south direction. They are knownby different local names. In the north, they areknown as Patkai Bum, Naga hills, the Manipurhills and in the south as Mizo or Lushai hills.These are low hills, inhabited by numeroustribal groups practising Jhum cultivation.Most of these ranges are separated from eachother by numerous small rivers. The Barak isan important river in Manipur and Mizoram.The physiography of Manipur is unique bythe presence of a large lake known as Loktaklake at the centre, surrounded by mountainsfrom all sides. Mizoram which is also knownas the Molassis basin which is made up ofsoft unconsolidated deposits. Most of the rivers

in Nagaland form the tributary of theBrahmaputra. While two rivers of Mizoram andManipur are the tributaries of the Barak river,

which in turn is the tributary of Meghna; therivers in the eastern part of Manipur are thetributaries of Chindwin, which in turn is atributary of the Irrawady of Myanmar.

The Northern Plains

The northern plains are formed by thealluvial deposits brought by the rivers theIndus, the Ganga and the Brahmaputra.These plains extend approximately 3,200 kmfrom the east to the west. The average widthof these plains varies between 150-300 km.

The maximum depth of alluvium depositsvaries between 1,000-2,000 m. From thenorth to the south, these can be divided intothree major zones: the Bhabar, the Taraiandthe alluvial plains. The alluvial plains can befurther divided into the Khadar and theBhangar.

Bhabaris a narrow belt ranging between8-10 km parallel to the Shiwalik foothills atthe break-up of the slope. As a result of this,the streams and rivers coming from themountains deposit heavy materials of rocksand boulders, and at times, disappear in this

zone. South of the Bhabaris the Taraibelt,with an approximate width of 10-20 km wheremost of the streams and rivers re-emergewithout having any properly demarcatedchannel, thereby, creating marshy andswampy conditions known as the Tarai. Thishas a luxurious growth of natural vegetationand houses a varied wild life.

The south ofTaraiis a belt consisting ofold and new alluvial deposits known as theBhangar and Khadar respectively. Theseplains have characteristic features of mature

stage of fluvial erosional and depositionallandforms such as sand bars, meanders, ox-bow lakes and braided channels . TheBrahmaputra plains are known for theirriverine islands and sand bars. Most of theseareas are subjected to periodic floods andshifting river courses forming braided streams.

The mouths of these mighty rivers also formsome of the largest deltas of the world, for

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example, the famous Sunderbans delta.Otherwise, this is a featureless plain with ageneral elevation of 50-150 m above the mean

sea level. The states of Haryana and Delhi forma water divide between the Indus and theGanga river systems. As opposed to this, theBrahmaputra river flows from the northeast tothe southwest direction before it takes analmost 90 southward turn at Dhubri beforeit enters into Bangladesh. These river valleyplains have a fertile alluvial soil cover whichsupports a variety of crops like wheat, rice,sugarcane and jute, and hence, supports alarge population.

The Peninsular PlateauRising from the height of 150 m above the riverplains up to an elevation of 600-900 m is theirregular triangle known as the Peninsularplateau. Delhi ridge in the northwest, (extensionof Aravalis), the Rajmahal hills in the east, Girrange in the west and the Cardamom hills in

Figure 2.10 : Northern Plain

Figure 2.11 : A Part of Peninsular Plateau

the south constitute the outer extent of thePeninsular plateau. However, an extension ofthis is also seen in the northeast, in the form of

Shillong and Karbi-Anglong plateau. ThePeninsular India is made up of a series ofpatland plateaus such as the Hazaribaghplateau, the Palamu plateau, the Ranchiplateau, the Malwa plateau, the Coimbatoreplateau and the Karnataka plateau, etc. Thisis one of the oldest and the most stablelandmass of India. The general elevation of theplateau is from the west to the east, which isalso proved by the pattern of the flow of rivers.Name some rivers of the Peninsular plateauwhich have their confluence in the Bay ofBengal and the Arabian sea and mention some

landforms which are typical to the east flowingrivers but are absent in the west flowing rivers.Some of the important physiographic featuresof this region are tors, block mountains, riftvalleys, spurs, bare rocky structures, series ofhummocky hills and wall-like quartzite dykesoffering natural sites for water storage. Thewestern and northwestern part of the plateauhas an emphatic presence of black soil.

This Peninsular plateau has undergonerecurrent phases of upliftment andsubmergence accompanied by crustal faulting

and fractures. (The Bhima fault needs specialmention, because of its recurrent seismicactivities). These spatial variations havebrought in elements of diversity in the relief ofthe Peninsular plateau. The northwestern partof the plateau has a complex relief of ravinesand gorges. The ravines of Chambal, Bhind andMorena are some of the well-known examples.

On the basis of the prominent relieffeatures, the Peninsular plateau can be dividedinto three broad groups:

(i) The Deccan Plateau

(ii) The Central Highlands(iii) The Northeastern Plateau.

The Deccan Plateau

This is bordered by the Western Ghats in thewest, Eastern Ghats in the east and theSatpura, Maikal range and Mahadeo hills inthe north. Western Ghats are locally knownby different names such as Sahyadri in

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Maharashtra, Nilgiri hills in Karnataka andTamil Nadu and Anaimalai hil ls andCardamom hills in Kerala. Western Ghats are

comparatively higher in elevation and morecontinuous than the Eastern Ghats. Theiraverage elevation is about 1,500 m with theheight increasing from north to south.Anaimudi (2,695 m), the highest peak ofPeninsular plateau is located on the Anaimalaihills of the Western Ghats followed by Dodabetta(2,637 m) on the Nilgiri hills. Most of thePeninsular rivers have their origin in theWestern Ghats. Eastern Ghats comprising thediscontinuous and low hills are highly erodedby the rivers such as the Mahanadi, theGodavari, the Krishna, the Kaveri, etc. Some of

the important ranges include the Javadi hills,the Palconda range, the Nallamala hills, theMahendragiri hills, etc. The Eastern and theWestern Ghats meet each other at the Nilgiri hills.

The Central Highlands

They are bounded to the west by the Aravalirange. The Satpura range is formed by a seriesof scarped plateaus on the south, generally atan elevation varying between 600-900 m abovethe mean sea level. This forms thenorthernmost boundary of the Deccan plateau.

It is a classic example of the relict mountainswh ich are hi ghl y denuded and formdiscontinuous ranges. The extension of thePeninsular plateau can be seen as far asJaisalmer in the West, where it has beencovered by the longitudinal sand ridges andcrescent-shaped sand dunes called barchans.This region has undergone metamorphicprocesses in its geological history, which canbe cor roborated by the presence ofmetamorphic rocks such as marble, slate,gneiss, etc.

The general elevation of the CentralHighlands ranges between 700-1,000 m abovethe mean sea level and it slopes towards thenorth and northeastern directions. Most of thetributaries of the river Yamuna have their originin the Vindhyan and Kaimur ranges. Banas isthe only significant tributary of the riverChambal that originates from the Aravalli inthe west. An eastern extension of the CentralHighland is formed by the Rajmahal hills, to

the south of which lies a large reserve ofmineral resources in the Chotanagpurplateau.

The Northeastern Plateau

In fact it is an extension of the main Peninsularplateau. It is believed that due to the forceexerted by the northeastward movement of theIndian plate at the time of the Himalayanorigin, a huge fault was created between theRajmahal hills and the Meghalaya plateau.Later, this depression got filled up by thedeposition activity of the numerous rivers.Today, the Meghalaya and Karbi Anglongplateau stand detached from the main

Peninsular Block. The Meghalaya plateau isfurther sub-divided into three: (i) The GaroHills; (ii) The Khasi Hills; (iii) The Jaintia Hills,named after the tribal groups inhabiting thisregion. An extension of this is also seen in theKarbi Anglong hills of Assam. Similar to theChotanagpur plateau, the Meghalaya plateauis also rich in mineral resources like coal, ironore, sillimanite, limestone and uranium. Thisarea receives maximum rainfall from the southwest monsoon. As a result, the Meghalayaplateau has a highly eroded surface.Cherrapunji displays a bare rocky surface

devoid of any permanent vegetation cover.

The Indian Desert

Figure 2.12 : The Indian Desert

Can you identify the type of sand dunes

shown in this picture?

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development of ports and harbours. Kandla,Mazagaon, JLN port Navha Sheva, Marmagao,Mangalore, Cochin, etc. are some of the

important natural ports located along thewest coast. Extending from the Gujarat coastin the north to the Kerala coast in the south,the western coast may be divided intofollowing divisions the Kachchh andKathiawar coast in Gujarat, Konkan coast inMaharashtra, Goan coast and Malabar coastin Karnataka and Kerala respectively. Thewestern coastal plains are narrow in themiddle and get broader towards north andsouth. The rivers flowing through this coastalplain do not form any delta. The Malabarcoast has got certain distinguishing featuresin the form ofKayals(backwaters), whichare used for fishing, inland navigation and alsodue to its special attraction for tourists. Everyyear the famous Nehru Trophy Vallamkali(boat race) is held in Punnamada Kayal inKerala.

As compared to the western coastal plain,the eastern coastal plain is broader and is anexample of an emergent coast. There are well-developed deltas here, formed by the riversflowing eastward in to the Bay of Bengal. Theseinclude the deltas of the Mahanadi, the

Godavari, the Krishna and the Kaveri. Becauseof its emergent nature, it has less number ofports and harbours. The continental shelfextends up to 500 km into the sea, whichmakes it difficult for the development of goodports and harbours. Name some ports on theeastern coast.

The Islands

Figure 2.13 : Coastal Plains

To the northwest of the Aravali hills lies theGreat Indian desert. It is a land of undulatingtopography dotted with longitudinal dunes

and barchans. This region receives low rainfallbelow 150 mm per year; hence, it has aridclimate with low vegetation cover. It is becauseof these characteristic features that this is alsoknown as Marusthali. It is believed thatduring the Mesozoic era, this region was underthe sea. This can be corroborated by theevidence available at wood fossils park at Aakaland marine deposits around Brahmsar, nearJaisalmer (The approximate age of the wood-fossils is estimated to be 180 million years).Though the underlying rock structure of thedesert is an extension of the Peninsular

plateau, yet, due to extreme arid conditions,its surface features have been carved byphysical weathering and wind actions. Someof the well pronounced desert land featurespresent here are mushroom rocks, shiftingdunes and oasis (mostly in its southern part).On the basis of the orientation, the desert canbe divided into two parts: the northern part issloping towards Sindh and the southerntowards the Rann of Kachchh. Most of the riversin this region are ephemeral. The Luni riverflowing in the southern part of the desert is of

some significance. Low precipitation and highevaporation makes it a water deficit region.There are some streams which disappear afterflowing for some distance and present a typicalcase of inland drainage by joining a lake orplaya. The lakes and the playas have brackishwater which is the main source of obtaining salt.

The Coastal Plains

You have already read that India has a longcoastline . On the basis of the location andactive geomorphological processes, it can be

broadly divided into two: (i) the western coastalplains; (ii) the eastern coastal plains.

The western coastal plains are an exampleof submerged coastal plain. It is believed thatthe city of Dwaraka which was once a part ofthe Indian mainland situated along the westcoast is submerged under water. Because ofthis submergence it is a narrow belt andprovides natural conditions for the

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Figure 2.14 : An Island

There are two major island groups in India one in the Bay of Bengal and the other in theArabian Sea. The Bay of Bengal island groupsconsist of about 572 islands/islets. These aresituated roughly between 6N-14N and92E -94E. The two principal groups of isletsinclude the Ritchies archipelago and theLabrynth island. The entire group of island isdivided into two broad categories theAndaman in the north and the Nicobar in thesouth. They are separated by a water body

which is called the Ten degree channel. It isbelieved that these islands are an elevatedportion of submarine mountains. However,some smaller islands are volcanic in origin.Barren island, the only active volcano in Indiais also situated in the Nicobar islands.

Some important mountain peaks inAndaman and Nicobar islands are Saddlepeak (North Andaman 738 m), MountDiavolo (Middle Andaman 515 m), MountKoyob (South Andaman 460 m) andMount Thuiller (Great Nicobar 642 m).

The coastal line has some coral deposits,and beautiful beaches. These islands receiveconvectional rainfall and have an equatorialtype of vegetation.

The islands of the Arabian sea includeLakshadweep and Minicoy. These are scatteredbetween 8N-12N and 71E -74E longitude.These islands are located at a distance of280 km-480 km off the Kerala coast. Theentire island group is built of coral deposits.There are approximately 36 islands of which

11 are inhabited. Minicoyis the largest island

with an area of 453 sq. km. The entire groupof islands is broadly divided by the Eleventhdegree channel, north of which is the AminiIsland and to the south of the CanannoreIsland. The Islands of this archipelago havestorm beaches consisting of unconsolidatedpebbles, shingles, cobbles and boulders on theeastern seaboard.

On 26 December 2004, the Andaman and Nicobar islands experienced one of the mostdevasting natural calamity. Can you name the calamity and identify some other areaswhich were adversely affected by the same calamity? What was its major consequence?

1. Choose the right answer from the four alternatives given below.

(i) In which part of Himalayas do we find the Karewa formation?

(a) North-eastern Himalayas (c) Eastern Himalayas

(b) Himachal-Uttarakhand Himalayas (d) Kashmir Himalayas

(ii) In which of the following states is Loktak lake situated?

(a) Kerala (c) Manipur

(b) Uttarakhand (d) Rajasthan

(iii) Which one of the water bodies separates the Andaman from the Nicobar?(a) 11 Channel (c) 10 Channel

(b) Gulf of Mannar (d) Andaman Sea

(iv) On which of the following hill range is the Dodabeta peak situated?

(a) Nilgiri hills (c) Cardamom hills

(b) Anaimalai hills (d) Nallamala hills

2. Answer the following questions in about 30 words.

(i) If a person is to travel to Lakshadweep, from which coastal plain does heprefer and why?

EXERCISES

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(ii) Where in India will you find a cold desert? Name some important ranges ofthis region.

(iii) Why is the western coastal plain is devoid of any delta?

3. Answer the following questions in not more than 125 words.(i) Make a comparison of the island groups of the Arabian Sea and the Bay of

Bengal.

(ii) What are the important geomorphological features found in the river valleyplains?

(iii) If you move from Badrinath to Sunderbans delta along the course of theriver Ganga, what major geomorphological features will you come across?

Project/Activity

(i) Make a list of major Himalayan peaks from the west to the east with the helpof an atlas.

(ii) Identify the major landforms of your state and analyse the major economicactivity practised by the people in each landform.

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