PHYSIOGRAPHIC REGIONS

India was part of Gondwana land, the great southern continent of the world, which broke up after the close of Palaeozoic time period into huge continental blocks. These crystal slabs gradually drifted apart to form the present day continents of Africa, Australia, Antarctica, India and South America. The Talchir Boulder Bed of glacial origin indicates that during the Permo-Carboniferous period, India must have been situated far away from the equator. When Gondwana land was fragmented, the Indian continent drifted northwards. This movement caused the Peninsular Indian block to plough into the Mediterranean Sea of Tethys causing the pile of geosynclinal sediments there to buckle up. There is evidence to show that the northern borders of the peninsular block have been overridden by the much younger mountain ranges- the Himalayas. The doubling of the sialic crust is responsible for the formation of the world’s most elevated table land in the Tibet, the so called “Roof of the World”. The Himalayan ranges continued to be uplifted by a series of very severe convulsions. These major crustDIRECTION movements were responsible for the sharply demarcated three-fold structural physiographical divisions of India, each with its own characteristic features- the Pen- insula, consisting mainly of Precambrian rocks in a stable shield area; the Extra-Pen- insula, forms a system of folded and faulted sedimentary beds which were deposited in a Mediterranean sea; and an intermediate tectonic’ rift valley known as the Indo-Gangetic trough which is now filled with a thick deposit of alluvium. Northern Mountain Range: High relief, snow-capped summits, deeply dissected topography, antecedent drain- age and complex geological structure give a distinct character to this geomorphic unit. The average width of this series of semi parallel or converging ranges varies from 160-400 km. The length of the central axial angle is about 2500 km. The slope is steep towards the plain of India (within a horizontal distance of 150 km the vertical rise is over 8 km) and towards the north, it merges gently with the edge of the Tibetan plateau. The ranges of Arunachal Pradesh, Assam and Bhutan make up the Eastern Himalaya. The Central Himalayas covers the mountain of Nepal and the Kumaon, Punjab and Kashmir mountains are included in Western Himalayas. The north eastern ranges on the Assam-Myanmar border strikes north south through Myanmar in an arc bulging towards the west. Beyond the ranges of the Western Himalayas lie the North

DIRECTIONDIRECTION Main Examination 1 INSTITUTE FOR IAS EXAMINATION western Ranges stretching over Afghanistan and Pakistan culminating in the east- west trending hills of Baluchistan in the extreme south. The Himalayas constitute the highest mountain system of the world. They extend for a distance of about 2,500 kms, having a breadth of about 150 to 400 km, and cover an area of about 500,000 sq km. They are typically tectonic in origin, having been uplifted during the Tertiary time period from the bed of the great Mediterranean Sea, the Tethys. The Himalayas took probably several million years to attain to their present heights. These uplifting movements of these ranges have not ceased yet, as this region is still unstable and susceptible to earthquakes. During the slow process of mountain formation, by folding and upheaval of the rock beds, the old rivers kept very much to their own channels, and hence are seen to cut across these ]nightly ranges. For example, the west-flowing river Sutlej has cut across a high range and runs through a steep-sided valley. The Himalayan chain has an arcual layout with the convex side facing the Indo Gangetic plain. The southern boundary is clearly demarcated by the 300 m contour line in the west, and the 150 m-contour line in the east. From the foot- hills the Himalayas rise rapidly northwards to over 8,000 m within a short distance. The heights are covered with perpetual snow which feeds the valley glaciers, but the greater part of the Himalayas lies below the snow-line and is dissected by fluvial erosion.DIRECTION The Himalayan Mountains can be divided into three parallel or longitudinal zones, each with definite geographical features - the Great -Himalayas (Himadri) in the north, the Lesser Himalayas (Himachal) in the middle, and the Outer Himalayas (Shivalik) in the south. Himadri The Great Himalayas or the Himadri is a majestic range of mountains which rises above the lower limit of perpetual snow. The average elevation of the range is about 6,000 m, and some of the highest peaks of the Himalayas are situated in this range - Mount Everest (8.848 m); Kanchenjunga (8,598 m); Dhaulagiri (8,172 m): Nanga Parbat (8.1 26 m); Nanda Devi (7,8 17 m)and other peaks. This great mountain chain at its western and eastern ends terminates with sharp syntaxical bends. The northern slopes of the Great Himalayan rulge descend gradually on to some prominent river valleys which run parallel to each other for long distances. The Himachal The Lesser Himalaya or the Himachals are a massive mountainous tract, 75 km wide. Its average elevation is 4500m .The range is divided into many parallel running ranges as Pir Panjal, Dhaula Dhar, Mussouri, Kumaon ranges.

DIRECTIONDIRECTION Main Examination 2 INSTITUTE FOR IAS EXAMINATION The Shivalik The Outer Himalaya or the Shivalik forms the foothills of the Himalayan system, and lies between the Lesser Himalaya and the plains of India. Its width varies from 1 0 to 50 kms, and the average elevation is about 600m. These ranges are composed of upper Tertiary sedimentary river deposits. They are folded and faulted by earth movements which mark the latest phase of the Himalayan uplift. The ranges descend northwards into flat valleys called duns which are intensively cultivated and densely populated The Himalayas as a great orogenic, arcuate belt possesses strict linear parallelism in lithology, tectonism and physiography. However, in the six fold division of the Himalayas, the individual segments are transverse to the Himalayan ranges. In the northwestern part in the Kashmir Himalaya, where the width of the mountain range is close to 500 kilometers it is possible to discuss the main longitudinal ranges individually but east- wards, particularly from the Sikkim Himalaya onward, the true longitudinal ranges cannot be described separately but instead they are assembled together. Kashmir Himalaya The Himalayas are at the widest in Jammu and Kashmir province and hence its four linear ranges: the Siwalik, Lesser, Central and Trans (or Tethys)-Himalayan Ranges are DIRECTIONdiscernible individually in this north-western most province of India, covering 500 kilometers in width and 700 kilometers in length. The southern ranges of the outer Himalayan Siwalik belt, which coincide with the Jammu and Poonch regions, is made up of Tertiary and early Pleistocene time molassic sediments and they present a rug- gedly youthful topography with a height of not more than 1,500 meters. This sub-Hima- layan zone ends in the MBT in the north, from where the Pir Panjal Range rises. In the Pir Panjal Range there exists two passes: Pir Panjal (3,640 meters) and Banihal (2,740 meters) Pass. The Lesser Himalaya (separated by the MBT) with an elevation rang- ing from 1,500 to 3,000 meters has a comparatively mild topography which also in- cludes a great synclinal basin, the Vale of Kashmir, which is 135 by 40 kilometers. The latter with a floor in the Jhelum thalweg at 1,500 meters height is topographically a floodplain with intensive landuse and human occupance. The Central Himalayan Range may be taken as commencing from Zozi La (3,529 meters) Pass, beyond Sonemarg, where the Main Central Thrust, MCT, brings a plane of abrupt cataclastic change in metamorphism, strong mylonitization and schuppen structure. Topographically, the Central Himalaya, a really high ground (3,000 to 8,000 meters) is pierced into extremely rugged immature topography (Nanga Parvat, 8,126 meters) with a homoclinal structure of early Pre-cambrian metamorphics. To the north of the Central Himalaya,

DIRECTIONDIRECTION Main Examination 3 INSTITUTE FOR IAS EXAMINATION there stretches the vast fossiliferous sedimentary realm of the Trans (or Tethys)- Himalaya, the fourth domain of the Himalaya. This Trans-Himalaya is made up of sunclinorarily deformed huge piles of sediments deposited in the Tethys Sea and its precursor. With a floor in the Indus thalweg at Leh at 3,505 meters, the structures of folds tightened northwards from the upright isoclinal folding to vertical, strongly sheared recumbent folds and imbricating thrusts so that finally the Himalayas get separated from the Tibeto-Karakoram world of the continental block of Central Asia by a series of deep mantle-reaching faults. These truncated the Ladakh and Zaskar Ranges obliquely and formed the Indus-Tsangpo Suture Zone, ITSZ. This zone has been des- ignated as the main mantle thrust in which the ophiolites, commonly foliated, deformed and serpentinized have been obducted and it represents the Tethys oceanic crust as well as the upper mantle material. This ITSZ sharply and dramatically separates the vast sedimentary realm of the Tethys Himalaya from the Tibeto-Karakoram world of the Eurasian continental block. Punjab Himalaya The territorial arrangement of the Punjab Himalaya is the separation from the Kishtwar area of the Kashmir Himalaya by the Chandra (or upper Chenab) Valley from which this Himalayan region stretches north eastwards for about 570 kilometers to the Satluj river.DIRECTION In this domain there is the usual longitudinal arrangement of the parallel Hima- layan ranges. The Siwaliks here have a remarkably linear crest at 610 to 915 meters height but since this area in the northern districts of Punjab is largely deforested, the barely coherent sandstone rocks are savagely eroded into ravines particularly in the 130 kilometers long stretch of Hoshiarpur district. In this area overlying of the Siwalik rocks on the recent alluvium by the Son thrust indicates neotectonic activity. The Lesser Himalaya in this region (between the Chenab on the west and the Jammu on the east) has a tangled mass of intermediate spurs like the Kishtwar and Dhauladhar Ranges from a height of 2,155 to 4,570 meters. The former separates the long northwest to southeast extension of the Chenab (in the upper valley) from the Ravi and the latter separates the longitudinal sections of the Ravi and Beas. The topography of the Satluj and Jamuna which defiles further east is highly confused in detail with the major Jutogh- Chail thrusts that cover the complex and strongly folded anticlinorial autochthon of the Pre-cambrian sediment and now best seen in the Larji window in the Beas Valley. Finally, the Central Himalaya is on the whole much lower, the high peaks are rare in this section (with the great cleft of the Satlej cutting across the Zaskar and the Central Himalaya at 1,525 to 2,121 meters) and much more broken here than either in Kash-

DIRECTIONDIRECTION Main Examination 4 INSTITUTE FOR IAS EXAMINATION mir or further east in the Kumaon Himalaya, Rohtang (3,978 meters) and Bara Lapcha (4,891 meters) are the important passes in this section. Kumaon Himalaya Broadly speaking, the Kumaon Himalaya stretches for about 320 kilometers between the Tons feeder of Yamuna and Kali rivers (the feeder of Sharda), the latter forms the western boundary of Nepal. The region thus includes the Himalayan basins of the Yamuna, Ganga, Ramganga and Sharda from west to east. The area raises abruptly from the fans of the piedmont (bhabar) belt, the junction of which is designated as the Himalayan frontal Fault, HFF. The latter cuts the folds and thrusts with steep reverse faults which gives rise to a progressively deepening depression in front of the Siwaliks with rising hills but now sedimented to develop duns, for example Dehradun Valley, one of the world’s largest parabolic prisms. Further northwards, the steeply inclined Krol thrust of the Main Boundary Fault sharply cuts the youthful autochthonous Ceno- zoic sedimentary zone of the Siwalik from the much older Lesser Himalayan Range. Most of the Lesser Himalayan Range in the Kumaon Himalayan region consists of a maze of ridges and a highly dissected country (1,230 to 2,135 meters) of three major nappes – the Krol-Berinag-and-Almora thrust – which cover the complex, strongly folded, broadly anticlinorial autochthon of the Precambrian sediments. On the outer flanksDIRECTION of this region lie Chakrata, Mussoorie, Ranikhet, Almora and Nainital. The Cen- tral Himalaya in Kumaon is a huge tectonic slab rising to a magnificent series of gla- cier-garlanded peaks, for example Trisul (7,120 meters), Santopanth (7,084 meters), Gangotri (6,614 meters), Shivling (6,638 meters) of the Kedarnath-Badrinath group (6,614 to 7,120 meters), Nanda Kot (6,898 meters) and finally Panchuli (6,895 meters) at the extreme northwest corner of Nepal. Sikkim Himalaya The Himalayas continue from River Kali to the Singhalila Ridge on the east for more than 880 kilometers through Nepal in its most stupendous form (having the world’s highest point, Mount Everest, 8,840 meters or 29,008 feet high). Between the Singhalila Ridge on the west and River Rangit is the hour-glass shaped little geographic domain of Darjeeling Hills on which the formations and metamorphosed equivalents spread of the higher ranges of Sikkim Himalayas are thrust. The mountain torrent of Tista in its descent from the Sikkim Himalayas cuts the Darjeeling Ridge (2,135 to 2,440 meters) in a narrow gorge running west of Kalimpong at Sevok bridge to spill on to the plain in a vast alluvial fan, rearmed with old courses known as the dooars (equivalent to terai in Nepal) and spread largely over Jalpaiguri district. The resting of the Pre-cambrian crystallines upon this alluvial fan of the Tista at places suggests also that the Siwaliks

DIRECTIONDIRECTION Main Examination 5 INSTITUTE FOR IAS EXAMINATION in this part of the Eastern Himalayas are not developed and in their place a band of steeply thrust Gondwana rocks are observed along the whole length of the foothills of the Nepal Himalaya extending through Darjeeling and Sikkim into the frontal thrust regions of the Arunachal Himalaya. All along the foothills of the Darjeeling Himalaya these Darjeeling Damudas are overthrust in the area as tectonic relief and this thrust zone coincides with the Main Boundary Thrust, MBT. Thus the Darjeeling Hills not only show the imbricating sheets of tectonic slices leading to schuppen structure like in the Western Himalayas but they also indicate the thrusting by the Gondwana conglomer- ates (for example, Damuda rock) from the south. The important peaks of Darjeeling Hills are Sandakphu (3,630 meters), Phalut (3,596 meters), Saborgam (3, 543 meters) and Senchal (2,615 meters).The high hills of Darjeeling on the west form a mountain cleft which is in Sikkim and the region itself is in effect all but an enclosed basin be- tween Singhalila and the Donkhya Ranges. This part of the Darjeeling Himalaya in Sikkim is occupied by River Lachen, the mountain torrent of the Tista along the axis of overturned anticline at the core of which lies the Kanchenjunga massif, 8,579 meters high, the third highest point in the world and the highest in India. A 50 kilometers long north-south dissected domal uplift of this massif dominates this Sikkim Himalaya. The Central Himalaya in Sikkim is simply built, being characterized by open folding rather thanDIRECTION the intense homoclinal folding in Western Himalaya) which make it the most well known and easily accessible section of the Himalayas. Arunachal Himalaya East of the Kanchenjunga, there is a gap in the Central Himalaya and little is known about the high Himalaya further east in Bhutan and Arunachal where the crest barely reaches 6,400 meters. Arunachal is the easternmost part of the Himachal where upto Dihang-Dibong-Lohit confluence, a little beyond Sadiya, the Himalayas maintain their west to east strike but mountains in the form of ridges curve around the Sino-Indian- Burma Plateau to turn north-south. The Lohit river basin forms the southeastern boundary of the Arunachal Himalaya. At this eastern end of the Central Himalaya is Namche Barwa (7,757 meters), the highest peak east of Kanchenjunga. The wild Dihang cuts a gorge, some 5,500 meters deep, in hair-pin shaped bends below Namche Barwa to link the Tibetan Tsangpo with the Indian Brahmaputra River. Like the Daling series in the Darjeeling Himalayan region, the Lesser Himalayan nappes in the Arunachal are also involved in very severe deformation of the Pre-cambrian Gondwana rocks, result- ing in the spectacular shuppens, for example the Aka, Daphla, Miri, Abor and Mishmi hills in the foothill zone. Again, like in other parts of the Eastern Himalayas, here also the central Himalayan range is characterized by open folding and much less relief.

DIRECTIONDIRECTION Main Examination 6 INSTITUTE FOR IAS EXAMINATION Since this easternmost Himalaya as a rampart overlooks the 640 kilometers long Brahmaputra Valley closely, the spread of the alluvial cone is restricted because of the progressively deepening Subansiri basin which appears to be sinking parri passu. Purvanchal Himalaya In the northeastern margin of the Arunachal province, the mountain ranges of the Himalayas bend topographically (but not structurally) in the form of a spectacularly sharp V-shaped re-entrant by the north-northwest to south-southeast trending Lohit thrust (which is the Main Boundary Thrust, MBT in the area) wrapping the tightly packed parallel ridges and valleys of the Patkai-Naga. They extend beyond the region as Arakan Ranges in a linear north-northeast to south-southwest trending belt of 240 kilometers width. This trend of the ridges and valleys have apparently given a mild bulge to this region towards the west. This belt, formed of the upper Cretaceous to Eocene flysch and molasses sediments of sandstones, limestones and shales, has severe deformation leading to the Tertiary successions and into multiple thrust sheets of schuppen character in the northern part (Nagaland-Manipur). In the southern part, in Tripura and Mizoram, the folded structure is a synclinorium consisting of broad syn- clines and tight-faulted anticlines. This structural characteristic makes the region tight- packed with north-south aligned ranges defined by knife-edged parallel valleys. The drainageDIRECTION system in this Purbachal Himalaya, particularly in Mizoram, shows an ex- traordinary trellis pattern of the Jura type. Topographically, the Purbachal Himalaya is the lowest among all the six Himalayan regions discussed here since the ridges in this region rarely exceed 2,135 meters though Saramati in the Naga Hills on the Indo- Burma border attains (3,826 meters) height, carrying snow at the summit occasion- ally. Starting from the north, Dapha Bum of the Mishmi Hills is the highest peak (4,579 meters high) not only of the Lohit district but of this Purbachal Himalaya also. (Con- sider to be part of Himadri) Again, in Nagaland, the Barail Range piercing from the southwest via the Cachal Hills, runs upto Kohima with its highest peak, Japavo (2,995 meters) lying to the south of the town. The general elevation of the Purbachal Himalaya increases towards the northeast and the altitudinal range of 900 to 2,100 meters cov- ers a large part of Nagaland and Manipur. The Manipur Hills make an oval rim enclos- ing the Imphal Valley which is an oblong shallow saucer stretching for 57 kilometers north-south and 32 kilometers east-west with the Loktak Lake occupying its lowest part. The region ends in the south with the Luchai (or the Mizo) Hills which in Mizoram exhibit an alternate arrangement of parallel ridges and valleys within a height range of 150 and 900 meters though peaks of over 1,500 meters elevation are not rare. A series of long-drawn sharp edged spurs from the Mizo Hills pierce the Tripura and

DIRECTIONDIRECTION Main Examination 7 INSTITUTE FOR IAS EXAMINATION Cachar region – the latter is a low lying plain at 150 meters height. This area is virtually a part of the Surma Valley (downstream in Bangladesh), built up by detrital materials. Due to the lack of sufficient slope, the surface is dotted with a number of swamps and marshy tracts. Plateau: It is in the shape of an inverted triangle occupies the greater part of central India and the Deccan with typical landscape of extensive flat or rolling plains at altitudes from 300 m to 1000 m. In central India, the Malwa and Vindhya plateau (scarp land) on the Vindhyan Mountain range on the south and decline gently northwards. The topography of Eastern plateau is diversified, ranging from low lying Mahanadi basin to undulating plateau of Baghelkhand, Chotanagpur, Dandakarnaya. The Maharashtra plateau is formed entirely of basalt and the plateau of Karnataka, Telengana are composed of Archean gneises. The hills in India are either remnants of worn down mountains as Aravallis, Satpura, Eastern Ghats or dissected plateau excarpment as Vindhyan hills or Sahyadri along west coast. Peninsular plateau is recognized to be the part of ancient Gondwanaland. It thus rep- resents one of the significant examples of shield of the world. Developed in Azoic, it incorporates Paleozoic reconstruction and Cenozoic modifications. The triple tectonicDIRECTION characteristics of India is individually justified in this relief thereby. As per the present relief profile in general, this shield has reached old stage of cycle of erosion. Its general configuration is that of a rolling Plateau with isolated relict hills in the central part and chain of hills surrounding it. Physiographically, this relief is divided on the basis of both location as well as geological structure. The central highlands include the Aravallis range, the Vindhyans and the Satpuras. These relief features belongs to the Paleozoic era. Aravallis are majorly made up of limestone, dolomite deposited in the geosyncline. It also incorporates metalliferous minerals as the reference of Azoic construct. Extending for 800 km, this range registers an increase in height towards south. It is Gurushikhar that represents the highest peak of range. As water divide, it demarcates inland seasonal drainage Banas to its east. The Vindhyan range though represents limestone dominated construct as Aravalli, it is Paleozoic block. Like Aravallis, it has Cenozoic basaltic modification towards its west covering consider- able stretch in central India with average elevation of 300 m. The main features of the region are scarps of Vindhyan sandstone. The range also includes Bandher plateau, Kaimur hills and Baghelkland as its physiographic constituents. It slopes gently towards the north and abruptly towards south. The Panna hills forms the diamond bearing horizon. This entire belt structurally belongs to Archean and Purana, Upper

DIRECTIONDIRECTION Main Examination 8 INSTITUTE FOR IAS EXAMINATION Pre-Cambrian construct. South of Vindhyans, lies narrow valley of Narmada, the example of rift valley. The river flows westwards forming several waterfalls as Dhuandhar falls near Jabalpur. The Satpura range also forms the example of Paleozoic block. More extensive and high elevation, this block is incorporating Cenozoic basalt con- struct. Generally, this range has elevation between 600-900mts extending between Narmada and Tapi rift valleys. It extends from Rajpipla in Gujarat to Maikala range in Chhattisgarh. The Gwaligarh range, Betul Plateau, Mahadeo hills are the other physi- ographic constituents. Dhupgarh in Panchmarhi is the highest elevation. Amarkantak represents the radial drainage of Narmada, Hasdo and Johilla rivers. South of river Tapi, Satmala and Ajanta ranges are identified. Majorly made up of Upper Precam- brian construct, it has significant basaltic construct of Cenozoic. The Azoic relief in- cludes crystalline plateau with major structural and relief features. The Deccan plateau is a triangular plateau extending between Eastern and Western Ghats, south of river Tapi. The relief is dominated with denuded hills and dissected plateaus. The Maharashtra plateau and Malnads of Karnataka has major basaltic construct de- veloped over Archean Gnesis and Schist as well as Dharwar series. The plateaus of Telengana and Dandkarnya are majorly the Archean structure with Dharwar/Cuddappah structure. The gradient of these tablelands are generally towards east. Western Ghats demarcatesDIRECTION the western boundary. Also called Sahyadris, these mountain escarp- ments represents continuous profile barring Thalghat, Bhorghat gaps. Acting as water divide between Sahyadri basin and rest of peninsular basin; it is physiographically extending till Nilgiris. The Phalghat gap and Shenkotta gaps further forms the divides. Though considerably narrow, Sahyadris have Balaghat and Harishchandra ranges in Maharashtra along with Baba Budan, Melagiri, Schechacalam hills and Bangalore- Mysore Tableland as extensive parts in Karnataka. The structural characteristics of the Sahyadris are similar to that of peninsular plateau with Archean, Dharwar and basaltic Cenozoic construct. The Eastern Ghats are more low-lying and dissected owing to riverine deposits. Mahendragiri, Nallamalla, Palkonda are the significant constituents. Tikarpara, Nayagarh forms the discontiguous and Mahendragiri due to Brahmani, Mahanadi and Rushkuliya rivers. It is delta deposits of Godavari and Krishna that demarcates Nallamalla and Mahendragiri. The Penneru river incorporates the tributary network that forms the cause of Erramalla, Velikonda, Palkonda and Nagari hills. The southern hills as Javadi, Sheveroy and Panchimalai hills demarcate the plains of Tamil Nadu. Structurally it though has Azoic built, it has Cuddappah structure. The Malwa–Bundelkhand tableland has the similar geological construct to that of Deccan trap. It however has flat topped feature and it is majorly dissected by peninsular tribu-

DIRECTIONDIRECTION Main Examination 9 INSTITUTE FOR IAS EXAMINATION taries of Yamuna. The Chottanagpur plateau though is the extension of shield; it repre- sents lack of Cenozoic construct. The Hazaribagh Plateau, Garjat hills, Ramgarh hills and Rajmahal hills are the physiographic units. The far eastern uplands are discontiguous extension of Chottanagpur plateau. It however is distinguished on the grounds of more lateritic construct. On to the extreme west is the Kathiawar upland, known for its basaltic construct. It has Gir range, Girnal hills, Barda and Mandvi hills as its physiographic subdivides. Radial drainage forms its characteristics also with Bhader, Shetrunji, Bhogawa and Machhu rivers. Plains Plains are relatively low lands moderately undulating or flat. Plains occurring on con- tinental borders are known as coastal plains. Interior plains are those which are situ- ated in the interior of a continent. The plains of India are of great importance from historical point of view, as they have been the craddles of ancient cultures. Almost all the different types of plains are found in the vast Indian subcontinent, which are briefly described as following Great Plain of India Between the Himalayan Range in north and plateau to south, lays the Great Plain of India. These are aggradational plains, formed by the work of river systems, Indus, GangesDIRECTION and Brahmaputra. The arcuate plain extends for the length of 3200 km (in India it is 2400km). Its average width varies between 150-300 km. Covering about 7.8 lakh km², its northern boundary is much specified by Shiwalik though the southern boundary is quiet irregular. Geologically, these plains were deep depression and were filled up by the both alluvium of peninsular and Himalayan Rivers. These plains are categorized on the basis of the soil structure. The Bhaber is a narrow belt of about 8-16 km of width at the foot of Shiwalik with continuity from Rabi to Tista Rivers. These are riverine deposits, mainly of gravel and unsorted sediments. These are thus, the northern boundary of the plain and is lacking in cultivation potentiality. The Tarai is 15-30 km wide marshy land running parallel to Bhaber. As the braided streams domi- nates the landscape, thick stand of deciduous trees are typical feature of the plain. Towards east, wet climatic conditions and towards west, large streams descend makes the Tarai belt homogenous in its characteristics. The Bhanger is an old alluvium of these plain, deprived by annual renewal. To the arid west land, it reveals calcareous structure called Kankar. These mark universal presence in the alluvial terraces. The Khader on the contrary are composed of new alluvium. These are thus confined to the present flood prone river basins. It is Khader that avails the most fertile characteris- tics, as per the annual renewal of soil and spatially mix up with coastal delta deposits

DIRECTIONDIRECTION Main Examination 10 INSTITUTE FOR IAS EXAMINATION in West Bengal. On the basis of climatic conditions and riverine course, the great plains are divided into several regional units. The units reveal the characteristic details of the Great Plains. The Trans Gangetic plains are confined to north – western extents of the plain where the arid, semi arid climatic conditions prevails. Physiographically, it thus includes the arid plains of Thar Desert and Rajasthan bagar to west and Sutlej – Yamuna plains in east. The Thar desert – Maruasthali, is typically recognized with the shifting sand dunes – Dharians. The temporary playa lakes Dhands and the temporary furrows Dharos forms the other characteristic features. Comparatively towards Aravalli range bagar, sandy alluvium of luni river network avail rohi, the fertile land. The luni basin is characterized also with the saline lakes availing inland drainage – Didwana, Sambhar are the prominent examples. The semi arid trans-Gangetic plain are characterized by the doab soil. Bist and Bari doabs, coarser alluvium are the most significant characteristics. The chos are the braided streams descended from Shiwalik. Betlands and Dhayas are the flood plains and bluffs known for their agricultural value. Being semi arid, these alluviums are influ- enced by calcification and thus are kankar rich. The Bhiwani Bagar forms the inland drainage basin of Ghaggar in Haryana. Dry for most part of the year, this river basin incorporatesDIRECTION saline tracks also. The Gangetic plains are the largest constituent of the northern plains of India. It stretches from river Yamuna to river Hooghly. Apart from Himalayan Rivers, it includes the deposition of peninsular streams also. The over all gradient of the plain is from NW to SE. It is on the basis of riverine course and climatic conditions that these plains are categorized into three, physiographic units. The upper Gangetic plains are sub- humid plains politically confined in Uttar Pradesh. Generally, these plains are doabs, divided into Rohilkhand and Awadh plains. Mainly these plains are characterized by sandy alluvium, bhurs and kols. The Rohilkhand plain is dominated by Ganges – Yamuna doab and the low lying Awadh plain has Ghaghra, the principal stream. The mid-Gangetic plains are humid plains of silty alluvium. These plains are divided into two parts, demarcated by Ganges flow. The northern plains are Mithila drained by Gandak, and Kosi and southern plains are Magadh drained by river Son, Punpon and Badna. The Magadh plains are dotted by azoic shield thus chaurs, fresh water lakes represents the prominent characteristics. For the Rajmahal hills, these lakes are called Kavartals. The lower Gangetic plains, have clayey alluvium with par moist conditions. The barinds and the coastal delta thus are the two most important physi-

DIRECTIONDIRECTION Main Examination 11 INSTITUTE FOR IAS EXAMINATION ographic divides. The sub-Himalayan plains however incorporates duars, the alluvial cone and the plateau, plain have developed Rahr plains. The Brahmaputra plains are 720 km long narrow plains between Dhubri and Sadiya. Large number of tributaries of Brahmaputra makes the plain characterized with me- anders, Oxbow lakes. The majuli riverine island forms the important feature at the confluence of Disang and Subansiri. The Indian plains, with renewed soil makes the fertile lowlands, sustaining the food requirement of the country. Its year-round cultiva- tion is also favoured by Himalayan barrier restricting polar winds. The coastal plains are the alluvial plains of varying width. East plain is broader with deltas of all the major peninsular river whereas west is narrower excepting for its northern extension, where it has broader delta deposits of Sabarmati and Mahi. These plains are referred to have attained their narrow characteristics due to subsidence during Paleozoic. The Indian Ocean was formed when Gondwanaland broke up and the different parts moved apart. Breakup of Gondwanaland started in the Africa-Tasmania-Victoria land region according to F. Ahmad. India-Australia-Antarctica started sundering apart from Africa in the Cretaceous Period and the Carlsberg Ridge was formed. Soon after, however, India-Australia-Antarctica started rotating in an anti-clockwise sense inde- pendentDIRECTION of the Carlsberg Ridge. Widespread faulting occurred in peninsular India and it extended to Western Australia. Thereafter, Antarctica-Australia drifted away from India by crustal sliding and after that Antarctica broke away from Australia in the Oli- gocene time and moved into its present frigid zone. All the waters between these land masses formed the various parts of the Indian Ocean. With the breakup of Gondwanaland during the later Mesozoic era the Indian Peninsula seems to have acquired its main outline only about the beginning of the Cretaceous, except for its northwestern part which already had a coastline in the Permo-Carboniferous. India probably separated from Madagascar in the Upper Cretaceous when the western coastline developed. The east coast went straight up to Upper Assam during the Up- per Mesozoic and Lower Cenozoic. The truncation of this long coastline to give it the present reduced length occurred in the late Tertiary when the Bengal Bain started to develop and separated the Shillong Plateau from the main mass of the Peninsula. It thus appears that the two coasts of India evolved at different times in geological his- tory. The coasts that surround the Indian Peninsula are of the longitudinal Pacific type which border mountain chains. The major portions of the Indian coasts are either stable or advancing, being built into the sea by deltas or estuaries. However, an example of the retreating type of coast is found near Rameswaram where the land surface

DIRECTIONDIRECTION Main Examination 12 INSTITUTE FOR IAS EXAMINATION connecting the southern tip of India with Sri Lanka was drowned during the Quaternary times. The submerged link is not more than 13 m deep, and a narrow land bridge between the two countries is now represented by the Pamban Island and the Mannar Island connected by the Adam’s Bridge lying midway between the two islands. The Adam’s Bridge is a drowned ridge whose crests are exposed during low tides. The east coast is much broader than the west coast; the former presents a more smooth outline than the latter, though the indentations in the west coast are not prominent. The East Coast The east coast of India starts from the edge of the Ganga delta and extends right through to the southernmost tip of the Peninsula at Kanyakumari (Cape Comorin) facing the Bay of Bengal. The coast is mostly of the emergent type, that is, it is regular in outline and is characterized by offshore bars, fine sea beaches, sand ridges and lagoons. Most of the great rivers of India, barring a few notable exceptions, have their mouths on this coast. The coastal plain on the east is much wider than that on the west. Here the narrow strip of beaches is fronted by rows of sand dunes, broken by a num- ber of lagoons. The surfaces of the Kanthi Coastal Plain of West Bengal and the Balasore Coastal Plain of Orissa are more or less terraced, and the Mayurbhanj PlainDIRECTION on their hinterland is partly aggradational and partly erosional. The Nadhra Plain is much narrower and is flanked by outlying spurs of the Eastern Ghats. South of the Krishna delta, the coastal plains broaden again and are successively designated as the Nellore, Tamil Nadu and Tuticorin Coastal Plains. They are mostly alluvial plains with belts of sand dunes in between. The low level and the smooth contours of the tract of country which lies in front of the east coast below the Mahanadi suggest that it was a submarine plain which has emerged from the waters at a comparatively late date. Behind this coastal belt are the gneissic highlands of the mainland, the Eastern Ghats, which are marked by a more varied relief and rugged topography. Between these lies the old shoreline. The east coast is marked by several lagoons and deltas. The most prominent la- goon is the Chilka Lake on the Orissa coast. It is about 70 km long and its maximum width on the northeast is about 22 km narrowing to some seven kilometers on its southwestern end. It is barred by two spits (a long, narrow sandback extending from the shore) from opposing directions, leaving a narrow opening through which sea water enters into it during high tide. These spits were formed probably by accretion, like some of the islands that occur in the lake. Another remarkable lagoon is the Pulicat, which has been barred by a long sand spit, now known as Sriharikota Island, on which

DIRECTIONDIRECTION Main Examination 13 INSTITUTE FOR IAS EXAMINATION stands the satellite launching station of the Indian Space Research Organization. The lagoon is about 60 km long and about 15 km in the widest part. It is dotted with several large islands, and its northern portion is emerging as a swamp. There are some smaller lagoons on the east coast but many of them now lie far inland having been completely closed by the advancing coastline. The great east-flowing rivers of the Peninsula have formed large deltas. The deltas of the Godavari and the Krishna Rivers have merged with each other, and have advanced their faces towards the sea for at least 30 km during recent years. This is clear from the present position of the Kolleru Lake, which was once a lagoon on the shore but now lies far inland. This lake is now connected with the Goyyeru lagoon by a channel. Some of the smaller east-flowing rivers, like the Subarnarekha, Pennar, Palar and the Coleroon have formed small estuaries. The West Coast The west coast of India also culminates at Kanyakumari. It was also formed due to faulting. This straight-looking coast is however quite jagged marked by a large num- ber of coves (small, sheltered recesses in the coast) and creeks (small tidal inlets or estuaries of small streams). A large number of very small streams descend from the precipitous Sahyadri Range and flow through the narrow coastal plain to open into the ArabianDIRECTION Sea. Although the streams are very small, some of them have formed spec- tacular waterfalls. The Gujarat Plains are built up mainly of the alluvium of the Sabarmati, Mahi, Narmada and the Tapti Rivers, all of which have formed large estuaries. The Konkan Coastal Plain to the south is cliffy and there are several shoals, reefs and islands in the Ara- bian Sea. Bombay was a large island but parts of the sea have been reclaimed in recent years to connect it with the mainland. There is a submerged forest near Bombay which suggests that the sea level rose on the Konkan coast not long ago. This coastal plain is dotted with flat-topped low hills. Transverse, flat-looped spurs come down almost to the shoreline from the edge of the plateau in the northern part of Karnataka; these appear to be abrasional platforms, now dissected by the west-flowing streams. It is only on the Malabar coast that there are seen a number of lakes, lagoons or backwaters which form a noteworthy feature of the coast. These backwaters, locally called kayals, are shallow lagoons or inlets of the sea, lying parallel to the coastline. The largest among these in the Vemband Lake, which is about 75 km long and 5-10 km wide; it gives rise to a 55 km long spit. Cochin harbor is situated on its opening into the sea. These backwaters form an important physical as well as economic feature of the Malabar coast, affording facilities for inland water communication.

DIRECTIONDIRECTION Main Examination 14 INSTITUTE FOR IAS EXAMINATION The silt brought by the recurring monsoon floods supports large forests and planta- tions along their shores. At some places, especially along the tidal estuaries, deltaic fronts, or salt marshes, there are remarkable mangrove swamps lining the coasts. Some unique mud banks have been located between Cochin and Alleppey in the continental shelf off the Vemband Lake. They occur in shallow water, about 10 m deep, and are 25 sq km or more in area. They are possibly the modern analogues of an ancient hydrocarbon generating environment. They are characterized by rapidly accu- mulating fine-grained silty clay, high organic matter, oxygen-deficient bottom waters, and dense mud suspensions. The environment is suitable for gas generation within the sediments. Sea Level Fluctuations The Bay of Bengal and the Arabian Sea came into existence only during the Creta- ceous or early Tertiary period as prolongations of the original ocean after the founder- ing and breakup of Gondwanaland. After that the configuration of the Indian coast more or less assumed the present form, though during the late Pleistocene and early Holocene the shape underwent modifications with fluctuations in the sea level. There is plenty of evidence to show that marine transgressions have taken place since then, some in historical times. TheDIRECTION most well-known example of subsidence or transgression in recent times is the existence of a submerged forest at depths of 6-12 m below the present sea level on the eastern side of the island of Bombay. Marine archaeologists have recently discov- ered the ancient city of Dwarka lying under shallow waters off the coast of Saurashtra. Good examples of eustatic changes of the sea level are provided by the shores of Kathiawar and the Gulf of Kutch. Here, there are raised coral reefs and oyster beds extending inland up to the high level, indicating either that the land has been elevated slightly or the sea level has fallen. Similar littoral concrete of pure reef or calcareous beds of well-cemented shells and corals is also found in many places on the west coast, especially in the city of Bombay. Similar raised oyster beds near Kolkata have also been reported. The Rann of Kutch is the best example of repeated falls in sea level, giving rise to the present day extensive marshland. Striking proofs of the eustatic change are furnished by coastal dunes along the northern edge, islands in the Gulf with typical sea cliffs, sea caves within the plains, and raised beaches of littoral concrete on the fringes of the islands. The total fall in the sea level has been measured at 26 m. Before the Rann became dry, the Luni River used to enter the Arabian Sea through the Kori estuary crossing the entire length of the Great Rann, and the Western Banas flowed over the

DIRECTIONDIRECTION Main Examination 15 INSTITUTE FOR IAS EXAMINATION Little Rann to discharge into the Gulf of Kutch. The Andaman and Nicobar Islands also afford evidence of eustatic rise and fall of the sea level. Raised coral beaches, marine conglomerates and sea caves in uplifted platforms much above the high water mark provide proofs of this. Another evidence of submergence is the existence of drowned valleys of several coastal rivers flowing transverse to the coast. Some islands off the western shore along the Arabian Sea are believed to be mesas and buttes on coastal plains which were isolated to form islands because of submergence of the low-lying areas around them. The land bridge and shallow plat- form of Palk Strait connecting the southern tip of India with Sri Lanka has already been mentioned. Islands India has a number of islands both is Bay of Bengal and Arabian Sea. The Andaman Nicobar islands represent the elevated portions of submarine mountains. The Andaman group incorporates North, Middle, South and little Andamans. Mount Marriet (460 m) is the highest point in the archipelago located in South Andaman. The Nicobar group of islands includes Great Car, little islands Barren and Narcondam are the islands parallel to the main chain and are volcanic in their origin. In Arabian Sea, Amindivi, Cannanoore and Minicoy forms the major group of coral islands. These are collec- tivelyDIRECTION Lakshadweep. These islands have fringing reef very close to their shore. This archipelago forms a north-south trending arcuate chain, convex to the west, and is composed of some 265 islands, from tiny inhospitable rocky projections above the sea level to large islands several hundreds of square kilometers in area. This part of the Bay of Bengal is called the Andaman Sea. The islands cover a cumulative area computed at 8,090 sq km. they stretch from latitude 14° N to 6° 302 N in two distinct groups: the Andaman chain to the north, which is separated by the Ten Degree Chan- nel from the Nicobar group on the south. The distance between the southernmost island in the Andaman chain, the Little Andaman, and the northernmost island of the Nicobar group, the Car Nicobar, is 140 km. The Andaman is a close knit group of 203 islands, covering a total area of 6,496 sq km. The main part, collectively called the Great Andamans – composed of North Andaman, Middle Andaman, South Andaman, Baratang and Rutland Islands along with numerous small islets – forms a compact cluster; it spreads roughly for a length of 260 km and width of 30 km. Separated from it by the Duncan Passage, a 50 km wide open stretch of sea, lies the Little Andaman, about 43 km long and 23 km wide. To the east of the South Andaman, paralleling some 12-25 km away for nearly 600 km, is the Ritchie’s Archipelago.

DIRECTIONDIRECTION Main Examination 16 INSTITUTE FOR IAS EXAMINATION The Nicobar is a group of widely scattered islands, spread over 262 km length and the extreme width of 58 km in the sea, covering a total area of 1,647 sq. km. It is made up of seven large and 12 small islands together with several tiny islets. The Car Nicobar, Teressa, Camorta, Katchall, Nancowry, Little Nicobar and the Great Nicobar are the main islands of this group. The last named is the largest, as the name suggests, 50 km long by 25 km wide. It is the southernmost island of the archipelago, and is only 147 km away from the Indonesian island of Sumatra – the two separated by the Great Channel. Most of the islands in the archipelago are made up of hard rocks, mainly fossiliferous Tertiaries resting on basic and ultra basic volcanics. Some of the islands are fringed with coral reefs, and some coral banks also occur. The topography of these islands is mountainous and rugged, and some of the summits reach consider- able heights. A central range of hills is recognized in the Great Andamans. Some peaks worth mentioning are: the Saddle Peak in North Andaman, 738 m; Mount Diavolo in Middle Andaman, 515 m; Mount Koyob in South Andaman, 460 m; Mount Ford in Rutland Island, 435 m; Mount Deoban in Little Nicobar, 435 m; Mount Thuiller in Great Nicobar, 642 m. The coastal zone of these islands is generally sloping but in some parts cliffs of sandstone and limestone directly overlook the sea. The coasts them- selves are highly indented. The streams are small and swift-flowing. This group of islandsDIRECTION is an assemblage of 25 small islands, the named Lakshadweep, the islands are widely scattered in the Arabian Sea 200-500 km off the coast of Malabar, be- tween the North latitudes of 11° 45 and 8°°. Two subgroups can be recognized. The islands north of the eleventh parallel are collectively known as Amindivi Islands; in- cluded in it are Chetlat, Bitra, Keltan, Kadmat, Amini and a few tiny atolls. The ones south of this parallel are Androth, Pitti, Agatti, Kalpatti, Kavaratti, Cheriyam, Kalpeni, and several small islets designated together as the Cannanoore Islands. Minicoy is an isolated island situated 250 km south of Kavaratti, which is the administrative head- quarters of the Lakshadweep territory. The size of these islands is variable: Bilara, for example, is only a fraction of one sq km. in area; and Minicoy is the largest with an area of 453 sq km. The islands are made up of corals and rise less than five meters above the sea. Their topography is flat with hardly any natural features, like hills or streams, breaking the monotony of their surface. Shallow lagoons occur on the windward (western) side of the islands, while on the eastern seaboard the slopes are steeper. The gradually slop- ing western coral bank, less than one kilometer wide, under shallow sea, ends abruptly from a depth of about 35 m to a precipitous 1,000-1,600 m. Coral sand forms the top surface. A compact crust of fine conglomerate, which appears like a coarse oolitic

DIRECTIONDIRECTION Main Examination 17 INSTITUTE FOR IAS EXAMINATION limestone with embedded shell fragments, occurs under it. These deposits are of Recent to sub-recent age. The age of the dead corals forming the reef is not known with certainty. Most islands in this archipelago have storm beaches consisting of un- consolidated pebbles, shingles, cobbles and boulders on the eastern seaboard. Be- sides, there are some reefs and banks to the north of the Aminidivi group. A cluster of coral atolls between Agatti and Bitra islands is known as Perumulappara. Two clus- ters of atolls northwest of Bitra are the Byramgore Reef and the Cherbaniani or Beleapani Reef. Further north in the Arabian Sea, some 225 to 300 km from the Karnataka coast, lie three large submarine platforms rising from a depth of about 1,500 m to within 100 m of the sea level, known as the Sesostris Bank. This chain consists of continental islands atop the Chagos-Lakshadweep ridge, which is made up of Neogene and Paleogene sediments deposited on a basaltic basement that evidently is an extension of the older part of the Indian shield. The tops of the peaks surmounting the ridge have been built up by corals to form atolls and coral islands. The sediments seem to have been derived from altered basic rocks and may be related to the Deccan Trap volcanic activity. The end of this volcanic activity was followed by subsidence of the ridge to about 2,000 m starting from the Eocene time. After the eruption of the Deccan Trap extensive faulting took place on the western continental margin,DIRECTION resulting in the formation of the Khambhat-Lakshadweep graben. This fault- ing and the subsequent Tertiary uplift of the Western Ghats formed an eastern slope which deprived this graven of large quantities of terrigenous sediments from the Pen- insula and is believed to have resulted in the deposition of biogenic and calcareous sediments till recent times. Continental Margin Feature The whole sea board is surrounded by a submarine ledge: the continental margin, that is, the floor of the ocean which lies between the shoreline and the abyssal or great depths of the ocean floor. This margin is of much greater breadth on the west than on the east. The western margin broadens progressively northwards from the southern tip of the Indian mainland to the Kathiawar Peninsula. From the shelving margin the sea suddenly plunges to depths of more than 1,500 m. The Arabian Sea is much deeper than the Bay of Bengal. The continental shelf, the part of the continental margin which is very gently sloping and lies between the shoreline and the continental slope, generally at 200 m depth, is similarly wider on the west than on the east. While the eastern shelf is more or less free of incongruities, there are a number of shoals, reefs and tiny islands in the Arabian Sea making coastal navigation somewhat hazardous. On the Coromandel Coast the shelf is much narrower. It is certain that the island of Sri

DIRECTIONDIRECTION Main Examination 18 INSTITUTE FOR IAS EXAMINATION Lanka was a part of the southern Indian mainland, severed only in recent times. It is separated by a submerged platform, the Adam’s Bridge, which is barely three metres deep. Outside the Indo-Sri Lanka strait the coastal shelf plunges to 100-2,000 fath- oms. This part of the Indian coast has been invaded by the sea again and again from the Jurassic to mid-Pliocene times, but the broad outlines of the coasts were deter- mined in the Cretaceous. The coastal shelf broadens considerably and shallows to the south of the Ganga delta, because of the heavy alluvium deposits of the Ganga and the Brahmaputra. Beyond the shelf lies the continental slope, which is a part of the continental margin extending up to the continental rise (or oceanic trench) and as a rule has a steeper slope, of 3° – 6°. Where there are ridges and basins between the shorelines and the continental slope and the topography is more complex than that of the slope, this part of the margin is called the continental borderland. The part that is situated between the slope and the abyssal plain (except in areas of oceanic trenches) is known as the continental rise; it has a gentle slope of 1-in-40 to 1-in-2,000, but it may contain sub- marine canyons. The near shore region of the shelf, up to the depth of 15 m, is composed of quartz and heavy mineral sands. Recent terrigenous silts and clays, low in calcium carbonate and highDIRECTION in organic matter, form the floor between 15 and 60 m depths. The outer shelf beyond 60 m and up to 200 m is made up of relict carbonate sands and carbonate rocks as algal and oolitic limestone of Holocene age. On the India-Pakistan continental margin facing the Arabian Sea the fine fraction of the sediments has been separated and deposited on the uppermost part of the conti- nental slope, where recent sedimentation reaches its maximum. Only coarse material has been deposited on the outer shelf; it is rich in oolites, which formed when the sea was at its lowest level at the end of the Pleistocene. Geochemical investigations of the margin sediments have revealed phosphatic con- tent along Kerala, Mangalore and Bombay coasts. Iron, manganese, nickel, cobalt and copper concentrations in the fine-grained sediments of the inner shelf are higher than in the sediments of the outer shelf and the slope. The Eastern Continental Margin This margin is of narrow width, only 30 to 60 km wide between the deltas of the Mahanadi and the Kaveri. Calculations have shows that this shelf is advancing sea- ward at the rate of one kilometer in 25 years because of the sediments brought to it by the great rivers of India. The shelf is a zone of carbonate deposition amid terrigenous muds of the continental slope and the coastal sands and clays. The calcareous matter

DIRECTIONDIRECTION Main Examination 19 INSTITUTE FOR IAS EXAMINATION is mainly in the form of oolites and foraminiferal tests. They were probably formed at a time of lower sea levels during the Pleistocene glaciation. The Western Continental Margin This margin is much broader than that fronting the eastern seaboard of India. From only 40 km on the southern end it gradually widens to almost 330 km south of the Kathiawar Peninsula. A large platform rises on the shelf some 125 km out into the sea fronting the Ratnagiri coast. This bank ascends vertically over 150 m from depths greater than 200 m. Situated south of the Indus Canyon is the Darshak Sea Mount which soars nearly 1,100 m from a depth of about 1,500 m to roughly 450 m below the sea surface. Some other submarine hills have also been charted in this region. These are probably undersea volcanoes related to Deccan Trap activity. The shelf here is floored by three types of sediments gradually passing from one into the other. The near shore zone is of quartz sand (with such heavy minerals as ilmenite and magnetite) extending to a depth of 5-10 m. Clay and silt occur to a depth of 60-70 m, and farther seaward are found calcareous sediments composed of shells, oolites and algae. The inner shelf sediments were contributed by the present-day rivers of the west coast, while the carbonates were deposited during the late Pleistocene when the sea level was much lower than at present. ThereDIRECTION are two important submarine platforms or “banks” on the western continental margin. The bank, some 65 to 250 km west of Bombay, is the Bombay High, which has become famous as a petroleum production field. It consists of several structures spread over an area of roughly 25,000 sq km, and rises steeply within 20-80 km of the sea level from a depth of about 300 m. Paleocene to Miocene sediments sit on top of the basement in this off-shore area. The second, the Angaria Bank, is some 125 km out into the sea fronting the Ratnagiri coast. A small platform here rises very steeply from depths greater than 2,000 m to within 50 m of the sea surface. Submarine Canyons The steep-sides, elongated trenches and valleys, often V-shaped that indent the con- tinental slopes are known as submarine canyons. Oceanographers believe that they are formed by turbidity currents which cut deep troughs in the continental shelf down to the deep sea. Turbidity currents are bottom-flowing streams laden with suspended sediments moving swiftly down subaqueous slopes in bodies of water like lakes and seas; the suspended sediments give them greater density than the surrounding clear water and hence considerable erosive power. According to another view, submarine canyons are formed by faulting and diastrophism. Probably turbidity currents and faulting both play parts in the origin and subsequent deepening of these canyons. Turbidity

DIRECTIONDIRECTION Main Examination 20 INSTITUTE FOR IAS EXAMINATION currents flush down large quantities of sediments along the canyons and accumulate them all along the slope and spread them on the floor of the sea. A well-known canyon off the coast of India is the trench in front of the Ganga delta called the “Swatch of No Ground”. It forms a unique feature of the Bay of Bengal as it notches the continental margin as a narrow, steep-walled depression, at least 150 km long and 12-15 km wide through most of its length but opening out to about 30 km towards its mouth in the Bay. At its head it is only 20-55 m deep but plunges to more than 900 m within a short distance. In general, its bottom is fairly flat. At its head the canyon runs nearly SW but changes direction gradually until some 80 km down it runs nearly south. The earlier view was that the Swatch may have been formed by faulting aided by scouring of the continental margin, but recent oceanographic investigations have shown that it was most probably carved out by turbidity currents. This view is supported by the vast submarine fan that covers the floor of the Bay of Bengal in front of the canyon. The designation “Swatch of No Ground” is also applied to another can- yon in front of the Indus delta, and to avoid confusion between the two, it should more appropriately be called the Ganga Canyon. The Indus Canyon in front of the Indus delta is about 115 km long and 8-10 km wide. At the delta margin its floor is 120 m below the sea level, and at the shelf margin it is 1,130 m deep. It has been traced seawardDIRECTION to a depth of more than 1,800 m, where it appears to end; it has a great fan as a seaward extension. The fan indicates that it may have been scoured by turbidity currents. Both the Swatchs have steep walls and a broad, flat floor instead of the V- shape of the typical submarine canyon. Rock walls or tributaries have not been found in either of them. Oceanographic research in recent years has brought to light several small submarine canyons on the eastern continental margins. Those discovered east-northeast of Vishakhapatnam have been named the Andhra, Mahadevan and Krishnan canyons. They are small and cut into the continental slope. Other such canyons along this coast are the Cuddalore, Puducherry, Palar, Swarnaukhi group, Pennar group, Nagarjuna group, Godavari group, Gautami group, and some others. Most of them are found in the vicinity of the mouths of both major and minor rivers. Their investigations are still at a preliminary stage, and so the exact causes of their origin are not known for certain, but it is surmised that they probably resulted from subaerial erosion by rivers during the Pleistocene and probably much earlier, for the east coast of India acquired its present configuration during the Upper Jurassic time. A canyon cuts through the Precambrian gneisses and quartzite in the shelf off Trincomalee on the east coast of Sri Lanka. It is an extension of the estuary of the

DIRECTIONDIRECTION Main Examination 21 INSTITUTE FOR IAS EXAMINATION Mahaweli River through the Koddiyar Bay. Its walls are precipitous and its average gradient is 7.3° from the vertical, which makes it among the steepest in the world. It was excavated by stream erosion in the geological past and modified thereafter by marine processes. Some other smaller canyons off the straight coast of Sri Lanka have also been surveyed. It may be noted that submarine canyons have been reported only from the east coast of India. No major rivers pour into the sea through the narrow coast in front of the Sahyadri Mountains and thus the sediment transport is inadequate for the generation of turbidity currents in the Arabian Sea. Moreover, the continental margin off the west- ern seaboard is so wide that the feeble currents that may be generated tend to lose their erosive power within very short distances. These factors appear to be respon- sible for the absence of submarine canyons on the continental shelf in front of the west coast of India.

INDIAN DRAINAGE

India is a land of many rivers and mountains. Its geographical area of about 329 MHa is criss-crossed by a large number of small and big rivers, some of them figuring amongstDIRECTION the mighty rivers of the world. The rivers and mountains have a greater significance in the history of Indian cultural development, religious and spiritual life. It may not be an exaggeration to say that the rivers are the heart and soul of Indian life. Inland Water resources of the country are classified as rivers and canals; reservoirs; tanks & ponds; beels, oxbow lakes, derelict water; and brackish water. Other than rivers and canals, total water bodies cover all area of about 7 MHa. Of the fivers and canals, Uttar Pradesh occupies the First place with the total length of rivers and canals as 31.2 thousand km, which is about 17 percent of the total length of rivers and canals in the country. Other states following Uttar Pradesh are Jammu & Kashmir and Madhya Pradesh. Among the remaining forms of the inland water resources, tanks and ponds have maximum area (2.9 MHa.) followed by reservoirs (2.1 MHa.). Most of the area under tanks and ponds lies in Southern States of Andhra Pradesh, Karnataka and Tamil Nadu. These states along with West Bengal, Rajasthan and Uttar Pradesh, ac- count for 62 percent of total area under tanks and ponds in the country. As far as reservoirs are concerned, major states like Andhra Pradesh, Gujarat, Karnataka, Madhya Pradesh, Maharashtra, Orissa, Rajasthan and Uttar Pradesh account for larger portion of area under reservoirs. More than 77 percent of area under beels, oxbow, lakes and derelict water lies in the states of Orissa, Uttar Pradesh and Assam. Orissa

DIRECTIONDIRECTION Main Examination 22 INSTITUTE FOR IAS EXAMINATION ranks first as regards the total area of brackish water and is followed by Gujarat, Kerala and West Bengal. The total area of inland water resources is, thus, unevenly distrib- uted over the country with five states namely Orissa, Andhra Pradesh, Gujarat, Karnataka and West Bengal accounting for more than half of the country’s inland water bodies. Drainage Basin India is blessed with many rivers. Thirteen of them are classified as major rivers whose total catchment area is 252.8 million hectare (MHa). Of the major rivers, the Ganga - Brahmaputra Meghana system is the biggest with catchment area of about 110 M. Ha which is more than 43 percent of the catchment area of all the major rivers in the country. The other major rivers with catchment area more than 10 M.Ha are Indus (32.1 M.Ha.), Godavari (31.3 M.Ha.), Krishna, (25.9 M.Ha.) and Mahanadi (14.2 M.Ha). The catchment area of medium rivers is about 25 M.Ha and Subernarekha with 1.9 M.Ha. catchment area is the largest river among the medium rivers in the country Drainage Basin Represents the areal stretch from where a river system avail its water directly or indirectly. Basin analysis of drainage system therefore represents most prominent geographical avenue of demarcating distinctive typical basin irrespective of their geographical locations. Major River Basin ThirteenDIRECTION major basin have been identified which contribute 85% of total river discharge, Ganges, Indus and Brahmaputra basin characterized with glacial river marks the most prominent that is rest ten associate themselves with near seasonal profile originating either from the central uplands or peninsular, plateau, Sabarmati, Mahi, Narmada, Tapi, Godawari, Krishna, Ravi, Vaigai, Penner, (Brahmani, Baitarni) are included. Medium Basin In total 45 basins are included in this category accounting for 10% of total discharge with prominent that is Luni basin, Chittar, Palar, Rushkuliya and Vamsadhara, Manipur basin, Kaladan basin and Barah basin. Minor basin In total 55 basins contribute 5% of total discharge it includes minor inland drainage along with individual minor river flow. Karakash and Mustag of Jammu and Kashmir, Machhu of Kathiawar and Ghagher of Bhiwani Bagar and other streams Shetrunji, Bhader, Gundlakama, Punneru. The pattern analysis of drainage system that takes into consideration actual flow developed by different rivers of a system to eventually tribute its water to main river. Basic relief feature and associated impact on drainage has been taken up as the geographical base to distinguish the patterns into two broad groups.

DIRECTIONDIRECTION Main Examination 23 INSTITUTE FOR IAS EXAMINATION Antecedent pattern The prominent longitudinal profile and deep gorges associate with the Himalayan drainage of today has been identified in refer to the prevalence of ancient Indo-Brahm (Pascoe) or Shivalik river (Pilgrim). This river is identified to be large geographical river which come in to be as the prominent success or of Himalayan and Tythes Sea. However the flow was identified even with the prior times. The headwater of this river flowed along the Trans Himalayan site of today along the Gulf which extended from present eastern margin of Tibet to Arabian Sea. The flow drainage of this river then was West, North-West and eventual South with mouth associated to the Arabian Sea. Early Tertiary orogenesis and subsequent glyptogenesis facilitated dismembering of Indo-Brahm River into prominent systems, Indus system, Ganges system and Brahmaputra system. The slope modify of the flow is represented the best by the right bank tributary of Ganges, Yamuna. In the initial phase of dismembering Yamuna iden- tified itself as tributary of Indus, drainage in Arabian Sea, approximately up to Oligocene. The prominent orogenesis characterized with early Pliocene changed the course of Yamuna which along with Ghaggar and Luni (inland drainage of today) Saraswati (lost drainage) developed separate system drainage in Gulf of Kuchh. The Pleistocene glyptogenesisDIRECTION South-East turn becoming of tributary of Ganges and leaving behind its tributaries as the inland drainage. The Drainage system of India can be divided into three groups: the great Himalayan rivers of the north, the westward-flowing rivers of central India, and the eastward-flowing rivers of the Deccan Plateau and the rest of peninsular India. Only small portions of India’s rivers are navigable because of silting and the wide seasonal variation in water flow (due to the monsoon climate). Water transport is thus of little importance in India. The Indian subcontinent’s three great northern rivers, the Indus, the Brahmaputra, and the Ganges, flow through India. The Indus, about 2,900kms long, originates in the Himalayas of western Tibet (Sheghee Khabab) flows through the Ladakh region of Jammu and Kashmir state, then enters Pakistan. The waters of three of its tributaries, the Satluj, Ravi and Chenab, have been diverted, under the Indus Water Treaty, for use in India. The Brahmaputra is about 2,900kms long likewise rises in the Tibetan (Yarlong Zangbo) Himalayas. It flows through Assam states and then south through Bangladesh to the Bay of Bengal. The 2,510 km Ganges, known as Ganga in India, rises in the Indian Himalayas and enters the Gangetic plain northeast of Delhi. At Allahabad it is joined by its major tributary, the Yamuna. The main branch of the Ganges flows through Bangladesh to the Bay of Bengal, while a second branch (Hooghly) meets the bay in

DIRECTIONDIRECTION Main Examination 24 INSTITUTE FOR IAS EXAMINATION India, near Kolkata. Both the Brahmaputra and Ganges rivers discharge enormous amounts of water, almost all of it during the monsoon season. These have developed the largest drainage basin of India. Three major rivers flow east into the Bay of Bengal, rising from the western hills of the Deccan Plateau. The northernmost is the Godavari, about 1,400km long. It has a basin (the area drained by a river) one-third the size of the Ganges, and carries one- tenth of the amount of water the Ganges carries. Emptying into the sea not far south of the Godavari is the Krishna (about 1,300km), with a basin equal to the Godavari but carrying only two thirds of the amount of water. The smallest of the three rivers is the Kaveri (760km), with a basin less than one-third the size of the other two rivers. India has a number of other significant rivers. Tributaries of the Ganges from the north include the Kosi, Gandak, Ghaghara, Gomati and Sharda rivers. Joining the Ganges from the south are the Betwa, Chambal, and Son rivers. The Mahi, Sabarmati and Tapi flow west into the Arabian Sea in Gujarat. Flowing west to join the Indus River in Pakistan are the Beas, Chenab, Jhelum, Ravi and Sutlej, all rivers of the Punjab (Hindi for “five rivers”) region of India and Pakistan. The Mahanadi and Brahmani rivers rise in Chhattisgarh and Orissa states, respectively, and flow east to empty into the Bay of Bengal. The waters of all these rivers are used to irrigate crops, but the amountDIRECTION stored for purpose of irrigation and power generation varies enormously from river depending, among other things, on number of dams on the river. The Rivers of India are classified as Himalayan, peninsular, coastal, and inland- drainage basin rivers. Himalayan rivers are snow fed and maintain a high to medium rate of flow throughout the year. The heavy annual average rainfall levels in the Hima- layan catchment areas further add to their rates of flow. During the monsoon months of June to September, the catchment areas are prone to flooding. The volume of the rain- fed peninsular rivers also increases. Coastal streams, especially in the west, are short and episodic. Rivers of the inland system, centered in western Rajasthan state, are few and frequently disappear in years of scant rainfall. The majority of the South Asia’s major rivers flow through broad, shallow valleys and drain into the Bay of Bengal. The Ganga River basin, India’s largest includes approximately 25 percent of the nation’s area; it is bounded by the Himalayas in the north and the Vindhya Range to the south. The Ganga has its source in the glaciers of the Greater Himalayas, which form the frontier between India and Tibet in northwestern Uttar Pradesh. Many Indians believe that the legendary source of the Ganga, and several other important Asian rivers, lies in the sacred Mapam Yumco Lake (known to the Indians as Manasarovar Lake) of western Tibet located approximately 75 kilometers northeast of the India-China-Nepal

DIRECTIONDIRECTION Main Examination 25 INSTITUTE FOR IAS EXAMINATION tri-point. In the northern part of the Ganga River basin, practically all of the tributaries of the Ganga are perennial streams. However, in the southern part, located in the states of Rajasthan and Madhya Pradesh, many of the tributaries are not perennial. Geological Structure The Earth originated about 4.5-4.6 billion years ago. It is characterized by a crust enveloping the interior (mantle) of the planet with a sharp break (Mohorovicic discontinuity) in between. The crust is thickest (30-80 km) in the continental parts of the Earth. The continent represents about 79% of the total volume of the crust. It is not yet precisely known when the continental crust began to form. The oldest in situ conti- nental crust dated in Slave Province of Canada is 3.96 Ga. Scarcity of ancient crust on present Earth’s surface is presumably due mainly to recycling of the old crust into the mantle or due to remelting during the later process of crustal development. The first 50-100 Ma of Earth’s history is characterized by extensive melting in the outer part of the mantle. During this period, a thin komatiitic crust was formed following devolatilization of the mantle. Partial melting of the komatiitic crust produced tonalitic magmas constituting the oldest continental crust. The process of crustal growth incor- porated interaction of early crust with the mantle and redistribution of the crustal con- stituents by sedimentary and tectonic processes involving several evolutionary mecha- nisms.DIRECTION There is a general agreement that bulk of the continental crust was developed during 2.7-3.0 Ga. To sum up, the ancient Earth crust owes its origin to magmatic processes. The oldest recognizable continental crust is composed mainly of tonalitic gneisses containing fragments of komatiite and basalt, part of which belongs to early oceanic crust. An internationally agreeable scheme of time stratigraphic classification of the Precambrian is yet to emerge. According to a broad classification, the period 4.5-4.2 Ga is considered as pre-geological period. The Precambrian era has been provisionally subdivided into three major periods, viz. the Kata-archaean (>3.5 Ga), the Archaean (3.5-2.5 Ga) and the Proterozoic (2.5-0.65 Ga). The Proterozoic has further been divided into Palaeoproterozoic (2.5 to1.6 Ga), Mesoproterozoic (1.6 to 0.8 Ga) and Neoproterozoic (0.8 to 0.65 Ga). The lower and upper limits of these classified periods are not precisely defined. In the late sixties, two distinct tectonic domains were recognized in Precambrian viz. cratons (>2.5 Ga) and encircling mobile belts (< 2.5 Ga). The cratons are mostly Archaean in age and are generally composed of low-grade greenstones and related metasediments (greenschist – am- phibolite facies) with voluminous granitoids belonging to the tonalite-trondhjemite- granodiorite (TTG) suites. Many granite-greenstone terrains of major cratonic blocks show evidence of stratigraphic cyclicity. The deformation in cratonic domains are now

DIRECTIONDIRECTION Main Examination 26 INSTITUTE FOR IAS EXAMINATION recognized to be largely due to extensive granite diapirism. The mobile belts, on the other hand, comprise medium – to high-grade supracrustals, granitoids, gneisses along with a wide array of plutonic suites. The mobile belts generally bear evidence of repeated reactivation and reworking. The stratigraphic relationships in mobile belts are often obliterated due to polyphase tectonothermal events. Framework of Indian Precambrian About two-thirds of the Indian Peninsula comprises Precambrian rocks .These rocks in parts are covered by Phanerozoic sedimentary suites and by the Deccan plateau basalts. The Indo-Gangetic plain occurring between the Precambrian rocks of the Indian Peninsula and the highly deformed suites of the Himalaya conceals northward dipping Precambrian rocks of which little is known. Precambrian rocks of the Himalaya are highly tectonised due to collision of the Indian Peninsula with the Asiatic mainland and are separated from the southern shield by a northward dipping boundary thrust plane. The continuity of Precambrians across this boundary thrust below the Indo-Gangetic alluvium is, therefore, difficult to establish. The Indian Peninsula is traditionally considered to be a monolithic continental shield constituted by crystalline rocks. Later, the Precambrian rocks of India were divided into distinct segments based on principal orogenic trend, viz. Dharwar, Eastern Ghats, AravalliDIRECTION and Satpura. Several genetic classifications have been attempted reflecting divergent interpretation of the tectono-stratigraphic make-up of different parts of the Peninsular shield. There is serious difficulty in adopting a uniform concept-based genetic classification because such concept may change as new data and more ac- ceptable alternate understanding become available at a later date. The subdivisions of the Precambrian rocks of India are not, therefore, strictly based on tectonic status of the different crustal segments either as cratons and mobile belts, or blocks and oro- genic belts, etc. Instead, the (Peninsular) Indian Precambrian crust could be divided into geologically well defined geographical parts. Such geographical parts have been identified taking to consideration that their boundaries, in many cases, are marked by some fundamental crustal dislocations and/ or by vast expanse of Phanerozoic rocks. Two such fundamental crustal dislocation zones in the Indian Precambrian are the Godavari graben and the Mahanadi graben. The portion of the Indian Peninsula lying south and southwest of the Pranhita-Godavari graben can be called the Southern part of the Peninsula. Similarly, another important part lying between Mahanadi graben and the Godavari graben is the Central part of the Peninsula. The combined Eastern and Northeastern part of the Peninsula, north and northeast of the Mahanadi graben with northern boundary formed by the Quaternary landscape of the Indo-Gangetic Plains

DIRECTIONDIRECTION Main Examination 27 INSTITUTE FOR IAS EXAMINATION and the Brahmaputra valley. The North and Northwestern part of the Peninsula lies to north of the tectonic zone between the rocks of the Vindhyan Super group and the Bundelkhand-BGC-Aravalli massif. Each of these parts can conveniently be sub- divided into provinces on the basis of distinct lithological, structural, metamorphic, geochemical characteristics and geochronology. The boundaries of the provinces are usually marked by shear/ fault zone or in some cases by a transition zone. However, genetic terms like craton, mobile belt, cratonic block etc. cannot be entirely avoided because of long usage of these terms in the existing literature Salient characteristics of Precambrian geology of India The Precambrian geology of the geographical segments and the provinces therein can be summarised as follows: Southern part of the Peninsula The region falls south of Central India Tectonic Zone and southwest of the Godavari rift. Only a small part of the Eastern Ghats occupies the northeastern part. The Pre- cambrian rocks of the southern part of the Indian Peninsula are dominantly granulites, high-grade gneisses with migmatites, greenstones, ancient supracrustal rocks, post- tectonic granites and cover sequences viz. Cuddappah, Kurnool, Bhima, Badami, Kaladgi, Pakhal and Sullavai. The southern part of the Peninsula comprises two prov- inces.DIRECTION They are (i) Dharwar Province and (ii) Southern Granulite Province. The Dharwar Province falls north of the Southern Granulite Province and the two are sepa- rated by Palghat-Kavery shear zone. The Dharwar Province is essentially a granite- greenstone terrain characterized by a number of NNW-SSE trending belts of schis- tose rocks separated by granitic terrains. The Province is divisible into western and eastern parts along a major shear zone west of the Closepet Granite. The supracrustal schistose rocks (metavolcanics) belong mostly to Dharwar Super group (3000-2600 Ma), but relics of an earlier supracrustal sequence (Sargur Group; 3400 Ma) have been recognized which predate the granitic gneisses. The tectonometamorphic status of the older and younger schist belts and the gneisses is not very clear. The Southern Granulite Province is made up chiefly of charnockites, mafic granulites and khondalites and is intersected by several shear zones. The province is, however, not solely composed of rocks of granulite facies, but gneisses and supracrustal rocks of amphibolite facies are also abundant. Radiometric dates obtained from this prov- ince vary between 3.0 and 2.0 Ga indicating the ages of the parent rocks, their trans- formation into granulites and also their subsequent retrogression. As a result, this province includes 2.5 Ga old Nilgiri-Madras belts as well as even 550 Ma old charnockites of Madurai and Trivandrum area. This province is often focused in recent

DIRECTIONDIRECTION Main Examination 28 INSTITUTE FOR IAS EXAMINATION literatures in an attempt to reconstruct the East Gondwanaland by a possible Mada- gascar-India fit. Central part of the Peninsula The central part of the Peninsular Shield forms broadly a rectangular area bounded by the Eastern Ghats, the Mahanadi and Godavari rifts, and the Narmada-Son Linea- ment (North). This part is made up dominantly of Archaean to Middle Proterozoic base- ment complexes and Late Proterozoic to Early Palaeozoic platformal cover rocks. The greater part of the area is occupied by granites and gneisses with engulfed and overlying supracrustals of metasedimentary and metavolcanic rocks of Sausar, Sakoli, Bengpal, Bailadila and other suites. In this ancient terrain, a number of Late Protero- zoic basins were developed (e.g. Vindhyan, Indravati, Chhatisgarh, Baster, etc.) which are now occupied by unmetamorphosed sediments. The central part has been broadly divided into three provinces, viz. Bastar Province, Satpura Province and Eastern Ghats Province. The Bastar Province represents major part of the Central Peninsula and includes the rocks of Sukma, Amgaon, Bengpal, Bailadila, Dongargarh and Sakoli belt. Some of the granitoids in the Bastar Province are intrusive into the supracrustal rocks while a number of them appear to form the basement and, thus, are older than the supracrustals. TheDIRECTION oldest granitoid in the Bastar province is a felsic gneiss occurring in Sukma area which is 3.0 Ga old (Pb-Pb age). More recently generated date (U-Pb from single zircon crystals) from the basement (tonalite gneiss) of the Kotri belt indicates an age of 3562 ± 2 Ma. The Satpura Province represents a Proterozoic mobile belt (including Mahakoshal belt, Sausar belt. Bilaspur-Raigarh-Surguja belt and Betul-Chindwara belt) trending ENE-WSW to the west of the Chhattisgarh basin and north of the Amgaon, Sakoli and Nandgaon supracrustals. The rocks in the province are extensively de- formed and metamorphosed during the Early to Middle Proterozoic. Eastern and Northeastern part of the Peninsula This part is separated from the rest of the Indian Peninsula by the Mahanadi rift gra- ben bounding it in the west and south. Different provinces included in this segment are Singhbhum-North Orissa Province, Chhotanagpur Province and Meghalaya Province. The Singhbhum North Orissa Province is characterized by an Archaean continental nucleus (> 3.0 Ga) bounded by the arcuate Singhbhum shear / thrust zone in the north and northwest and Sukinda thrust in the south. This Archaean basement is overlain to the north by Early Proterozoic supracrustals (North Singhbhum Mobile Belt) trending roughly E-W. This belt of supracrustals is bounded by the Chhotanagpur Province, which occurs further towards north. The youngest Precambrian supracrustal sediments

DIRECTIONDIRECTION Main Examination 29 INSTITUTE FOR IAS EXAMINATION in the province occur in the Kolhan basin showing a synclinal structure. Striking char- acteristics of the Singhbhum-North Orissa Province include wide spread occurrences of Early Archaean tonalite-trondhjemite gneiss and greenstone belts with prominent Banded Iron Formation. The Chhotanagpur Province represents a sea of composite granitoids with enclaves of metasedimentary rocks, granulites, subordinate mafic/ ultramafic schists and mi- nor anorthosites. Rocks of the Chhotanagpur belt range in age (K/ Ar dates) from 1500 to 800 Ma. The terrain has experienced a series of tectonothermal events span- ning over more than a billion years. The Meghalaya Province is bounded to the south by the Dawki lineament and its northern edge is covered by alluvium of the Brahmaputra River. The Precambrian rocks of the Khasi Hills representing a part of the province have been subdivided into the Gneissic Complex, non-porphyritic granitic rocks, the supracrustals of the Shillong Group, the Khasi Greenstone and porphyritic plutons. The province is a basement reactivated terrain with a Proterozoic tectonothermal history comparing well with the Chhotanagpur terrain. The Gneissic Complex has yielded two Proterozoic dates viz. 1700 Ma and 1150 Ma with the intrusive porphyritic granite plutons yielding ages around 800 and 550 Ma. NorthDIRECTION and Northwestern part of the Peninsula This part is bounded to the south by the Son-Narmada Tapti mega-lineament. Though the western and northern India is treated together here, these two segments are sepa- rated from each other by a mega thrust/ fault known as the Great Boundary Fault. Provinces identified in this part are Bundelkhand Province, BGC Province and Aravalli- Delhi Province. The Bundelkhand Province is broadly a triangular segment composed of granite-granodiorite, quartzo-feldspathic gneisses and enclaves of metasedimentary and metavolcanic rocks, quartz-reefs and dykes of dolerite. The existing geochrono- logical data indicate that the rocks were cratonised mainly in the Late Archaean pe- riod. The BGC Province is composed of an assemblage (BGC/ Bhilwara Supergroup) of high grade gneisses and granulites, vestiges of greenstones and low grade supracrustals, syn-orogenic granites showing a wide variety of ages (3500 to 2000 Ma) that overlap, the period of deposition of overlying Aravalli-Delhi Supergroup of rocks. The contact between the BGC and the overlying supracrustal suites is a well defined unconformity. Part of the Bhilwara Supergroup appears to represent a conti- nental rift, later developed into an ensimatic orogen. The Aravalli-Delhi province is composed of Proterozoic supracrustal sequences classified as the Aravalli Super- group and the Delhi Supergroup. In addition, a host of granitic, basic and ultrabasic

DIRECTIONDIRECTION Main Examination 30 INSTITUTE FOR IAS EXAMINATION intrusives and acid extrustives of different ages also occur in the Province. Deposition of the Aravalli rocks (dominated by granite derived sediments, carbonates and volcanics) took place in fault-troughs under eugeosynclinal-miogeosynclinal environ- ment. The Delhi basins opened in close proximity to the Aravalli province following the evolution of the Aravalli Supergroup, where thick piles of volcano-sedimentary rocks were deposited. Late Proterozoic igneous and sedimentary rock assemblages (Trans- Aravalli Sequences) grouped under Malani Igneous Suite and Marwar Supergroup respectively, occupy a wide area to the west of the Aravalli Mountains. The Malani and Marwar rocks are not deformed indicating that the episodes of the Precambrian magmatism/ sedimentation in this part of northwestern India are post-tectonic. Tectonics Tectonically the Indian Peninsular Shield is a composite mosaic of several Precam- brian crustal blocks characterized by cratons, mobile belts, terrains of basement re- activation etc. along with cover rocks of Proterozoic and Phanerozoic age and accu- mulated in intracratonic sags and rifts. The joins in between the blocks are mostly thrusts/ rifts, exact nature of which is often uncertain. It seems that most of the evolu- tionary processes took place broadly simultaneously and sequentially in the different blocks. The present day configuration of the Peninsular India took place mainly during the DIRECTIONMiddle Proterozoic period. Deposition of platformal sediments in the sags and rifts was followed by legation of the blocks and it continued from Middle Proterozoic to Early Palaeozoic. The Middle Proterozoic rocks constitute complexly folded mobile belts along the margins of the cratonic blocks. These belts are associated with certain major tectonic elements indicating major zones of dislocation. Some of these disloca- tion surfaces in Indian subcontinent are i) Phulad lineament (suture zone) in north- western India, ii) E-W trending Central Indian Shear in central India, iii) Singhbhum Shear Zone showing a curvilinear trend in eastern India, iv) E-W trending Palghat- Kaveri shear system in south India and v) Mega thrusts (MBT, MCT) showing an aver- age WNW-ESE trend in Extra-peninsular India. Extra-peninsular Region The Extra-peninsular region forms the northern border of the Indian subcontinent and is occupied by the Himalayan mountain range. The Precambrians of the Extra-penin- sular region have been described under two subdivisions viz. i) Eastern Himalaya and ii) Western Himalaya. The segment of the Himalayan belt, which passes through Sikkim, Darjeeling and Arunachal Pradesh, falls in Eastern Himalaya while the Western Himalaya consists rest of the belt. The eastern and western segments broadly show identical geological features.

DIRECTIONDIRECTION Main Examination 31 INSTITUTE FOR IAS EXAMINATION The average trend of the belt in the Eastern Himalaya is E-W while that the western Himalayan is nearly NW-SE. The bulk of the Himalayan range is composed of Prot- erozoic rocks that have undergone thrusting and reactivation during Meso-Cenozoic orogenesis. The Himalayan ranges can be subdivided longitudinally into four regions. These are (from south to north) i) Sub-Himalayas (foothills belt), ii) Lesser (lower) Himalayas, iii) Great (central) Himalayas and iv) Tibetan (Tethyan) Himalayas. The Sub-Himalayas are made up dominantly of Tertiary and Quaternary sediments, which were derived from northern mountains and accumulated along the Main Boundary Thrust bordering the Sub-Himalayas on the north. The Lesser Himalayas consists largely of nappes that override autochthonous Precambrian sedimentary suites. The Great Himalayas override the Lesser Himalayan belt along the Main Central Thrust. It is made up domi- nantly of high grade Precambrian metamorphites overthrust by Phanerozoic rocks. In addition, it contains Cenozoic granites. Multiple deformation and metamorphism, thrust- nappe tectonics, migmatisation and granitic emplacement have made this belt a com- plex tectonic unit. The Tibetan Himalayas are made up of supracrustal assemblage belonging to controversial theories of one-stage Tethys or two-stage Tethys evolution. Though a theory of continental collision is related to the evolution of the Himalayas, the beltDIRECTION bears stamps of geological activities spanning over a period from Early Protero- zoic to the present. According to the plate-tectonic model, the Indian shield was sub- ducted below the overriding Tethyan suite and a sedimentary wedge contained below the two converging plates. It is believed that the Himalayan mountain chain is a part of the global Meso-Cenozoic mobile belt extending from the Atlas-Alpine mountain belts in the west to the Indonesian arc in the east. It is also thought that the northerly advanc- ing Indo-African plate has subducted below the Eurasian plate leaving behind trails of ophiolite sutures. The drifting and legation of India with Eurasia was preceded by rifting of several continental blocks from the northern Indo-Australian margin of the erstwhile Gondwana supercontinent and these tectonic processes took place during a period ranging from Silurian to Cretaceous. Precise classification of the Precam- brian crust in general and that of the Indian shield in particular as adopted and de- scribed in the preceding paragraphs, are based on several important aspects such as major cycles of sedimentation, events of deformation, metamorphism, magmatism etc. during the Precambrian period. In spite of the hindrances in unraveling the history of geological evolution, the present state of knowledge on the subject is at an ad- vanced stage through accumulation of new objective data, revolutionary changes in the understanding of global geological processes and interpretation of earlier and

DIRECTIONDIRECTION Main Examination 32 INSTITUTE FOR IAS EXAMINATION newly generated data which provided a comprehensive picture of this fascinating area of Indian geology. It is, however, needless to mention that the present idea on the scenario is not a complete one since concepts are still evolving with incremental enrichment of knowledge. Mineral Resources Almost all Earth materials are used by humans for something. We require metals for making machines, sands and gravels for making roads and buildings, sand for making computer chips, limestone and gypsum for making concrete, clays for making ceramics, gold, silver, copper and aluminum for making electric circuits, and diamonds and corundum (sapphire, ruby, emerald) for abrasives and jewelry. Mineral resources can be divided into two major categories - Metallic and Nonmetal- lic. Metallic resources are things like Gold, Silver, Tin, Copper, Lead, Zinc, Iron, Nickel, Chromium, and Aluminum. Nonmetallic resources are things like sand, gravel, gypsum, halite, Uranium, dimension stone A mineral resource is a volume of rock enriched in one or more useful materials Finding and exploiting mineral resources requires the application of the principles of geology that you we have discussed or will discuss throughout this course. Some minerals are used as they are found in the ground, i.e. they require no further process- ing DIRECTIONor very little processing. For example - gemstones, sand, gravel, and salt (halite). Most minerals must be processed before they are used. For example: · Iron is the found in abundance in minerals, but the process of extracting iron from different minerals varies in cost depending on the mineral. It is least costly to ex tract the iron from oxide minerals like hematite (Fe2O3), magnetite (Fe3O4), or limonite [Fe(OH)]. Although iron also occurs in olivines, pyroxenes, amphiboles, and biotite, the concentration of iron in these minerals is less, and cost of extrac tion is increased because strong bonds between iron, silicon, and oxygen must be broken. · Aluminum is the third most abundant mineral in the Earth’s crust. It occurs in the most common minerals of the crust - the feldspars (NaAlSi3O8, KalSi3O8, & CaAl2Si2O8, but the cost of extracting the Aluminum from these minerals is high. Thus, deposits containing the mineral gibbsite [Al(OH)3], are usually sought. This explains why recycling of Aluminum cans is cost effective, since the Aluminum in the cans does not have to be separated from oxygen or silicon. Because such things as extraction costs, labor costs, and energy costs vary with time and from country to country, what constitutes an economically viable deposit of miner- als varies considerably in time and place. In general, the higher the concentration of

DIRECTIONDIRECTION Main Examination 33 INSTITUTE FOR IAS EXAMINATION the substance, the more economical it is to mine. Thus we define an ore as a body of material from which one or more valuable substances can be extracted economically. An ore deposit will consist of ore minerals that contain the valuable substance. Gangue minerals are minerals that occur in the deposit but do not contain the valuable substance. Since economics is what controls the grade or concentration of the substance in a deposit that makes the deposit profitable to mine, different substances require differ- ent concentrations to be profitable. But, the concentration that can be economically mined changes due to economic conditions such as demand for the substance and the cost of extraction. For every substance we can determine the concentration necessary in a mineral deposit for profitable mining. By dividing this economical concentration by the aver- age crustal abundance for that substance, we can determine a value called the concentration factor. Origin of Mineral Resources Mineral deposits can be classified on the basis of the mechanism responsible for concentrating the valuable substance. · Magmatic Ore Deposits - substances are concentrated within a body of igneous rockDIRECTION by magmatic processes like crystal fractionation and crystal settling. Magmatic process such as partial melting, crystal fractionation, or crystal settling in a magma chamber can concentrate ore minerals containing valuable substances by taking elements that were once widely dispersed in low concentrations in the magma and concentrating them in minerals that separate from the magma. Examples: o Pegmatites - During fractional crystallization water and elements that do not enter the minerals separated from the magma by crystallization will end up as the last residue of the original magma. This residue is rich in silica and water along with elements like the Rare Earth Elements (many of which are important for making phosphors in color television picture tubes), Lithium, Tantalum, Niobium, Boron, Beryllium, Gold, and Uranium. This residue is often injected into fractures surround ing the igneous intrusion and crystallizes as a rock called a pegmatite that charac teristically consists of large crystals. o Crystal Settling. As minerals crystallize from a magma body, heavy minerals may sink to the bottom of the magma chamber. Such heavy minerals as chromite, olivine, and ilmenite contain high concentrations of Chromium, Titanium, Platinum,

DIRECTIONDIRECTION Main Examination 34 INSTITUTE FOR IAS EXAMINATION Nickel, and Iron. These elements thus attain higher concentrations in the layers that form on the bottom of the magma chamber. · Hydrothermal Ore Deposits - Concentration by hot aqueous (water-rich) fluids flowing through fractures and pore spaces in rocks. Hydrothermal deposits are produced when groundwater circulates to depth and heats up either by coming near a hot igneous body at depth or by circulating to great depth along the geothermal gradient. Such hot water can dissolve valuable substances throughout a large volume of rock. As the hot water moves into cooler areas of the crust, the dissolved substances are precipitated from the hot water solution. If the cooling takes place rapidly, such as might occur in open fractures or upon reaching a body of cool surface water, then precipitation will take place over a limited area, re- sulting in a concentration of the substance attaining a higher value than was originally present in the rocks through which the water passed. Examples: o Massive sulfide deposits at oceanic spreading centers. Hot fluids circulating above the magma chambers at oceanic ridges can scavenge elements like Sulfur, Copper, and Zinc from the rocks through which they pass. As these hot fluids migrate back toward the seafloor, they come in contact with cold groundwater or seaDIRECTION water and suddenly precipitate these metals as sulfide minerals like sphalerite (zinc sulfide) and chalcopyrite (Copper, Iron sulfide). o Vein deposits surrounding igneous intrusions. Hot water circulating around igneous intrusions scavenges metals and silica from both the intrusions and the surrounding rock. When these fluids are injected into open fractures, they cool rapidly and precipitate mainly quartz, but also a variety of sulfide minerals, and sometimes gold, and silver within the veins of quartz. Rich deposits of copper, zinc, lead, gold, silver, tin, mercury, and molybdenum result. Stratabound ore deposits in lake or oceanic sediments. When hot groundwater containing valuable metals scavenged along their flow paths enters unconsolidated sediments on the bottom of a lake or ocean, it may precipitate ore minerals in the pore spaces between grains in the sediment. Such minerals may contain high concentra- tions of lead, zinc, and copper, usually in sulfide minerals like galena (lead sulfide), sphalerite (zinc sulfide), and chalcopyrite (copper-iron sulfide). Since they are included within the sedimentary strata they are called stratabound mineral deposits. · Sedimentary Ore Deposits - substances are concentrated by chemical precipitation from lake or sea water.

DIRECTIONDIRECTION Main Examination 35 INSTITUTE FOR IAS EXAMINATION Although classic sedimentary processes can form mineral deposits, the term sedi- mentary mineral deposit is restricted to chemical sedimentation, where minerals con- taining valuable substances are precipitated directly out of water. Examples: o Evaporite Deposits - Evaporation of lake water or sea water results in the loss of water and thus concentrates dissolved substances in the remaining water. When the water becomes saturated in such dissolved substance they precipitate from the water. Deposits of halite (table salt), gypsum (used in plaster and wall board), borax (used in soap), and sylvite (potassium chloride, from which potassium is extracted to use in fertilizers) result from this process. Iron Formations - These deposits are of iron rich chart and a number of other iron bearing minerals that were deposited in basins within continental crust during the Pro- terozoic (2 billion years or older). They appear to be evaporite type deposits, but if so, the composition of sea water must have been drastically different than it is today. · Placer Ore Deposits - substances are concentrated by flowing surface waters either in streams or along coastlines. The velocity of flowing water determines whether minerals are carried in suspension or deposited. When the velocity of the water slows, large minerals or minerals with a higherDIRECTION density are deposited. Heavy minerals like gold, diamond, and magnetite of the same size as a low density mineral like quartz will be deposited at a higher velocity than the quartz, thus the heavy minerals will be concentrated in areas where water current velocity is low. Mineral deposits formed in this way are called placer deposits. They occur in any area where current velocity is low, such as in point bar deposits, between ripple marks, behind submerged bars, or in holes on the bottom of a stream. The California gold rush in 1849 began when someone discovered rich placer depos- its of gold in streams draining the Sierra Nevada Mountains. The gold originally formed in hydrothermal veins, but it was eroded out of the veins and carried in streams where it was deposited in placer deposits. · Residual Ore Deposits - substances are concentrated by chemical weathering processes. During chemical weathering and original body of rock is greatly reduced in volume by the process of leaching, which removes ions from the original rock. Elements that are not leached form the rock thus occur in higher concentration in the residual rock. The most important ore of Aluminum, bauxite, forms in tropical climates where high tem- peratures and high water throughput during chemical weathering produces highly leached lateritic soils rich in both iron and aluminum. Most bauxite deposits are rela-

DIRECTIONDIRECTION Main Examination 36 INSTITUTE FOR IAS EXAMINATION tively young because they form near the surface of the Earth and are easily removed by erosion acting over long periods of time. In addition, an existing mineral deposit can be turned in to a more highly concentrated mineral deposit by weathering in a process called secondary enrichment. Distribution of Minerals Most of the metallic minerals in India occur in the peninsular plateau region in the old crystalline rocks. Over 97 per cent of coal reserves occur in the valleys of Damodar, Sone, Mahanadi and Godavari. Petroleum reserves are located in the sedimentary basins of Assam, Gujarat and Mumbai High i.e. off-shore region in the Arabian Sea. New reserves have been located in the Krishna-Godavari and Kaveri basins. Most of the major mineral resources occur to the east of a line linking Mangalore and Kanpur. Minerals are generally concentrated in three broad belts in India. There may be some sporadic occurrences here and there in isolated pockets. These belts are : The North-Eastern Plateau Region The South –Western Plateau The North-Western Region

Offshore Mineral wealth of India: TheDIRECTION beach sands of the East and the West coasts of India, particularly, off some parts of Kerala, Tamil Nadu, Andhra Pradesh and Orissa are rich in Monazite, Ilmetite, Zirocon etc. Two giant oil fields, the Bombay high and basin with more than 500 million barrels (50 million tonnes) of recoverable crude oil in each, were discovered in the shallow waters of the Arabian Sea, off the coast of Maharashtra. Polymetallic nodules, rich in some metals (e.g. copper, cobalt, nickel, manganese) located on the deep sea floor in some parts of the Indian Ocean (e.g. Central Indian Ocean basin), are being explored by Indian Institute of Oceanography, Goa. Ferrous Mineral Ferrous minerals such as iron ore, manganese, chromite, etc., provide a strong base for the development of metallurgical industries. Our country is well-placed in respect of ferrous minerals both in reserves and production Iron Ore About 95 per cent of total reserves of iron ore is located in the States of Orissa, Jharkhand, Chhattisgarh, Karnataka, Goa, Andhra Pradesh and Tamil Nadu. In Orissa, iron ore occurs in a series of hill ranges in Sundergarh, Mayurbhanj and Jhar. The important mines are Gurumahisani, Sulaipet, Badampahar (Mayurbhaj), Kiruburu (Kendujhar) and Bonai (Sundergarh). Similar hill ranges, Jharkhand has some of the

DIRECTIONDIRECTION Main Examination 37 INSTITUTE FOR IAS EXAMINATION oldest iron ore mines and most of the iron and steel plants are located around them. Most of the important mines such as Noamundi and Gua are located in Poorbi and Pashchimi Singhbhum districts. This belt further extends to Durg, Dantewara and Bailadila. Dalli, and Rajhara in Durg are the important mines of iron ore in the country. In Karnataka, iron ore deposits occur in Sandur-Hospet area of Bellary district, Baba Budan hills and Kudremukh in Chikmagalur district and parts of Shimoga, Chitradurg and Tumkur districts. The districts of Chandrapur, Bhandara and Ratnagiri in Maharashtra, Karimnagar, Warangal, Kurnool, Cuddapah and Anantapur districts of Andhra Pradesh, Salem and Nilgiris districts of Tamil Nadu are other iron mining regions. Goa has also emerged as an important producer of iron ore. Manganese Manganese is an important raw material for smelting of iron ore and also used for manufacturing ferro alloys. Manganese deposits are found in almost all geological formations, however, it is mainly associated with Dharwar system. Orissa is the lead- ing producer of Manganese. Major mines in Orissa are located in the central part of the iron ore belt of India, particularly in Bonai, Kendujhar, Sundergarh, Gangpur, Koraput, Kalahandi and Bolangir. Karnataka is another major producer and here the mines are located in Dharwar, Bellary, Belgaum, North Canara, Chikmagalur, Shimoga, Chitradurg andDIRECTION Tumkur. Maharashtra is also an important producer of manganese which is mined in Nagpur, Bhandara and Ratnagiri districts. The disadvantage to these mines is that they are located far from steel plants. The manganese belt of Madhya Pradesh ex- tends in a belt in Balaghat-Chhindwara-Nimar-Mandla and Jhabua districts. Non-Ferrous Minerals India is poorly endowed with non-ferrous metallic minerals except bauxite. Bauxite Bauxite is the ore which is used in manufacturing of aluminium. Bauxite is found mainly in tertiary deposits and is associated with laterite rocks occurring extensively either on the plateau or hill ranges of peninsular India and also in the coastal tracts of the country. Orissa happens to be the largest producer of Bauxite. Kalahandi and Sambalpur are the leading producers. The other two areas which have been increas- ing their production are Bolangir and Koraput. The patlands of Jharkhand in Lohardaga have rich deposits. Gujarat, Chhattisgarh, Madhya Pradesh and Maharashtra are other major producers. Bhavanagar, Jamnagar in Gujarat have the major deposits. Chhattisgarh has bauxite deposits in Amarkantak plateau while Katni-Jabalpur area and Balaghat in M.P. have important deposits of bauxite. Kolaba, Thane, Ratnagiri, Satara, Pune and Kolhapur in Maharashtra are important producers

DIRECTIONDIRECTION Main Examination 38 INSTITUTE FOR IAS EXAMINATION Copper Copper is an indispensable metal in the electrical industry for making wires, electric motors, transformers and generators. It is alloyable, malleable and ductile. It is also mixed with gold to provide strength to jewellery. The Copper deposits mainly occur in Singhbhum district in Jharkhand, Balaghat district in Madhya Pradesh and Jhunjhunu and Alwar districts in Rajasthan. Minor producers of Copper are Agnigundala in Guntur District (Andhra Pradesh), Chitradurg and Hasan districts (Karnataka) and South Arcot district (Tamil Nadu). Among the global producers Non-metallic Minerals Among the non-metallic minerals produced in India, mica is the important one. The other minerals extracted for local consumption are limestone, dolomite and phosphate. Mica Mica is mainly used in the electrical and electronic industries. It can be split into very thin sheets which are tough and flexible. Mica in India is produced in Jharkhand, Andhra Pradesh and Rajasthan followed by Tamil Nadu, West Bengal and Madhya Pradesh. In Jharkhand high quality mica is obtained in a belt extending over a distance of about 150 km, in length and about 22 km, in width in lower Hazaribagh plateau. In Andhra Pradesh,DIRECTION Nellore district produces the best quality mica. In Rajasthan mica belt is in Jaipur, Bhilwara and Udaipur

EARTHQUAKE HAZARDS IN INDIA

India has had a long history of earthquake occurrences. About 65% of the total area of the country is vulnerable to seismic damage of buildings in varying degrees. The most vulnerable areas, according to the present seismic zone map of India, are located in the Himalayan and sub-Himalayan regions, Kutch and the Andaman and Nicobar Is- lands. Depending on varying degrees of seism city, the entire country can be divided into the following seismic regions: · Kashmir and Western Himalayas - Covers the states of Jammu and Kashmir, Himachal Pradesh and sub-mountainous areas of Punjab · Central Himalayas - Includes the mountain and sub-mountain regions of Uttar Pradesh and the sub-mountainous parts of Punjab · North-east India - Comprises the whole of Indian territory to the east of north Bengal

DIRECTIONDIRECTION Main Examination 39 INSTITUTE FOR IAS EXAMINATION · Indo-Gangetic basin and Rajasthan - This region comprises of Rajasthan, plains of Punjab, Haryana, Uttar Pradesh and West Bengal · Cambay and Rann of Kutch · Peninsular India, including the islands of Lakshwadeep · The Andaman and Nicobar Islands Seismic Zoning of India Bureau of Indian Standards based on various scientific inputs from a number of agen- cies including earthquake data supplied by IMD, has grouped the country into four seismic zones viz., Zone-II, -III, -IV and -V. Of these, zone V is rated as the most seismically prone region, while zone II is the least. The Modified Mercalli (MM) inten- sity, which measures the impact of the earthquakes on the surface of the earth, broadly associated with various zones, is as follows:

Seismic Zone Intensity on MMI scale % of total area II (Low intensity zone) VI (or less) 43% III (Moderate intensity zone) VII 27% IV (Severe intensity zone) VIII 18% V (VeryDIRECTION severe intensity zone) IX (and above) 12%

PRE-DISASTER PREVENTIVE MEASURES

Long-term measures · Re-framing buildings’ codes, guidelines, manuals and byelaws and their strict imple mentation. Tougher legislation for highly seismic areas. · Incorporating earthquake resistant features in all buildings at high-risk areas. · Making all public utilities like water supply systems, communication networks, elec tricity lines etc. earthquake-proof. Creating alternative arrangements to reduce dam ages to infrastructure facilities. · Constructing earthquake-resistant community buildings and buildings (used to gather large groups during or after an earthquake) like schools, dharamshalas, hospitals, prayer halls, etc., especially in seismic zones of moderate to higher intensities. · Supporting R&D in various aspects of disaster mitigation, preparedness and prevention and post-disaster management.

DIRECTIONDIRECTION Main Examination 40 INSTITUTE FOR IAS EXAMINATION · Evolving educational curricula in architecture and engineering institutions and tech nical training in polytechnics and schools to include disaster related topics. Medium term measures · Retrofitting of weak structures in highly seismic zones. · Preparation of disaster related literature in local languages with dos and don’ts for construction. · Getting communities involved in the process of disaster mitigation through educa tion and awareness. · Networking of local NGOs working in the area of disaster management Earthquake monitoring India Meteorological Department (IMD) is the nodal agency of Government of India responsible for monitoring seismic activity in and around the country. IMD has ren- dered more than a century of seismological service to the nation with the first seismo- logical observatory of the country having been set up by the department at Kolkata in 1898. The operational task of the department is to quickly estimate the earthquake source parameters immediately on occurrence of an earthquake and disseminate the information to all the user agencies including the concerned State and Central Gov- ernment agencies responsible for carrying out relief and rehabilitation measures. The informationDIRECTION relating to under-sea earthquakes capable of generating tsunamis on the Indian coastal regions is also disseminated to all concerned user agencies including the Indian National Centre for Ocean Information Services (INCOIS), Hyderabad for issue of tsunami related messages and warnings. The earthquake information is trans- mitted to various user agencies including public information channels, press, media etc. National Seismological Network (NSN) India Meteorological Department is maintaining a country wide National Seismologi- cal Network (NSN), consisting of a total of 82 seismological stations, spread over the entire length and breadth of the country. This includes: a) 16-station V-SAT based digital seismic telemetry system around National Capital Territory (NCT) of Delhi, b) 20- station VSAT based real time seismic monitoring network in North East region of the country and (c) 17-station Real Time Seismic Monitoring Network (RTSMN) to monitor and report large magnitude under-sea earthquakes capable of generating tsunamis on the Indian coastal regions. The remaining stations are of standalone/ analog type. A Control Room is in operation, on a 24X7 basis, at IMD Headquarters (Seismology) in New Delhi, with state-of-the art facilities for data collection, process- ing and dissemination of information to the concerned user agencies.

DIRECTIONDIRECTION Main Examination 41 INSTITUTE FOR IAS EXAMINATION Real time seismic monitoring for early warning of tsunamis In the aftermath of the Great Sumatra earthquake of 26th December, 2004, Ministry of Earth Sciences has set up an Indian Tsunami Early Warning Center at the Indian Na- tional Centre for Ocean Information Services (INCOIS), Hyderabad. The Center is mandated to provide advance warnings on Tsunamis likely to affect the coastal areas of the country. As part of this, a 17-station Real Time Seismic Monitoring Network (RTSMN) has been set up by India Meteorological Department. The network is ca- pable of monitoring and reporting, in least possible time, the occurrence of earth- quakes capable of generating Tsunamis likely to affect the Indian coastal regions. The data from the 17 Broadband seismic field stations is transmitted simultaneously in real time through V-SAT communication facilities to the Central Receiving Stations (CRSs) located at IMD, New Delhi and INCOIS, Hyderabad for processing and inter- pretation. The CRSs are equipped with state-of-art computing hardware, communi- cation, data processing, visualization and dissemination facilities. For providing bet- ter azimuthal coverage towards detecting earthquakes of tsunami-genic potential, the RTSMN system has been configured to include about 100 global stations of IRIS (a consortium of Incorporated Research Institutions in Seismology), whose data is avail- able freely through internet. The earthquake information is disseminated through vari- ousDIRECTION communication channels to all the concerned user agencies in a fully automated mode. Based on the earthquake information provided by the RTSMN and other ocean related observations / analysis, INCOIS evaluates the tsunamigenic potential of the undersea earthquakes and issues necessary warnings / alerts, as per the situation.

CLIMATE The monsoon regime emphasizes the unity of India with the rest of Southeast Asian region. The climate of Kerala and Tamil Nadu in the south are so different from that of Uttar Pradesh and Bihar in the north, and yet all of these have a monsoon type of climate. The climate of India has many regional variations expressed in the pattern of winds, temperature and rainfall, rhythm of seasons and the degree of wetness or dryness. While in the summer the mercury occasionally touches 55°C in the western Rajasthan, it drops down to as low as minus 45°C in winter around Leh. Churu in Rajasthan may record a temperature of 50°C or more on a June day while the mercury hardly touches 19°C in Tawang (Arunachal Pradesh) on the same day. On a December night, temperature in Drass (Jammu and Kashmir) may drop down to minus 45°C while Thiruvananthapuram or Chennai on the same night records 20°C or 22°C. These examples confirm that there are seasonal

DIRECTIONDIRECTION Main Examination 42 INSTITUTE FOR IAS EXAMINATION variations in temperature from place to place and from region to region in India. While snowfall occurs in the Himalayas, it only rains over the rest of the country. Similarly, variations are noticeable not only in the type of precipitation but also in its amount. While Cherrapunji and Mawsynram in the Khasi Hills of Meghalaya receive rainfall over 1,080 cm in a year, Jaisalmer in Rajasthan rarely gets more than 9 cm of rainfall during the same period. Tura situated in the Garo Hills of Meghalaya may receive an amount of rainfall in a single day which is equal to 10 years of rainfall at Jaisalmer. While the annual precipitation is less than 10 cm in the north-west Himalayas and the western deserts, it exceeds 400 cm in Meghalaya. The Ganga delta and the coastal plains of Orissa are hit by strong rain-bearing storms almost every third or fifth day in July and August while the Coromandal coast, a thousand km to the south, goes generally dry during these months. Most parts of the country get rainfall during June-September, but on the coastal areas of Tamil Nadu, it rains in the beginning of the winter season. In spite of these differences and variations, the climate of India is monsoonal in rhythm and character. FACTORSDIRECTION DETERMINING THE CLIMATE OF INDIA India’s climate is controlled by a number of factors which can be broadly divided into two groups — factors related to location and relief, and factors related to air pressure and winds.

Latitude: Northern part of the India lies in sub-tropical and temperate zone and the part lying south of the Tropic of Cancer falls in the tropical zone. The tropical zone, being nearer to the equator, experiences high temperatures throughout the year with small daily and annual range of temperature. The area north of the Tropic of Cancer which is away from the equator, experiences extreme climate with high daily and annual range of temperature. The Himalayan Mountains: The lofty Himalayas in the north along with its extensions act as an effective climatic divide. The towering mountain chain provides an invincible shield to protect the subcontinent from the cold northern winds. These cold and chilly winds originate near the Arctic circle and blow across central and eastern Asia. The Himalayas also trap the monsoon winds, forcing them to shed their moisture within the subcontinent.

DIRECTIONDIRECTION Main Examination 43 INSTITUTE FOR IAS EXAMINATION Distribution of Land and Water: India is flanked by the Indian Ocean on three sides in the south and girdled by a high and continuous mountain-wall in the north. As compared to the landmass, water heats up or cools down slowly creating different air pressure zones in different seasons in and around the Indian subcontinent. Difference in air pressure causes reversal in the direction of monsoon winds. Distance from the Sea: With a long coastline, large coastal areas have an equable climate. Areas in the interior of India are far away from the moderating influence of the sea. The seasonal contrasts in weather at places in the interior of the country such as Delhi, Kanpur and Amritsar affect the entire sphere of life. Altitude : Temperature decreases with height. Due to thin air, places in the mountains are cooler than places on the plains. For example, Agra and Darjeeling are located on the same latitude, but temperature of January in Agra is 16°C whereas it is only 4°C in Darjeeling. Relief : The physiography or relief of India also affects the temperature, air pressure, direction and speed of wind and the amount and distribution of rainfall. The windward sides of Western Ghats and Assam receive high rainfall during June-September whereas the southern plateau remains dry due to its leeward situation along the WesternDIRECTION Ghats. To understand the differences in local climates of India, we need to understand the mechanism of the following three factors: (i) Distribution of air pressure and winds on the surface of the earth. (ii) Upper air circulation caused by factors controlling global weather and the inflow of different air masses and jet streams. (iii) Inflow of western cyclones generally known as disturbances during the winter season and tropical depressions during the south-west monsoon period into India, creating weather conditions favourable to rainfall. The mechanism of these three factors can be understood with reference to winter and summer seasons of the year separately. Mechanism of Weather in the Winter Season In winter months, the weather conditions over India are generally influenced by the distribution of pressure in Central and Western Asia. A high pressure centre in the region lying to the north of the Himalayas develops during winter giving rise to the flow of air at the low level from the north towards the Indian subcontinent, south of the mountain range. The surface winds

DIRECTIONDIRECTION Main Examination 44 INSTITUTE FOR IAS EXAMINATION blowing out of the high pressure centre over Central Asia reach India in the form of a dry continental air mass and come in contact with trade winds over northwestern India. The position of this contact zone is not, however, stable but occasionally shift its position as far east as the middle Ganga valley with the result that the whole of the northwestern and northern India up to the middle Ganga valley comes under the influence of dry northwestern winds. Jet Stream and Upper Air Circulation: The variations in the atmospheric pressure closer to the surface of the earth have no role to play in the making of upper air circulation. All of Western and Central Asia remains under the influence of westerly winds along the altitude of 9-13 km from west to east that blow across the Asian continent at latitudes north of the Himalayas roughly parallel to the Tibetan highlands. These are known as jet streams. Tibetan highlands act as a barrier in the path of these jet streams resulting in bifurcation of jet streams. One of its branches blows to the north of the Tibetan highlands, while the southern branch blows in an eastward direction, south of the Himalayas. Western Cyclonic Disturbance and Tropical Cyclone: The western cyclonic disturbances which enter the Indian subcontinent from the west and the northwest duringDIRECTION the winter months, originate over the Mediterranean Sea and are brought into India by the westerly jet stream. An increase in the prevailing night temperature generally indicates an advance in the arrival of these cyclones disturbances. Tropical cyclones originate over the Bay of Bengal and the Indian ocean and with a high wind velocity and heavy rainfall, hit the Tamil Nadu, Andhra Pradesh and Orissa coast. Most of these cyclones are very destructive due to high wind velocity and torrential rain that accompanies it. Mechanism of Weather in the Summer Season As the summer sets in and the sun shifts northwards, the wind circulation over the subcontinent undergoes a complete reversal at both, the lower as well as the upper levels. By the middle of July, the low pressure belt nearer the surface [termed as Inter Tropical Convergence Zone (ITCZ)] shifts northwards, roughly parallel to the Himalayas between 20° N and 25° N. By this time, the westerly jet stream withdraws from the Indian region. The ITCZ being a zone of low pressure, attracts inflow of winds from different directions. The maritime tropical air mass (mT) from the southern hemisphere, after crossing the equator, rushes to the low pressure area in the general southwesterly direction. It is this moist air current which is popularly known as the southwest monsoon.

DIRECTIONDIRECTION Main Examination 45 INSTITUTE FOR IAS EXAMINATION Jet Streams and Upper Air Circulation: An easterly jet stream flows over the southern part of the Peninsula in June, and has a maximum speed of 90 km per hour. In August, it is confined to 15oN latitude, and in September up to 22o N latitudes. The easterlies normally do not extend to the north of 30o N latitude in the upper atmosphere. Easterly Jet Stream and Tropical Cyclones: The easterly jet stream steers the tropical depressions into India that play a significant role in the distribution of monsoon rainfall over the Indian subcontinent. The tracks of these depressions are the areas of highest rainfall in India and the frequency at which these depressions visit India, their direction and intensity, all go a long way in determining the rainfall pattern during the southwest monsoon period.

INDIAN MONSOON Monsoon is a familiar though a little known climatic phenomenon. Many attempts have been made to discover the exact nature and causation of monsoon, but so far, no single theory has been able to explain the monsoon fully. Systematic studies of the causes of rainfall in the South Asian region help to understand the causes and salient features of the monsoon, particularly some of its important aspects, suchDIRECTION as: The onset of the monsoon ,Rain-bearing systems (e.g. tropical cyclones) and the relationship between their frequency and distribution of monsoon rainfall. and Break in the monsoon. Onset of the Monsoon During April and May when the sun shines vertically over the Tropic of Cancer, the large landmass in the north of Indian ocean gets intensely heated. This causes the formation of an intense low pressure in the northwestern part of the subcontinent. Since the pressure in the Indian Ocean in the south of the landmass is high as water gets heated slowly, the low pressure cell attracts the southeast trades across the Equator. These conditions help in the northward shift in the position of the ITCZ. The shift in the position of the ITCZ is also related to the phenomenon of the withdrawal of the westerly jet stream from its position over the north Indian plain, south of the Himalayas. The easterly jet stream sets in along 15°N latitude only after the western jet stream has withdrawn itself from the region. This easterly jet stream is held responsible for the burst of the monsoon in India. Entry of Monsoon into India : The southwest monsoon sets in over the Kerala coast by 1st June and moves swiftly to reach Mumbai and Kolkata between 10th and 13th June. By mid-July, southwest monsoon engulfs the entire subcontinent.

DIRECTIONDIRECTION Main Examination 46 INSTITUTE FOR IAS EXAMINATION Rain-bearing Systems and Rainfall Distribution There seem to be two rain- bearing systems in India. The first one originates in the Bay of Bengal causing rainfall over the plains of north India and the second is the Arabian Sea current of the south-west monsoon which brings rain to the west coast of India. Much of the rainfall along the Western Ghats is orographic as the moist air is obstructed and forced to rise along the Ghats. The intensity of rainfall over the west coast of India is, however, related to two factors: (i) The offshore meteorological conditions. (ii) The position of the equatorial jet stream along the eastern coast of Africa. The frequency of the tropical depressions originating from the Bay of Bengal varies from year to year. Their paths over India are mainly determined by the position of ITCZ which is generally termed as the monsoon trough. As the axis of the monsoon trough oscillates, there are fluctuations in the track and direction of these depressions, and the intensity and the amount of rainfall vary from year to year. The rain which comes in spells, displays a declining trend from west to east over the west coast, and from the southeast towards the northwest over the North Indian Plain and the northern part of the Peninsula.

BreakDIRECTION in the Monsoon During the south-west monsoon period after having rains for a few days, if rain fails to occur for one or more weeks, it is known as break in the monsoon. These dry spells are quite common during the rainy season. These breaks in the different regions are due to different reasons: (i) In northern India rains are likely to fail if the rain-bearing storms are not very frequent along the monsoon trough or the ITCZ over this region. (ii) Over the west coast the dry spells are associated with days when winds blow parallel to the coast. Season Cycle The climatic conditions of India can best be described in terms of an annual cycle of seasons. The meteorologists recognize the following four seasons: (i) the cold weather season (ii) the hot weather season (iii) the southwest monsoon season (iv)the retreating monsoon season.

DIRECTIONDIRECTION Main Examination 47 INSTITUTE FOR IAS EXAMINATION The Cold Weather Season Usually, the cold weather season sets in by mid- November in northern India. December and January are the coldest months in the northern plain. The mean daily temperature remains below 21°C over most parts of northern India. The night temperature may be quite low, sometimes going below freezing point in Punjab and Rajasthan. There are three main reasons for the excessive cold in north India during this season : (i) States like Punjab, Haryana and Rajasthan being far away from the moderating influence of sea experience continental climate. (ii) The snowfall in the nearby Himalayan ranges creates cold wave situation; and (iii) Around February, the cold winds coming from the Caspian Sea and Turkmenistan bring cold wave along with frost and fog over the northwestern parts of India.

The Peninsular region of India, however, does not have any well-defined cold weather season. There is hardly any seasonal change in the distribution pattern of the temperature in coastal areas because of moderating influence of the sea and the proximity to equator. By the end of December (22nd December), the sun shines vertically over the Tropic of Capricorn in the southern hemisphere. The weatherDIRECTION in this season is characterized by feeble high pressure conditions over the northern plain. In south India, the air pressure is slightly lower. As a result, winds start blowing from northwestern high pressure zone to the low air pressure zone over the Indian Ocean in the south. Due to low pressure gradient, the light winds with a low velocity of about 3-5 km per hour begin to blow outwards. By and large, the topography of the region influences the wind direction. They are westerly or northwesterly down the Ganga Valley. They become northerly in the Ganga- Brahmaputra delta. During the winters, the weather in India is pleasant but gets disturbed by shallow cyclonic depressions originating over the east Mediterranean Sea and travelling eastwards across West Asia, Iran, Afghanistan and Pakistan before they reach the northwestern parts of India. On their way, the moisture content gets augmented from the Caspian Sea in the north and the Persian Gulf in the south. Winter monsoons do not cause rainfall as they move from land to the sea. It is because firstly, they have little humidity; and secondly, due to anti cyclonic circulation on land, the possibility of rainfall from them reduces. So, most parts of India do not have rainfall in the winter season. However, there are some exceptions to it:

DIRECTIONDIRECTION Main Examination 48 INSTITUTE FOR IAS EXAMINATION (i) In northwestern India, some weak temperate cyclones from the Mediterranean sea cause rainfall in Punjab, Haryana, Delhi and western Uttar Pradesh. The precipitation is in the form of snowfall in the lower Himalayas. It is this snow that sustains the flow of water in the Himalayan rivers during the summer months. The precipitation goes on decreasing from west to east in the plains and from north to south in the mountains. The average winter rainfall in Delhi is around 53 mm. In Punjab and Bihar, rainfall remains between 25 mm and 18 mm respectively.

(ii) Central parts of India and northern parts of southern Peninsula also get winter rainfall occasionally.

(iii) Arunachal Pradesh and Assam in the northeastern parts of India also have rains between 25 mm and 50 mm during these winter months.

(iv)During October and November, northeast monsoon while crossing over the Bay of Bengal, picks up moisture and causes torrential rainfall over the Tamil Nadu coast, southern Andhra Pradesh, southeast Karnataka and southeast Kerala.

TheDIRECTION Hot Weather Season With the apparent northward movement of the sun towards the Tropic of Cancer in March, temperatures start rising in north India. In most parts of India, temperatures recorded are between 30°-32°C. In March, the highest day temperature of about 38°C occurs in the Deccan Plateau while in April, temperature ranging between 38°C and 43°C are found in Gujarat and Madhya Pradesh. In May, the heat belt moves further north, and in the north-western part of India, temperatures around 48°C are not uncommon. The hot weather season in south India is mild and not so intense as found in north India. The Peninsular situation of south India with moderating effect of the oceans keeps the temperatures lower than that prevailing in north India. So, temperatures remain between 26°C and 32°C. Due to altitude, the temperatures in the hills of Western Ghats remain below 25°C. In the coastal regions, the north-south extent of isotherms parallel to the coast confirms that temperature does not decrease from north to south rather it increases from the coast to the interior. The mean daily minimum temperature during the summer months also remains quite high and rarely goes below 26°C. The summer months are a period of excessive heat and falling air pressure in the northern half of the

DIRECTIONDIRECTION Main Examination 49 INSTITUTE FOR IAS EXAMINATION country. Because of the heating of the subcontinent, the ITCZ moves northwards occupying a position centered at 25°N in July. The location of the ITCZ attracts a surface circulation of the winds which are southwesterly on the west coast as well as along the coast of West Bengal and Bangladesh. They are easterly or south-easterly over north Bengal and Bihar. In the heart of the ITCZ in the northwest, the dry and hot winds known as ‘Loo’, blow in the afternoon, and very often, they continue to well into midnight. Dust storms in the evening are very common during May in Punjab, Haryana, Eastern Rajasthan and Uttar Pradesh. These temporary storms bring a welcome respite from the oppressing heat since they bring with them light rains and a pleasant cool breeze. Occasionally, the moisture-laden winds are attracted towards the periphery of the trough. A sudden contact between dry and moist air masses gives rise to local storms of great intensity. These local storms are associated with violent winds, torrential rains and even hailstorms. The Advancing Monsoon By early June, they are powerful enough to attract the trade winds of Southern Hemisphere coming from the Indian Ocean. These southeast trade winds cross the equator and enter the Bay of Bengal and the Arabian Sea, only to be caught up inDIRECTION the air circulation over India. Passing over the equatorial warm currents, they bring with them moisture in abundance. After crossing the equator, they follow a southwesterly direction. That is why they are known as southwest monsoons. The rain in the southwest monsoon season begins rather abruptly. One result of the first rain is that it brings down the temperature substantially. This sudden onset of the moisture-laden winds associated with violent thunder and lightening, is often termed as the “break” or “burst” of the monsoons. The monsoon may burst in the first week of June in the coastal areas of Kerala, Karnataka, Goa and Maharashtra while in the interior parts of the country, it may be delayed to the first week of July. The day temperature registers a decline of 5°C to 8°C between mid-June and mid-July. As these winds approach the land, their southwesterly direction is modified by the relief and thermal low pressure over the northwest India. The monsoon approaches the landmass in two branches: (a) The Arabian Sea branch (b) The Bay of Bengal branch. Monsoon Winds of the Arabian Sea The monsoon winds originating over the Arabian Sea further split into three branches: Its one branch is obstructed by the Western Ghats. These winds climb the slopes

DIRECTIONDIRECTION Main Examination 50 INSTITUTE FOR IAS EXAMINATION of the Western Ghats from 900-1200 m and soon becomes cool, and as a result, the windward side of the Sahyadris and Western Coastal Plain receive very heavy rainfall ranging between 250 cm and 400 cm. After crossing the Western Ghats, these winds descend and get heated up reducing humidity in the winds. As a result, these winds cause little rainfall east of the Western Ghats. This region of low rainfall is known as the rain-shadow area. Another branch of the Arabian sea monsoon strikes the coast north of Mumbai. Moving along the Narmada and Tapi river valleys, these winds cause rainfall in extensive areas of central India. The Chotanagpur plateau gets 15 cm rainfall from this part of the branch. Thereafter, they enter the Ganga plains and mingle with the Bay of Bengal branch. A third branch of this monsoon wind strikes the Saurashtra Peninsula and the Kachchh passing over west Rajasthan and along the Aravallis, causing only a scanty rainfall. In Punjab and Haryana, it too joins the Bay of Bengal branch. These two branches, reinforced by each other, cause rains in the western Himalayas. Monsoon Winds of the Bay of Bengal The Bay of Bengal branch strikes the coast of Myanmar and part of southeast Bangladesh. But the Arakan Hills along the coast of Myanmar deflect a big portion of thisDIRECTION branch towards the Indian subcontinent and the monsoon, therefore, enters West Bengal and Bangladesh from south and southeast instead of from the south- westerly direction. From here, this branch splits into two under the influence of the Himalayas and the thermal low is northwest India. Its one branch moves westward along the Ganga plains reaching as far as the Punjab plains. The other branch moves up the Brahmaputra valley in the north and the northeast, causing widespread rains. Its sub-branch strikes the Garo and Khasi hills of Meghalaya. Mawsynram, located on the crest of Khasi hills, receives the highest average annual rainfall in the world. The Tamil Nadu coast remains dry during this season because of the two factors: (i) The Tamil Nadu coast is situated parallel to the Bay of Bengal branch of southwest monsoon. (ii) It lies in the rain shadow area of the Arabian Sea branch of the south-west monsoon.

DIRECTIONDIRECTION Main Examination 51 INSTITUTE FOR IAS EXAMINATION Characteristics of Monsoonal Rainfall Rainfall received from the southwest monsoons is seasonal in character, which occurs between June and September. Monsoonal rainfall is largely governed by relief or topography. For instance the windward side of the Western Ghats register a rainfall of over 250 cm. Again, the heavy rainfall in the northeastern states can be attributed to their hill ranges and the Eastern Himalayas. The monsoon rainfall has a declining trend with increasing distance from the sea. Kolkata receives 119 cm during the southwest monsoon period, Patna 105 cm, Allahabad 76 cm and Delhi 56 cm. The monsoon rains occur in wet spells of few days duration at a time that are interspersed with rainless interval known as ‘breaks’. These breaks in rainfall are related to the cyclonic depressions mainly formed at the head of the Bay of Bengal, and their crossing into the mainland. Besides the frequency and intensity of these depressions, the passage followed by them determines the spatial distribution of rainfall. The summer rainfall comes in a heavy downpour leading to considerable run off and soil erosion. Monsoons play a pivotal role in the agrarian economy of India because over three-fourths of the total rain in the country is received during the south-west monsoon season. Its spatial distribution is alsoDIRECTION uneven which ranges from 12 cm to more than 250 cm. The beginning of the rains sometimes is considerably delayed over the whole or a part of the country. The rains sometimes end considerably earlier than usual, causing great damage to standing crops and making the sowing of winter crops difficult. Season of Retreating Monsoon The months of October and November are known for retreating monsoons. By the end of September, the southwest monsoon becomes weak as the low pressure trough of the Ganga plain starts moving southward in response to the southward march of the sun. The monsoon retreats from the western Rajasthan by the first week of September. By the beginning of October, the low pressure covers northern parts of the Bay of Bengal and by early November, it moves over Karnataka and Tamil Nadu. By the middle of December, the centre of low pressure is completely removed from the Peninsula. The retreating southwest monsoon season is marked by clear skies and rise in temperature. Owing to the conditions of high temperature and humidity, the weather becomes rather oppressive. This is commonly known as the ‘October heat’ .In the second half of October, the mercury begins to fall rapidly, particularly in northern India. The weather in the retreating monsoon is dry in north India but it is associated with rain in the eastern part of the Peninsula.

DIRECTIONDIRECTION Main Examination 52 INSTITUTE FOR IAS EXAMINATION Here, October and November are the rainiest months of the year. The widespread rain in this season is associated with the passage of cyclonic depressions which originate over the Andaman Sea and manage to cross the eastern coast of the southern Peninsula. These tropical cyclones are very destructive. The thickly populated deltas of the Godavari, Krishna and Kaveri are their preferred targets. Every year cyclones bring disaster here. A few cyclonic storms also strike the coast of West Bengal, Bangladesh and Myanmar. A bulk of the rainfall of the Coromondal coast is derived from these depressions and cyclones. Such cyclonic storms are less frequent in the Arabian Sea. Distribution of Rainfall The average annual rainfall in India is about 125 cm, but it has great spatial variations. Areas of High Rainfall : The highest rainfall occurs along the west coast, on the Western Ghats, as well as in the sub-Himalayan areas is the northeast and the hills of Meghalaya. Here the rainfall exceeds 200 cm. In some parts of Khasi and Jaintia hills, the rainfall exceeds 1,000 cm. In the Brahmaputra valley and the adjoining hills, the rainfall is less then 200 cm. AreasDIRECTION of Medium Rainfall : Rainfall between 100-200 cm is received in the southern parts of Gujarat, east Tamil Nadu, northeastern Peninsula covering Orissa, Jharkhand, Bihar, eastern Madhya Pradesh, northern Ganga plain along the sub- Himalayas and the Cachar Valley and Manipur. Areas of Low Rainfall: Western Uttar Pradesh, Delhi, Haryana, Punjab, Jammu and Kashmir, eastern Rajasthan, Gujarat and Deccan Plateau receive rainfall between 50-100 cm. Areas of Inadequate Rainfall: Parts of the Peninsula, especially in Andhra Pradesh, Karnataka and Maharashtra, Ladakh and most of western Rajasthan receive rainfall below 50 cm. Variability of Rainfall A characteristic feature of rainfall in India is its variability. The variability of rainfall is computed with the help of the following formula: C.V. = Standard Deviation x 100 Mean where C.V. is the coefficient of variation.

DIRECTIONDIRECTION Main Examination 53 INSTITUTE FOR IAS EXAMINATION The values of coefficient of variation show the change from the mean values of rainfall. The actual rainfall in some places deviates from 20-50 per cent. The values of coefficient of variation show variability of rainfall in India. A variability of less than 25 per cent exists on the western coasts, Western Ghats, northeastern Peninsula, eastern plains of the Ganga, northeastern India, Uttaranchal and Himachal Pradesh and south-western part of Jammu and Kashmir. These areas have an annual rainfall of over 100 cm. A variability of over 50 per cent exists in the western part of Rajasthan, northern part of Jammu and Kashmir and interior parts of the Deccan plateau. These areas have an annual rainfall of less than 50 cm. Rest of India have a variability of 25-50 per cent and these areas receive an annual rainfall between 50 -100 cm. Climatic Regions of India Vladimir Koppen identified with four criteria temperature, precipitation, vegetation and attitude with actual values to be the basis of classification. As per these he identified variable categories of climates represented by different alphabets A (Tropical), B (Arid), C (Subtropical), D (Temperate), E (Frigid), M (Montane) for India his scheme includes- Af TropicalDIRECTION moist monsoonal type climate that represents its associate with West Ghats and Andaman-Nicobar island in reference to very short dry Winters and rainfall well distributed Throughout the year (>200cm rainfall). Am/Aw The northern west coast experiences this monsoonal rain is identified with it. Entire interiors of peninsula experiencing monsoonal rainfall ranging between 100- 125cm with strong prevalence dry winters is included in this category barring the ex- ception coast and the rain shadow interiors. As Tropical dry summers with rainfall begin associated with retreating monsoonal with summers being dry. Coromandel coast of India. BWhw Tropical arid region less than 25cm of rainfall associate with West Rajasthan. BShw The semi arid tropical regions along the semicircular belt of North West India including Punjab, Haryana, East Rajasthan, Gujarat. Another region is the rain shadow interiors of peninsula. BSkw Semi arid temperate region incorporating Ladakh. Cwa From North plains to Assam (Brahmaputra Plains) sub tropical dry winter cli- mate with strong high temperature through out the year however amount of rainfall strongly declining from East to west.

DIRECTIONDIRECTION Main Examination 54 INSTITUTE FOR IAS EXAMINATION Dfc Temperate climate type with rainfall well distributed throughout the year and short summers Purvanchal, Garo Khansi, Jaintia Hills represents this climate. H The mountain climate associated with the Himalayan and Purvanchal regions. It is representative of altitudinal gradation of climate.

Cyclones and their Impact in India History of Cyclones in India: Although cyclones affect the entire coast of India, the East Coast is more prone compared to the West Coast. An analysis of the frequen- cies of cyclones on the East and West coasts of India during 1891-2000 show that nearly 308 cyclones (out of which 103 were severe) affected the East Coast. During the same period 48 tropical cyclones crossed the West Coast, of which 24 were severe cyclonic storms. Out of the cyclones that develop in the Bay of Bengal, over 58 percent approach and cross the east coast in October and November. Only 25 percent of the cyclones that develop over the Arabian Sea approach the west coast. In the pre-monsoon season, corresponding figures are 25 percent over the Arabian Sea and 30 percent over the Bay of Bengal. Special nature of the problem Though the frequency of Tropical Cyclones in the North Indian Ocean (NIO) are the leastDIRECTION in the world (7% of the global total), their impact on the coasts bordering the North Bay of Bengal (North of 150 N latitude) in India as well as in the Bangladesh are extremely disastrous. The problem can be fathomed from the fact that during the past two and a half centuries, 20 out of 23 major cyclone disasters (with human loss of life 10,000 or more and not considering the damages) in the world have occurred over the Indian Subcontinent (India and Bangladesh). One of the major reasons for this is the serious storm tide problem in these coasts. A tropical cyclone of specific intensity when it strikes the east coast of India and Bangladesh, usually produces a higher storm surge compared to that when such a cyclone strikes elsewhere in the world. This is because of the special nature of the coastline, the shallow coastal ocean to- pography and the characteristics of tide in the North Bay of Bengal region. Further the high density of population, low awareness of the community about cyclones and their risks, inadequate response and preparedness add to the severity of the problem. There are 13 Coastal States and UTs in the country, with about 84 coastal districts affected by tropical cyclones. Four States (Tamil Nadu, Andhra Pradesh, Orissa and West Bengal) and one UT (Puducherry) on the East Coast and one State (Gujarat) on the West Coast are the States that are more vulnerable to cyclone disasters.

DIRECTIONDIRECTION Main Examination 55 INSTITUTE FOR IAS EXAMINATION Vulnerability to Cyclones: Cyclones are natural events, which can neither be wished away nor prevented. What actually makes these hazards turn in to disasters is the vulnerability of the people and their means of livelihood and the fragility of infrastructure. The Indian Sub-continent is the worst affected part in the world as far as loss of lives is concerned though more severe cyclones do occur in other parts of the world and financial losses are much more elsewhere. This could primarily be attributed to the special nature of the problem discussed above and the vulnerability of the people. High population density, com- paratively better employment opportunities and economic compulsions force people to occupy, areas, which are susceptible to cyclones, saline ingress and flooding. Inad- equacy of infrastructure adds to their vulnerability. Traditional coping mechanisms have been the mainstay for these people to counter hazards, but during major disasters these coping mechanisms are found wanting. Though communities have a natural tendency to face hazards by joining hands, they usually fail to generate the desired synergy because of unsystematic and ad hoc approaches. On many occasions people are not even aware of the risks involved. The frequent disasters nullify the develop- ment of several years and turn the clock back for these vulnerable families. Impact on the Coastal Eco-System “CoastalDIRECTION ecosystem” includes estuaries and coastal waters and lands located at the lower end of drainage basins, where streams and river systems meet the sea and are mixed by tides. The coastal ecosystem includes saline, brackish (mixed saline and fresh) and fresh waters, as well as coastlines and the adjacent lands. All these water and landforms interact as integrated ecological units. Shore-lands, dunes, sandbars, offshore islands, headlands, and freshwater wetlands within estuarine drainages are included in the definition since these interrelated features are crucial to coastal fish and wildlife and their habitats. Mangroves are located all along estuarine areas, del- tas, tidal creeks, mud flats, salt marshes and extend over 4871 sq. km (about 7% of world’s mangrove areas). Impact of global warming- induced sea level rise due to thermal expansion is more pronounced in the Bay of Bengal due to the shallowness of the waters. The entire coastal ecosystem in general and the eastern coast in particu- lar are highly vulnerable due to flat and low terrain, high population density, over exploi- tation of natural resources, high rate of environmental degradation on account of pol- lution and non-sustainable development. On many occasions, the livelihood require- ments of people are detrimental to maintaining the delicate balance of the fragile coastal ecosystem. Degradation of the eco-system not only affects the environment adversely, but also makes the people living in the coastal areas more vulnerable.

DIRECTIONDIRECTION Main Examination 56 INSTITUTE FOR IAS EXAMINATION VEGETATION REGIONS OF INDIA

The flora of India varies considerably in different parts of the country, both in specific identity and number of species which, by bio-diversity of species, may be unequalled in any other country of the world. Therefore the comparative studies have led to the differentiation of floristic or ecological regions. In the Himalayas with their lofty heights, there is a large proportion of endemic species which are native to the ecological zone. On the basis of flora of local habitat or site, ten ecological regions are usually recognized in India. However, these ecological regions may coincide with the 17 forest types (botanical regions or provinces). The following are the ten ecological zones usually recognized: (i) Western Himalayas (ii) Eastern Himalayas (iii)North-Eastern Hills (iv) Desert Thorny Forest of the Indus Plain (v) Gangetic Plain Moist Deciduous Forest (vi) Assam Valley Tropical Evergreen to Semi-evergreen Forest (vii)Open to Dry Mixed Deciduous and Sal Forest of central India (viii)SouthDIRECTION Indian Tropical Dry Deciduous Forest (ix) West Coastal Tropical Moist Evergreen to Semi-evergreen and Moist Deciduous Forest (x) Wet Tropical Coastal Forest of Bay Islands (i) Western HIimalayas This region comprises of Jammu and Kashmir, Himachal Pradesh and Uttarakhand Hills with the climate and vegetation ranging from submontane tropical to temperate and alpine types. On the basis of vegetation available, this ecological zone has been divided into following sub-regions: (a) Submontane Forest (b) Upper West Himalayan Temperate Forest (i) Moist Temperate Forest (ii) Dry Temperate Forest and (c) Alpine Region (a) Submontane Forest This region consists of the area between 300 and 1,500 meters height and it com- prises mainly the Siwalik Hills and adjoining submontane areas of Jammu and Himachal Pradesh.

DIRECTIONDIRECTION Main Examination 57 INSTITUTE FOR IAS EXAMINATION In the hills and denuded south-facing slopes in Jammu and Himachal Pradesh are found a sub-tropical dry evergreen forest. It is primarily a mixed scrub vegetation of Acacia modesta which seems to be a pioneer species establishing itself on the open exposed and skeletal soils of this submontane dry evergreen forest. On the porous alluvium, comprising sand and shingle of riverine tracts khair, a medium-sized tree is found frequently. In this region where rainfall received is 100 centimeters annually, rich forests of sal are found. In the upper slopes of the Siwalik Hills, there are almost pure forests of chir pine. (b) Upper West Himalayan Temperate Forest (i) Moist Temperate Forest: Some of the prominent timber species are found in this zone. This is the most widespread Himalayan type, extending over the whole length of the Western Himalayas from the foothills to the tree-line bordering the snows. The chir pine continues above an elevation of 1,200 meters on the slopes of the Himalayan foothills. However, it is replaced at higher altitudes of 1,600 meters by the blue pine. It is well distributed in the Western and Central Himalaya at about 2,000 meters. It is a large evergreen tree with bluish foliage and suffers more from snow damage than any other species. It occurs in a pure form or mixed with some other species and is known for profuse natural regeneration wherever conditions are favorable. Deodar, the HimalayanDIRECTION cedar occurs in almost pure stands or occasionally as a mixture with other conifers or broadleaved trees. It is found abundantly between 1,600 and 1,900 meters height and it is a large majestic evergreen tree with a dark green to silvery, fairly dense foliage. The crown of deodar is well developed and like the blue pine it is also well known for profuse natural regeneration and can sustain snow. Further higher up occurs, a moderate sized evergreen tree, known as the oak at altitudes between 2,100 to 2,500 meters. The oak is a large sized broadleaved, evergreen tree with height up to 25 meters. It is widely distributed over the high Himalayas with a number of species known as kharsu oak, ban oak and moru oak. The oak and other broadleaved species occur in moist, shady depressions whereas the silver fir and spruce are found on exposed sites. The silver fir is widely distributed in the Western Himalayas at an altitudinal range of 2,500 to 3,500 meters or even more up to the alpine meadows or the snowline in certain well exposed areas. It is a majestic coniferous tree with a well developed crown. It occurs either in a pure form or in association with the Himalayan spruce and blue pine. Requiring fewer nutrients and equipped with defences to en- dure climatic severity, this high level fir forest marks the uppermost limits of trees in the Himalayas. The mean summer temperature is 20° C and in winter the mercury drops

DIRECTIONDIRECTION Main Examination 58 INSTITUTE FOR IAS EXAMINATION to far below the freezing point. Thus in this forest the bulk of the annual precipitation is in the form of snow that covers the ground for several weeks together. In Kashmir, the valley flat rests at 1,500 meters while the surrounding karewas and mountains soar over 5,000 meters. In the Kashmir Valley some species are common, for example, the birch, poplar, willow and chinar become visible as one leaves behind the floating and rooted hydrophytes of the lakes like Wular, Dal and Nagin. Though occurring in a discontinuous fashion, these trees attract attention, especially in au- tumn when the leaves of these trees are tinted in a color-riot with all shares of ochre, chestnut brown and amber red, lending a pictorial character to the Kashmir Valley landscape. The karewas of the Kashmir Valley are also known for saffron and walnut apart from several horticultural trees namely, apples, almonds, peaches, cherries and pomegranates. (ii) Dry Temperate Forest: In the inner dry valleys of the Main Himalayan as well as in the Trans-Himalayan regions, dry temperate forests are found. These forests are of open type, somewhat xerophytic, and they are found at heights of over 1,500 meters. Poplars and willows become stunted in Ladakh and are found near the flows of glacial melt water. Conifers including deodars and junipers predominate with scattered oak and other broadleaved trees confined to moist, shady depression. In the dry zone of the DIRECTIONCentral and Trans-Himalaya are found the almost pure forest of Neoza or Chilgoza pine with a shrub layer of plants such as Daphne oleoides and a ground layer of vari- ous grasses and oak seedlings. Further up between elevations of 3,000 to 3,600 meters are found the dry blue pine forest in the dry zone of the Central-and-Trans- Himalayas. (c) Alpine Region This region represents the uppermost limit of tree growth at over 3,300 meters and gradually merges into the region of permanent snow which is above the timber (or tree) line at 3,500 meters. The alpine region thus occupies the topmost tree zones in the Himalayas merging with the alpine shrubs near the snowline. This region is characterized by the limited growing season of 60 to 80 days with a mean summer temperature of 20° C when nature bursts into life. Then an alpine tundra of grass, flowering herbs, sedges and mosses form a rolling down landscape of alpine meadows, locally known as margs, namely Khilanmarg, Gulmarg, Tanmarg and Sonmarg. Again, when vegetation is reduced to dwarfed and stunted trees of willow and juniper, the alpine scrub makes its appearance. This happens near 3,600 meters where, spreading their fibrous roots into the rocky skeletons, these plants structurally adapt themselves to limited soil and moisture. The alpine stony desert with scree and

DIRECTIONDIRECTION Main Examination 59 INSTITUTE FOR IAS EXAMINATION bits of rock heavily encrusted with lichens and mosses occur below the snowline. Occupying the altitude between 3,700 to 4,200 meters, this zone appears to be bleak and barren; however, some species of trees like rhododendron, betula, and junipers are found in abundance on lower levels of the alpine zone. (ii)The Eastern HIimalayas This area comprises the Darjeeling Hills, Sikkim and Arunachal Pradesh. It consists of very rich and dense forests. This ecological zone is very similar to the Western Himalayas in vertical zonations in respect to climate and vegetation. The chief differ- ences are due to higher rainfall and warmer conditions (due to lower latitude) prevail- ing in the Eastern Himalayas compared to those in the Western Himalayas and hence the forests have found a natural home in this ecological zone. The type of forests which have developed in this zone are in direct response to the prevailing topographical and climatic conditions available at sub-regional levels in this ecological zone here. The sub-regions are:- (a) Submontane Evergreen Forest (b) Temperate Evergreen Forest (1) Lower Mixed Temperate Forest(2) Upper Dry Temperate Forest (c) Alpine Forest (a) SubmontaneDIRECTION Evergreen Forest This forest extends from the plains at the foot of the hill ranges to about 1,800 meters. Here, tropical trees of the sal are found in a dense form. In the riverine regions up to 900 meters, association of shisham and khair is found. Mixed forests of some decidu- ous trees are also found. There are other important sub-tropical trees and grasslands that characterize the forests of this area. (b) Temperate Evergreen Forest This zone ranges from about 1,800 to 3,500 meters. It is further divided into Lower Mixed Temperate Forest and Upper Dry Temperate Forest.The Lower Mixed Temperate Forest is a dense evergreen forest mixed with hillock, chir, blue pine or kail of the coniferous species. This mixed temperate forest is found well developed in Sikkim and in the Darjeeling Hills. The Upper Dry Temperate Forest is found above the elevation of 2,800 meters. It is cooler and is full of dominant conifers like the silver fir, spruce, oak and fir. In Sikkim and Arunachal Pradesh, there is an open forest of juniper and birch above an eleva- tion of 2,800 meters. Further up in higher regions are found the rhododendron as the dominant species. (c) Alpine Forest

DIRECTIONDIRECTION Main Examination 60 INSTITUTE FOR IAS EXAMINATION The alpine forest of the Eastern Himalayas is considered the uppermost zone and is found over the areas of 3,500 meters. However, above 3,800 meters altitude, the vegetation is generally devoid of trees. The flortistic affinities of this region have some species of Chine origin as in the West- ern Himalayas where some southwest Asian elements have entered n a broad front. This zone of alpine forest distributed all over Sikkim and Arunachal Pradesh above an elevation of 3,000 meters is the highest tree forest in the eastern Himalayas. The principal species are the deciduous like oaks, hillock, conifers like pines, silver fir, cedar, etc. and rhododendrons, the last growing to over 4,000 meters height are found in abundance. With increasing heights, most of the trees get crooked and tend to branch low down on the bole. Due to its rich flora, this region is also recognized as one of the richest floristic regions of the world, but in the inner dry valleys of Sikkim of the Zemu and Lonokh Valleys, at heights between 2,700 to 3,500 meters, mixed conifer- ous forest develops with scrub of Lareh forest further high at elevations of 3,000 meters in Sikkim and Arunachal Pradesh. (iii)North Eastern Hills This zone is composed of a series of hill ranges of Assam, Meghalaya, Tripura, Nagaland and Mizoram. This region receives the heaviest rainfall and Cherrapunji is the DIRECTIONplace that receives the heaviest rainfall in the world. The main ranges of this region are the Garo, Khasi, Jaintia, Mikir and Mishmi Hills which have a dense evergreen forest at lower heights known as (a) Khasi Sub-tropical Wet Hill Forest and (b) the Sub-tropical Pine Forest. The main constituent species of the former forest are found to be the arjun, sal, bamboo and needlewood. Further high, above the elevation of 800 meters height in the Khasi-Mikir-Jaintia-Naga Hills and Manipur is found the sub-tropical pine forest in which pine forms the main forest of which the principal species are found to be Pinus khasya or PInus insubris. (iv) Desert thorny forest of transgangetic plain This is the outer Ganga Plain comprising the desert of Western Rajasthan and desert fringe areas of Gujarat and Punjab-Haryana Plain. Here, generally dry conditions pre- vail with low rainfall (less than 75 centimeters) and wide variations in diurnal tempera- tures. The natural vegetation is degraded to intensive grassy areas in the region by human interference and at present comprise of bushy and thorny plants, namely, on the Aravali Hills. The dominant vegetation is found in association with khair and shisham. Apart from being known for light timber, both these species are very good fodder trees and they are widely developed for feeding livestock including camels.

DIRECTIONDIRECTION Main Examination 61 INSTITUTE FOR IAS EXAMINATION (v) Gangetic plain moist Deciduous forest The entire Gangetic Plain comprising Uttar Pradesh, Bihar and West Bengal has been largely stripped of the natural vegetation (for carrying on cultivation) except the foot- hills in the terai and the tidal swamps in the Ganga delta. In western Uttar Pradesh, apart from khair, the species include arjun. In eastern Uttar Pradesh and Bihar, as a whole, woodland is practically in the riverine strips and the village groves. The com- mon trees are sain, dhak, haldu, eucalyptus, tendu and mahua. Shrub forests are also met within the region which includes shrubs like Ziiyphus jujube. These trees individu- ally give a mark to the vegetation over considerable areas but they do not form any assemblages. Another sub-zone in the Gangetic Plain is the tidal swamp forest of the Sunderbans. Very prominent and luxuriant species of mangrove trees and scrub are found here. The very common trees in the village groves are neem, mango, peepal and tamarind. (vi) Assam valley tropical evergreen to semi evergreen forest. All along the northern banks of River Brahmaputra, on the alluvial deposits of Lakhimpur and in the heavy rainfall (200 to 1,000 centimeters) areas of cachar and Goalpara foothill tracts are found the species like hillock, hollong, behera, mokai and bamboo. The canopy of this forest is not very dense and individual trees may grow upto more thanDIRECTION 20 meters tall. Bamboos form dense brakes, sometimes an impenetrable thorny thicket, composed of canes, climbers and evergreen bushes. (vii) Open to dry mixed decuduous and sal forest of central India. This zone mainly comprises of Madhya Pradesh along with some parts of Orissa and Gujarat. This zone is more or less higher than that of the Indo-Gangetic Plain. This zone has small ranges, namely the Aravalis in the west, Satpuras in the southwest, Vindhyas to the north and the South Bihar Plateau to the east.The topography here is of disturbed type and the terrain witnesses the severe erosion problems. The differ- ences in distribution and intensity of rain, soil and terrain conditions, intense land-man relationships by way of lopping, felling of timber and grazing have all given rise to degraded forests here. Depending upon all these features, three types of forest have been identified. Scrub and arid type of vegetation are witnessed most frequently in central India leading to an open or thorny forest. Dry mixed deciduous forest forms the major portion of the vegetation. In favored peaks in the plateaus and in the hills of central India, the rich sal forest has developed. Along the Orissa Coast on the beaches and dune fringes, casuarinas are common.

DIRECTIONDIRECTION Main Examination 62 INSTITUTE FOR IAS EXAMINATION (viii) Southern India tropical dry Deciduous forest. This ecological zone lies to the south of the central Indian zone. This zone includes parts of the states of Maharashtra, Andhra Pradesh, Tamil Nadu, Karnataka and Kerala. In this zone the annual mean temperature lies between 24° and 28° C and the total rainfall received is less ranging from 75 to 100 centimeters. In this drier part of southern India, the area is blessed with the forests of teak. The central region with the Nilgiri Hills and Tamil Nadu Highlands has floral species of sandalwood and harra. (ix) West coast tropical moist evergreen to semi-evergreen and moist Decidu- ous forest This zone is all along the Western Ghats, called the Konkan Coast in the north and the Malabar Coast in the south. This west coast extends from the Gujarat Coast in the north to Kannyakumari in the south. This area receives very heavy rainfall from the moist-bearing South West Monsoon winds from the Arabian Sea. The Western Ghats and the Nilgiri Hills are the two prominent mountain ranges of this region. The hill tops of these two ranges form the Tropical Moist Evergreen Forests which are indeed very luxuriant in floral diversity and multi-storeyed growth. The trees grow to a height of 30 to 35 meters forming close canopies. The undergrowth has bamboo and canes on wetDIRECTION ground. The ground species are few with little grass. Shisham and sain are the important species. The west coast semi-evergreen forest is found in the Western Ghats forming a narrow strip between the evergreen and the moist deciduous. Several im- portant wood species, namely shisham, rosewood and moist teak occur in this narrow subzone. The most deciduous forest occurs along the Western Ghats and in the moist shady depressions of the Deccan plateau. The proportion of evergreen species in this subzone is more than that in the tropical semi-evergreen forest mentioned above. (x) Wet tropical coastal forests of bay islands The Andaman and Nicobar Islands in the Bay of Bengal form a distinct ecological zone. The floristic affinities of these islands have links with the Malaysian realms. The islands comprise the climate of the typical tropical coast type and they receive very heavy rainfall. Rainfall is almost evenly spread out all through the year and the mean annual temperature is about 26 C. All these conditions provide a climax giant ever- green forest to semi-evergreen in this ecological zone. Dab, dipterocarb, mayera and gumer form a few of the prominent species of this zone. In the giant evergreen forest of the Andamans are found the various magnitudinal epiphytic growths of climbers, shrubs and ferns.

DIRECTIONDIRECTION Main Examination 63 INSTITUTE FOR IAS EXAMINATION INDIAN SOIL

India being large country exhibits variety of soil types. Due to diversity of parent rock material, variation of climatic conditions and soil forming processes, soil character varies from region to region. The soils of peninsular India are mostly zonal soils formed by disintegration and decomposition of rocks in situ. On the other hand soils of plains are azonal soil transported and deposited by rivers. The major classification of soil includes – (a) Alluvial – developed due to process of deposition of sand, silt and clay in layers. These are found along river courses in low lying tracts. Alluvial soils are classified into newer alluvium (Khader), older alluvium (Bhanger) and pebble sand deposits (Bhaber). Bhanger marks their development only in the regions where flood water do not reach pronouncedly. A few metres below the surface, the bhanger has bed of fine nodules or Kankar. There are other variants regionised like Usar soil in Ganges Ghaghara doab, bhur soil in Ramganga tract, bhat soil in lower Gandak valley Bhaber and terai at the foot of Shivalik. Bhur is sandy in character, bhat is a whitish calcareous soil while bhabar is a sandy soil with a high porosity and low moisture retaining capacity. Although fertility of alluvial soil is dependent on many factors like texture,DIRECTION organic matter and mineral content, these are the best agricultural soils in India. This occupies all the plains of India. (b) Black soil – is dark color soil due to high content of humus calcium, magnesium carbonates and iron oxides. These are developed from basaltic rocks and are commonly known as regur or black soil. They are prominent over Maharashtra, Malwa, Khahawar, Telengana, Malnads, Piedmont uplands of Tamil Nadu. (c) Red – is formed by weathering of ancient crystalline and metamorphic rocks. These are found in areas of low rainfall and high temperature. These are lessleached than laterite. The colour is due to high iron content. Red soil covers large parts of Tamil Nadu, southern Karnataka, Andhra Pradesh, Madhya Pradesh and Orissa. The soils are poor in phosphorous, nitrogen and lime content. (d) Laterite – are constituted of ferruginous aluminous elements formed in regions of heavy seasonal rainfall accompanied by high temperature conditions for most part of the year. The top soil is completely leached out leaving a high proportion of iron and aluminium as residue. Laterite soil is poor in phosphorous, potassium lime and nitro- gen. The PH ranges from 4.5 to 5.5 and the base exchange capacity is low. The soil is reddish in color due to presence of iron oxides. Laterite soils are found in Orissa,

DIRECTIONDIRECTION Main Examination 64 INSTITUTE FOR IAS EXAMINATION western West Bengal, in some parts of Andhra Pradesh, Meghalaya and Bihar Jharkhand plateau. (e) Desert soil – are characterized by sandy texture. They are usually adequate in mineral status but poor in organic matter. The pH value is high. These are typical of Rajasthan, parts of Guajarat, Punjab and Haryana where annual rain is less than 40 cm which does not encourage chemical decomposition of crystal elements. (f) Montane soil - are found in Himalayas and hills of drier regions of peninsula and in parts of Andaman islands. The terai soils of Himalayan foothills are rich in nitrogen and organic matter. In coniferous forest belt of Jammu & Kashmir, Himachal Pradesh, Uttranchal and Sikkim, brown podzol soils are found. Alpine meadow soils are lo- cated at further higher altitudes. Further mountain soils having good vegetation cover its rich in organic matter. But their base status varies de pending on the degree of leaching. (g) Saline and Alkaline – are found in drier parts of country. Being deficient in under- ground drainage capillary action during summer brings the concentrated dissolved salts to the surface where they form a white crust. (h) Peat and Bog – These are found in humid regions as a result of accumulation of a largeDIRECTION amount of organic matter in the soil. The soil is deep black is color with a high clay content and is rich in nitrogen adequate in potash, but deficient in phosphorus and are poorly drained.

BIOGEOGRAPHY REALMS

A major goal of ecology is to understand various factors influencing the present distri- bution and abundance of animals and plants (Andrewartha and Birch 1954; Krebs 1972; MacArthur 1972). The study of the geographical distributions of plants and animals, respectively, are termed phytogeography and zoogeography. Biogeography encompasses the geography of all organisms and involves a search for patterns in the distributions of plants and animals and an attempt to explain how such patterns arose during the geological past. In addition to classifying present dis- tributions, biogeographers seek to interpret and to understand past movements of organisms. Ecology and biogeography are closely related and overlapping disciplines and have profoundly affected one another.

DIRECTIONDIRECTION Main Examination 65 INSTITUTE FOR IAS EXAMINATION Global Realms

When early naturalists traveled to different parts of the world, they quickly discovered distinctly different assemblages of species. As data were gathered on these patterns, six major biogeographic “realms” or regions were recognized, three of which corre- spond roughly to the continents of Australia (Australian), North America north of the Mexican escarpment (Nearctic), and South America south of the Mexican escarpment (Neotropical). (The Neotropical region also includes the Antilles.) Africa south of the Sahara is known as the Ethiopian region. Eurasia is divided into two regions, the Palearctic north of the Himalayas (which includes Africa north of the Sa- hara desert) and the Oriental south of the Himalayas (India, southern China, Indochina, the Philippines, and Borneo, Java, Sumatra, and other islands of Indonesia east to, and including, the Celebes).

Each of the six biogeographic regions is separated from the others by a major barrier to the dispersal of plants and animals, such as a narrow isthmus, high mountains, a desert, an ocean, or an oceanic strait. There is generally a high degree of floral and faunal consistency within regions and a marked shift in higher taxa such as genera andDIRECTION families in going from one region to another. Although biogeographers familiar with different plant and animal groups often disagree on the exact boundaries be- tween regions , there is broad agreement on the usefulness of recognizing these six major regions. High species diversities in the tropics, among other things, have led to the notion that speciation rates in these areas must be extremely high and that such regions often constitute “source areas” for production of new species, many of which then migrate into less hospitable areas, such as the temperate zones. Thus, Darlington (1957, 1959) proposed the “area-climate hypothesis,” which states that most domi- nant animal species have arisen in geographically extensive and climatically favor- able areas; he considered the Old World Tropics, which include the tropical portions of the Ethiopian and Oriental regions, to be the major source area for most vertebrate groups and argued that such dominant forms have migrated centrifugally to other smaller and less favorable areas, including Europe, North and South America, and Australia.

Classical biogeography has produced several so-called biogeographic rules based on recurring patterns of adaptation of organisms. Thus, homeotherms living in cold

DIRECTIONDIRECTION Main Examination 66 INSTITUTE FOR IAS EXAMINATION climates are often larger than those from warmer regions. Such a trend or cline can even be demonstrated within some wide-ranging species.

This tendency, termed Bergmann’s rule after its discoverer, has a probable causal basis in that large animals have less surface per unit of body volume than small ones, resulting in more efficient retention of body heat. Many other biogeographic rules have also been proposed, all of which are basically descriptive. Allen’s rule states that the appendages and/or extremities of homeotherms are either longer or have a larger area in warmer climates; a jackrabbit, for example, has much longer and larger ears than an arctic hare. The presumed functional significance is that large appendages, having a larger relative surface area, are better at heat dissipation than smaller ones. Another rule (Gloger’s) asserts that animals from hot, dry areas tend to be paler than those from colder, wetter regions. Still another biogeographic rule is that fish from colder waters often have more vertebrae than those from warmer waters. The adaptive significance of many of these biogeographic trends remains obscure, al- though such geographically variable phenotypic traits are frequently developmentally flexible and respond more or less directly to temperature.

IndianDIRECTION Realms India, with varied terrain, topography, land use, geographic and climatic factors, can be divided into ten recognizable biogeographic zones (Rodgers 2000). These zones encompass a variety of ecosystems mountains, plateaus, rivers, forests, deserts, wetlands, lakes, mangroves, coral reefs, coasts and islands. Trans-Himalayan Region, constituting 5.6 per cent of the total geographical area, includes the high altitude, cold and arid mountain areas of Ladakh, Jammu & Kashmir, North Sikkim, Lahaul and Spiti areas of HimachalPradesh. This zone has sparse alpine steppe vegetation that harbors several endemic species and is a favor- able habitat for the biggest populations of wild sheep and goat in the world and other rare fauna that includes Snow Leopard (Uncia uncia) and the migratory Blacknecked Crane (Grus nigricollis). The cold dry desert of this zone represents an extremely frag- ile ecosystem. Himalayan Zone, in the far North, constituting 6.4 per cent of the total geographical area includes some of the highest peaks in the world and makes India one of the richest areas in terms of habitats and species. The steep slopes, unconsolidated soils and intense rainfall render the zone extremely fragile. The alpine and

DIRECTIONDIRECTION Main Examination 67 INSTITUTE FOR IAS EXAMINATION sub-alpine forests, grassy meadows and moist mixed deciduous forests provide diverse habitat for endangered species of bovids such as Bharal (Pseudois nayaur), Ibex (Capra ibex), Markhor (Capra falconeri), Tahr (Hemitragus jemlabicus), and Takin (Budoreas taxicolor). Other rare and endangered species restricted to this zone include Hangul (Cervus eldi eldi) and Musk Deer (Moschus moschiferus) Indian Desert Zone, constituting 6.6 per cent of the total geographical area, includes the Thar and the Kutch deserts and has large expanses of grassland that supports several endangered species of mammals such as Wolf (Canis lupus), Caracal (Felis caracal), Desert Cat (Felis libyca) and birds of conservation interest viz., Houbara Bustard (Chamydotis undulate) and the Great Indian Bustard (Ardeotis nigriceps). Semi-arid Region, constituting 16.6 per cent of the total geographical area, is a tran- sition zone between the desert and the dense forests of Western Ghats. Peninsular India has two large regions, which are climatically semi-arid. This semi-arid region also has several artificial and natural lakes and marshy lands. The dominant grass and palatable shrub layer in this zone supports the highest wildlife biomass. The cervid species of Sambar (Cervus unicolor) and Chital (Axis axis) are restricted to the better wooded hills and moister valley areas respectively. The Lion (LeoDIRECTION persica), an endangered carnivore species (restricted to a small area in Gujarat), Caracal (Felis caracal), Jackal (Canis aureus) and Wolf (Canis lupus) are some of the endangered species that are characteristic of this region. Western Ghats, constituting 4.0 per cent of the total geographical area, is one of the major tropical evergreen forest regions in India. The zone stretches from the hills to the South of the Tapti River in the North to Kanyakumari in the South and in the West, this zone is bound by the coast. This zone represents one of the biodiversity ‘hot spots’ with some 15,000 species of higher plants, of which 4,000 (27 per cent) are endemic to the region. The Western Ghats harbour viable populations of most of the vertebrate species found in peninsular India, besides an endemic faunal element of its own. Significant species endemic to this region include Nilgiri Langur (Presbytis jobni), Lion Tailed Macaque (Macaca silenus), Grizzled Giant Squirrel (Ratufa macroura), Malabar Civet (Viverricula megaspila), Nilgiri Tahr (Hemitragus bylocrius) and Malabar Grey Hornbill (Ocycerous griseus). The Travancore Tortoise (Indotestudo forstem) and Cane turtle (Heosemys silvatica) are two endangered taxa restricted to a small area in central Western Ghats. Deccan Plateau, constituting 42 per cent of the total geographical area, is a semi- arid region that falls in the rain shadow area of the Western Ghats. This

DIRECTIONDIRECTION Main Examination 68 INSTITUTE FOR IAS EXAMINATION bio-geographic zone of peninsular India is by far the most extensive zone, covering India’s finest forests, particularly in the States of Madhya Pradesh, Maharashtra and Orissa. Majority of the forests are deciduous in nature but there are regions of greater biological diversity in the hill ranges. The zone comprising of deciduous forests, thorn forests and degraded scrubland support diverse wildlife species. Species such as Chital (Axis axis), Sambar (Cervus unicolor), Nilgai (Boselapbus tragocamelus) and Chousingha (Tetracerus quadricornis) are abundant in this zone. Some other species like Barking deer (Muntiacus muntjak) and Gaur (Antilope cervicapra) are more fre- quent in, or are restricted to moister areas, but are still found in fairly large numbers. Species with small populations include the Elephant (Elephas maximus) in Bihar-Orissa and Karnataka-Tamil Nadu belts.

10 BIOGEOGRAPHIC ZONES OF INDIA DIRECTION

Gangetic Plain, constituting 10.8 per cent of the total geographical area, is a flat alluvial region lying to the North and South of the Ganga River and its major tributaries and in the foothills of the Himalayas. The Gangetic plain is topographically homog- enous for hundreds of kilometers. The characterstic fauna of this region include Rhino (Rhinoceros unicornis), Elephant (Elephas maximus), Buffalo (Bubalus bubalis), Swamp Deer (Cervus duvauceli), Hog-Deer (Axis porcinus) and Hispid Hare (Carprolagus

DIRECTIONDIRECTION Main Examination 69 INSTITUTE FOR IAS EXAMINATION bispidus). This zone gains considerable ecological significance in the context of increasing industrialization and pollution and the consequent environmental degrada- tion and deforestation. North-East Region, constituting 5.2 per cent of the total geographical area, represents the transition zone between the Indian, Indo-Malayan and Indo-Chinese bio-geographical regions as well as being a meeting point of the Himalayan mountains and peninsular India. The North-East is thus the biogeographical ‘gateway’ for much of India’s fauna and flora and also a biodiversity hotspot. A diverse set of habitats coupled with long term geological stability has allowed the development of significant levels of endemism in all animal and plant groups. Many of the species contributing to this biological diversity are either restricted to the region itself, or to the smaller localized areas of the Khasi Hills. The country’s extensive Coasts, constituting 2.5 per cent of the total geographical area with sandy beaches, mangroves, mud Nepenthes Khasiana - commonly known as Pitcher Plant flats, coral reefs and marine angiosperm pastures make them the wealth and health zones of India. The coastline from Gujarat to Sunderbans is esti- mated to be 5,423 km long. A total of 25 islets constitute the Lakshadweep, which are of coral origin, and have a typical reef lagoon system, rich in biodiversity. However, the denselyDIRECTION populated Lakshadweep islands virtually have no natural vegetation. Andaman and Nicobar Islands, constituting 0.3 per cent of the total geographical area are one of the three tropical moist evergreen forests zones in India. The islands house an array of flora and fauna not found elsewhere. The elongated North-South oriented groups of 348 Andaman Islands have a biogeographical affinity with Myanmar. The Nicobar Islands, lying only 90 kms away from Sumatra have much stronger Indo- nesian and South-East Asian elements. These islands are centres of high endemism and contain some of India’s finest evergreen forests and support a wide diversity of corals. However, endemic island biodiversity is found only in the Andaman and Nicobar Islands. Wetlands occur in various geographical regions such as the cold arid zones of Ladakh, warm arid zones of Rajasthan, tropical monsoonic Central India, North Eastern region, South peninsular region and the coastal wetlands. India is home to several well known large mammals including the Asian Elephant, Bengal Tiger, Asiatic Lion, Leopard, Sloth Bear and Indian Rhinoceros, often engrained culturally and religiously often being associated with deities. Other well known large Indian mammals include ungulates such as the rare Wild Asian Water buffalo, com- mon Domestic Asian Water buffalo, Nilgai, Gaur and several species of deer and antelope. Some members of the dog family such as the Indian Wolf, Bengal Fox,

DIRECTIONDIRECTION Main Examination 70 INSTITUTE FOR IAS EXAMINATION Golden Jackal and the Dhole or Wild Dogs are also widely distributed. However,the dhole also known as the whistling hunter are the most endangered top Indian carni- vore, and Himalayan Wolf is now critically endangered endemic species to India. It is also home to the Striped Hyena, Macaques, Langurs and Mongoose species.

THE COASTAL GRASSLANDS

The grassland vegetation that is unique to the coastal regions across the world so far has not found any place in the classification of grassland communities. These are mostly found as gregarious single species communities. Such grasslands can be broadly classified into the following categories: (a) Grasslands of the sea beaches: The grasslands found on sea beaches can be broadly classified into the following: 1. Mainland beaches: These are grasslands communities found on the sea beaches of the tropical coasts. The most important grass species in these grasslands is the Rolling Dallis grass (Spinifex littoreus) which spreads along the sand dunes and beach sand over large areas with its long rhizomatous stolons. The male and fe male inflorescences are found on separate plant colonies. The female has large globularDIRECTION spiny inflorescences which once detached from the plant can roll in the wind along the beach sand thus enabling its dispersal. They are circum-global in nature and are found usually in pure patches or intermixed with Ipomoea pes-caprae on most of the undisturbed beaches in the equatorial regions of Asia, Africa and the Americas. Trachys muricata is another important grass species found on sea beaches. Stenotaphrum dimidiatum also form dense mats under coconut groves situated near the seashores. 2. Island beaches: Seashores of the islands across the world are inhabited by a short grass community of Thuarea involucrata, another dioecious grass species with long running stolons. They are seen as patches of green carpets on the sea beaches especially in the Andaman & Nicobar Islands and Lakshadweep. The fruit of this grass has a protrusion which grows into the sand thus enabling the germination of its seeds in the hostile environment. (b) Salt marsh grassland: These are grasslands dominated by Aleuropus lagopoides found in extensive patches on saline areas frequently submerged by tidal waters of the seas. The Rann of Kachchh is one of the major habitats of this commu- nity and is found as pure gregarious population as well as associated with other herbaceous salt tolerant plants like Sueda fruticosa. Aleuropus lagopoides is

DIRECTIONDIRECTION Main Examination 71 INSTITUTE FOR IAS EXAMINATION characterized by long rhizomatous stolons bearing stems with short and narrow leaves with a terminal globose whitish inflorescence. This grass has been red-listed on account of small number of herbarium collections in the past but later on it was found that this status was as a result of under-exploration and the plant is found abundantly at several localities of coastal salt pans on the western and eastern coast of India. (c) Mangrove grasslands: These are grassland communities found along the marshy intertidal zone of the coastal regions and are usually found in patches between adja- cent mangrove forests or areas close to sea beaches. The major grasses found in the community are Myriostachya wightiana, Zoysia matrella, Sporobolus virginicus, Halopyrum mucronatum and Porteresia coarctata, usually as monospecific patches. They are also found on the field bunds of cultivation or prawn hatcheries located near such mangrove zones. The mangroves of Bhitarkanika, Sunderbans, Pichavaram on the east coast and the mangroves of Goa, Bombay, Calicut, Kadalundi, Payyannur, and Quilon on the west coast are some of the areas where one or more of these species can be found Zoysia matrella and Sporobolus virginicus can also be found near non-mangrove sea shores of Kanyakumari and areas which has an oceanic his- tory close to it.

THEDIRECTION RIVERINE ALLUVIAL GRASSLANDS

The riverine alluvium along the banks of major rivers is usually colonized by a primary successional tall grassland community dominated by Saccharum spontaneum, locally known as Kans. This grass has long stolons which spread across vast stretches of alluvial beds of the rivers. This primary successional community often gives way to riverine tree vegetation as one moves away from the flood bank. Such grasslands are common along the Ganga and Brahmaputra rivers and also in several other rivers in peninsular India like the Mahanadi, Godavari, Cauvery, Krishna, Narmada and Bharatapuzha. The rivers of the Punjab also have such riverine alluvial grasslands. Such grasslands in Northern India are also dominated by Saccharum bengalense (Munj), which forms regular dense clumps. These grasslands are a visible treat while in flowering with the white silky showy panicles of Saccharum spontaneum and pink coloured effuse compound feathery panicles of Saccharum bengalense. These grass- lands are also habitat to a variety of birds and mammals. Saccharum bengalense serves as an important livelihood source for villagers by means of harvest of the culms for thatching and weaving of baskets, chairs, ropes and many other artifacts. Ecologi- cally, they provide soil binding services stabilizing and preventing the river beds and

DIRECTIONDIRECTION Main Examination 72 INSTITUTE FOR IAS EXAMINATION banks from erosion. The grasslands of Kaziranga National Park south of the Brahmaputra are also an example of riverine alluvial flood plain grasslands.

MONTANE GRASSLANDS The mountainous regions of the country have different types of grassland commu- nities based on their altitude, slope, aspect and rock strata. They occur as multi- species herbaceous communities over large tracts of land as well as intermixed with shrubs or as undergrowth in open to moderately dense forest areas. The montane grasslands of India can be broadly recognized into the following categories: a. Himalayan Sub-tropical grasslands: These are grasslands found on the south- ern slopes of the Himalaya between an altitudinal range of 1000 to 1800 m and are usually found on steeper rocky slopes with shallow soils. They are also found as lush undergrowth in Pine forests during the rainy season. These grasslands are domi- nated by Chrysopogon fulvus and Arundinella nepalensis along with Pennisetum orientale, Apluda mutica, Heteropogon contortus, Cymbopogon distans, Imperata cylindrica, Capillipedium parviflorum, Micostegium ciliatum and several other spe- cies of grasses, legumes and herbs from other families. These grasslands are highly vulnerable to forest fires during the dry summer season, but being fire hardy, the new shootsDIRECTION soon emerge from the underground rootstock providing valuable fodder to the grazing wild herbivores and domestic livestock during the lean season. These grass- lands are used by the local communities for fodder collection during the winter after the seeds have fallen and stored for making hay for future use. b. Himalayan Temperate grasslands: These are grasslands found on the slopes of the Himalayas in an altitudinal range of 1800 to 3000 m and are usually found on rocky slopes with shallow soils where there is sparse tree growth. These grasslands are dominated by Chrysopogon gryllus, Andropogon tristis, Themeda anathera, Themeda tremula, Erianthus rufipilus, Miscanthus nepalensis, Brachypodium sylvaticum, Bromus unioloides and several other grasses, sedges and are also rich in terrestrial orchids such as Satyrium nepalense, Herminium lancium and Habenaria intermedia. Asteraceae members such as Erigeron and Anaphalis also dominate such grasslands. The blades of Chrysopogon gryllus are used by the villagers for thatching purposes. c. Alpine meadows: The grasslands found above the tree line on the southern face of the Greater Himalaya above an altitude of 3000 m and upto 5200 m are usually referred to as the Alpine meadows. They are known as Marg in Kashmir, Bugyal in Uttarakhand and by various other local names across the mountain range. Being above

DIRECTIONDIRECTION Main Examination 73 INSTITUTE FOR IAS EXAMINATION the tree line, these grasslands extend over several square kilometers and are usually under snow for a large part of the year and thus form a climatic climax community. However, certain lower sub-alpine areas also have similar grasslands forming edaphic climax due to the rocky substrata unsuitable for tree growth. The most dominant spe- cies found in these Alpine meadows is Danthonia cachemyriana, which provides ni- trogen rich fodder to grazing sheep and other livestock and also to wild herbivores. The other major grasses include different species of Poa, Festuca, Bromus, Briza, Calamagrostis, Agrostis, etc. and also a plethora of herbaceous plants belonging to Rosaceae, Fabaceae, Asteraceae, Caryophyllaceae, Campanulaceae, Saxifragaceae, Lamiaceae, Apiaceae, Srcophulariaceae, and Orchidaceae. The alpine meadows are very rich in a variety of medicinal plants which are harvested by the local communities to sustain their livelihoods. Some of the shrubs such as Rhodo- dendron anthopogon, Rhododendron campanulatum, Juniperus, Cotoneaster, Cassiope fastigiata, Lonicera spp., etc. also are found intermixed with these grass- lands. The Chhipla Kedar alpine meadows in Pithoragarh district and Bedini Bugyal of Chamoli district of Uttarakhand are among the most extensive and contiguous patches of alpine meadows found in the Himalaya, each of which is above 300 sq km in expanse. The alpine meadows above 3800 m also forms the habitat of the highly valuableDIRECTION Yar-tsa Gambu or the caterpillar mushroom (Ophiocordyceps sinensis), which is harvested soon after snow melt before the grasses grow to cover them up. d. Trans-Himalayan steppes: These are alpine meadows found in the northern face of the Great Himalaya, usually known as the Trans-Himalaya. These areas on account of their location in the rain-shadow region of the South West Monsoons, are arid and very cold due to their proximity to Tibetan plateau and very high altitudes usually above 4000 m asl. Such grasslands are found in Ladakh in Jammu & Kashmir, Lahul, Spiti and Kinnaur districts of Himachal Pradesh and in Nilang, Niti, Malla Johar, Malla Darma and Lapthal areas of Uttarakhand, and Tso Lhamu plateau of Sikkim. These grass- lands are dominated by short grasses which can be classified as ‘Steppe’ as per the global classification of grasslands. The major species include Elymus nutans, species of Stipa, Agropyron, Poa, Calamagrostis, and Festuca along the thorny bushes such as Caragana, Astragalus, Lonicera and also Juniperus, Ephedra and several herbs of various families e.g. Asteraceae, Saxifragaceae, Caryophyllaceae, and Scrophulariaceae. Grasses such as Leymus secalinus are found towards the Tibetan plateau which is a major fodder for the Tibetan Wild ass. Orinus thoroldii is found in sandy areas and on sand dunes of the cold deserts of the Satluj and Indus basins. These areas are often interspersed with lakes and marsh meadows dominated by

DIRECTIONDIRECTION Main Examination 74 INSTITUTE FOR IAS EXAMINATION Kobresia sedge and also grasses, e.g. Colpodium, Puccinella, and Catabrosa aquatica. The Trans-Himalayan grassland communities of India are mostly extensions of the Tibetan floral elements. e. Grasslands of the North East Hills: These are found in sub-tropical to temper- ate areas of the North Eastern Hill States south of the Brahmaputra. The major grass- lands include Dzukou valley in Nagaland and Manipur, Ukhrul grasslands of Manipur, Saramati grasslands of Nagaland, and the rolling downs of Shillong. These grass- lands are characterized by a mixture of floral elements of the Himalayan region, South East Asia and peninsular India and hence form a unique biodiversity rich area. These grasslands are dominated by species of Festuca, Bromus, Arundinella, Agrostis, Cyathopus, Coix, Tripsacum, Cymbopogon, Themeda villosa, Microstegium, Glyceria, and Gymnopogon. The higher altitudes are also rich in orchids and lilies, species of Aconitum, Fritillaria, and Selinum. The lower hill slopes are rich in species of Micostegium, Erianthus, Narenga fallax, Thysanolaena maxima and a variety of mon- tane bamboos. f. Grasslands of Central Highlands: These grasslands are found in the Central Indian highlands viz., Vindhyas and Satpuras. These hill ranges are considered the corridors between the Western Ghats and the Himalayas for migration of species. TheseDIRECTION grasslands are found intermixed with tropical dry deciduous forests on rocky patches among sparse to open tree growth and can be ideally called montane or hill savannas. The grasslands on steep slopes of Vindhyan ranges is dominated by Tripogon jacquemontii, which is found drooping down the slopes. The plateaus of Satpura ranges especially the Pachmarhi plateau has several grasses such as Manisuris forficulata, Arthraxon, Pennisetum, Diectomis, Schizachyrium, Cymbopogon, Themeda, Eragrostis and Dimeria species. g. Western Ghats: The grasslands of the Western Ghats are found on the rocky hill slopes, the high altitude rolling downs and on rocky plateau tops. These grasslands can be broadly classified into the following categories: 1. Plateaus of North Western Ghats: These are grasslands found on the plateaus of the Western Ghats in Karnataka, Goa, and Maharashtra. They are usually short grasses and are ephemeral in nature seen as a green flush during the monsoons and thereafter drying up the seeds dispersed waiting for the rainfall next monsoon. Such grassland communities are common in Panchgani, Mahabaleshwar, Ratnagiri, and Kaas plateau. Dimeria, Ischaemum, Manisuris, Arthraxon, Heteropogon, Arundinella and Jansnella along with several other herbaceous plants belonging to Gentianaceae,

DIRECTIONDIRECTION Main Examination 75 INSTITUTE FOR IAS EXAMINATION Fabaceae, Asteraceae, Melastomaceae, Scrophulariaceae and Lamiaceae domi- nate these grasslands. 2. Shola grasslands: These are high altitudes grasslands of the Western Ghats having an altitude of above 1800 m upto the highest peak of Anaimudi at 2695 m above mean sea level. These grasslands are found between the shola forest patches that occur in the depressions created by watercourses flowing in these rolling downs. The shola grasslands are dominated by Eulalia phaeothrix, Dichanthium polyptychum, Chrysopogon hackelli, Chrysopogon as per, species of Agrostis, Andropogon, Arundinella, Garnotia, Jansnella, Eragrostis, Poa, and Helictotrichon along with sev- eral species of the Strobilanthes complex of Acanthaceae and several other families including Orchidaceae, Gentianaceae, Asteraceae, and Fabaceae. The grasslands of Eravikulam National Park, Mukurti Sanctuary, Kodajadri, Bababudangiri, Agastyamalai, and Poochipara in Silent Valley National Park are all examples of shola grasslands. Unlike the plateau grasslands of Northern Western Ghats, these grass- lands receive heavy rainfall throughout the year. One of the important tree species found at the edges of these grasslands is Rhododendron arboreum ssp. nilgiricum. 3. South Western Ghats: The slopes of south Western Ghats of Waynad and Idukki districts of Kerala have more of forest grasses such as Spodipogon rhizophorus, spe- ciesDIRECTION of Garnotia, Zenkeria, and Arundinella and also vast stretches of Pennisetum pedicellatum and Pennisetum polystachyon. Several species of Cymbopogon, Chrysopogon and Themeda are also very common in these grasslands. Vetiveria lawsonii is found in abundance in the grasslands of the Kabini in Nagarhole National Park. Short grasses such as Lepturus repens are also found in abundance as under- growth in Bandipur, Nagerhole and Wynad wildlife sanctuaries. Ischaemum zeylanicolum dominates the undergrowth of forest areas at many places. Dimeria spp. are found in large expanse on rocky hills and their ephemeral flowering is a great delight to the eyes. Jansenella griffithiana, Silentvalleya nairii and Chandrasekharania keralense are some of the unique grasses found here. Arundina gramini folia is a unique orchid found in the grasslands of Silent Valley. h. Eastern Ghats: The grasslands of the Eastern Ghats are comparatively drier due to lesser rainfall and lower altitudes of around 700 m above mean sea level. They are highly discontinuous and in small patches unlike the Western Ghats. The major grass community is dominated by Arundinella setosa in the higher altitudes and Aristida adscencionis, Heteropogon contortus, Sporobolus, Themeda, Chrysopogon, etc. in lower areas. The Shevroy hills of Yercaud, Javadi hills and Malkangiri represent such grassland communities.

DIRECTIONDIRECTION Main Examination 76 INSTITUTE FOR IAS EXAMINATION i. Montane bamboo brakes: These are grassland communities dominated by gre- garious dwarf monopodial bamboo species, which when one looks from a distance gives the appearance of a normal grassland. These bamboos may be 1 to 5 metres tall depending on the species. The Arundinaria densiflora brakes of Western Ghats. Arundinaria hirsuta brakes of Khasi hills, Arundinaria rolloana brakes of Dzukou valley in Nagaland and Yushania anceps brakes in the sub-alpine regions of Uttarakhand are some of the examples of montane bamboo brakes. They provide suitable habitat to a variety of pheasants and other birds and mammals and the young shoots are also food to a variety of animals including bears and rodents.

SUB-HIMALAYAN TALL GRASSLANDS IN TERAI REGION

These hygrophilous grasslands are found along the length of the Sub-Himalayan belt where the slopes of the foothills converge with the plains of the Gangetic basin. These regions are rich in artesian springs making it ideal for tall grasses. The term Terai refers to this naturally irrigated belt of land and extends from Jammu till Arunachal Pradesh. The major grass species include Narenga porphyrocoma, Saccharum bengalense, Saccharum spontaneum, Erianthus ravennae, Phragmites australis, ArundoDIRECTION donax, Cymbopogon flexuosus, Vetiveria zizanoides, Arundinella bengalense, Bothriochloa bladhii, Sorghum nitidum, Chionachne koenigii, and Ciox lachryma-jobi. The Terai grasslands are facing a severe threat due to draining out of water for irriga- tion purposes, land filling and development activities and rapid urbanization. The Terai grasslands are excellent habitat for the Great One-horned rhinoceros, which are present is limited to the flood plains of Assam, West Bengal and a few introduced populations in Dudhwa National Park in Uttar Pradesh.

TROPICAL SAVANNAS These are vast stretches of tall tropical grasslands interspersed with isolated or groups of trees and are found in Central and Western India. The tropical savannas of India can be broadly classified into the following: a. Desert Savannas: These are savannas found in the Great Indian Thar Desert and are dominated by Lasiurus scindicus which is a good soil binder and sand dune stabilizer. Trees of Prosopis cineraria are found as isolated individuals or small groups. These grasslands are found in the Desert National Park and make a good habitat for the Great Indian Bustard and other animals. The Asiatic Cheetah Acinonyx jubatus once used to inhabit these grasslands before it became locally extinct. Aristida spp.,

DIRECTIONDIRECTION Main Examination 77 INSTITUTE FOR IAS EXAMINATION Sehima nervosum and Cenchrus biflorus are some of the other dominant grasses found here. Stipa grostisplumosa is a dominant genus found on the sand dunes of the Thar Desert. b. Tropical savannas of Peninsular India: These grasslands are found almost all over the Deccan plateau and Western India. They are dominated by Sehima nervosum and Dichanthium annulatum along with a plethora of other tall and small grasses such as Eremopogon foveolatus, Pollinia fimbriata, species of Bothriochloa, Cymbopogon, Mnesithea, Rottboelia, Sorghum, Triplopogon ramossissimus, Dimeria, and Eulalia. The grasslands of Saurashtra in Western Gujarat represent one of the largest stretch of Tropical savannas of Peninsular India. The Deccan plateau areas of Karnataka and Maharashtra also have several patches of Tropical Savannas and form good habitat for several herbivores such as black buck and also birds like the Great Indian Bustard and Lesser Florican. c. Northern Tropical Hill Savannas: these are found as vast stretches of grass- lands on hill slopes in the tropical areas of Northern India such as the Aravalis, Shiwaliks and the south facing slopes of the sub-Himalayan foothills. These grasslands are of- ten intermixed with tree species such as Acacia spp., Buchanania latifolia, Dalbergia oojenensis and Anogeissus latifolia. The sub-Himalayan tropical hill savannas and ShiwaliksDIRECTION are dominated by Chrysopogon fulvus, Neyraudia arundinacea, Arundinella bengalensis, Aristida cyanantha, Heteropogon contortus, and Imperata cylindrica where as the Aravallis have more of Cenchrus spp., Aristida adscencionis, Panicum, Chloris virgata, Eremopogon an Dichanthium annulatum. d. Closed Sal Forest Grasslands: This is a unique kind of grasslands found amidst Sal forests of the sub-Himalayan belt and also in Central India. These are closed grassland communities surrounded by Sal forests on all sides and are dominated by grasses like Narenga porphyrocoma, Cymbopogon flexuosus, Themeda arundinacea, Chrysopogon, Desmostachya bipinnata, Dichanthium annulatum, Bothriochloa bladhii, Imperata cylindrica, Heteropogon contortus, Vetiveria zizanoides, and Imperata cylindrica which provides excellent habitat for herbivores for grazing with the protec- tion of the nearby forest areas too. Such grasslands are usually frequented by herds of elephants and deer and also makes good hunting ground for Tigers. Such grasslands are found in Rajaji National Park, Corbett National Park, Dudhwa in the sub-Hima- layan belt and Kanha National Park in Central India. The fringes of these grasslands are dominated by Chloris dolichostachya which is a shade loving forest grass.

DIRECTIONDIRECTION Main Examination 78 INSTITUTE FOR IAS EXAMINATION WET GRASSLANDS The semi-aquatic or wet grasslands are vast stretches found in the water-logged areas of the sub-Himalayan tracts, Terai, abandoned paddy fields, seasonal pools and shallow lakes, low lying areas near the sea coasts, the Phumdis of Manipur and also high altitude lakes. Phragmites australis, Arundo donax, Erianthus ravennae, Sac- charum spontaneum, Saccharum arundiaceum, and some of the tall grasses found in such wetlands where as grasses such as Paspalum distichum, Paspalum longifolium, Paspalum vaginatum, Isachne spp., Ischaemum indicum, Echinochloa crus-galli, Pani- cum repens, Eriochloa procera, and Panicum paludosum are the small grasses seen in these wetlands. Floating grasses, e.g. Hygrorhyza aristata, semi aquatic grasses, e.g. Leersia hexandra, Sacciolepis interrupta, Hymenachne acutigluma, Oryza rufipogon and several semi-aquatic species of other families e.g. Pontederiaceae, and Hydrocharitaceae are unique to such semi-aquatic habitat. The mid altitude wet- lands have Glyceria tonglensis and Paspalum paspalodes as the dominant species. The most well-known wetland grassland is the Loktat Lake in Keibul Lamjao National Park, Manipur having unique species like Zizania latifolia along with Oryza, Phragmites and other tall needs. The swampy regions of the Terai have tall clumps of Erianthus ravennae along with Typha, Saccharum and Phragmites. The wetlands of Maharashtra are DIRECTIONrich in grassland community dominated by Coix gigantea.

Threats to grassland communities The grassland communities all over the sub-continent are facing several threats owing to severe anthropogenic pressures, land filling, grazing pressure, fragmenta- tion, invasive species and to an extent climate change. Rapid urbanization and devel- opment of tourism amenities in and around natural, especially high altitude, grass- lands have increased human interference and introduction of other grass species through construction material, viz., sand transported from other areas. Species such as Saccharum spontaneum have recently shown beginning of invasion in grasslands of mid altitude tourism destinations of Uttarakhand. The grasslands of the plateaus of the Western Ghats have seen sprouting of hotels and resorts thus destroying the local ecosystem. Species such as Rhynchelytrum repens, an ornamental grass, which had invaded several grasslands surrounding Bangalore and Hyderabad including several airports has now reached Dehradun, probably by dispersal of seeds by aircrafts ply- ing all over the nation. The shola grasslands of Western Ghats have seen invasion of European bushes such as Cystisus scoparius and Ulex europaeus. Forest fires in grassland communities have played a major role in prevention of succession of grass-

DIRECTIONDIRECTION Main Examination 79 INSTITUTE FOR IAS EXAMINATION lands into woodlands. However, frequent fires have also played a negative role in change in composition of grasslands from palatable species to non-palatable spe- cies, thus making it less suitable ecosystem for herbivores. Some of the examples are Cymbopogon distans taking over several areas of Pine forest grasslands in Almora district of Uttarakhand which otherwise was dominated by Chrysopogon fulvus, Pennisetum orientale, Heteropogon contortus, Themeda anathera and Arundinella nepalensis. Another grass which has taken over in frequent fire affected areas is Imperata cylindrica. The alpine meadows have also witnessed invasion of several species of Rumex and Polygonum, especially around livestock camps. Reduced snow- fall in the treeline zone of alpine meadows have also resulted in invasion of lower altitude species into the tree line. Even grasses like Cynodon dactylon was found upto an altitude of 2900 m enroute to Kailas-Mansarovar in Pithoragarh towards the beginning of the alpine meadows of Chhialekh. Most of the semi-aquatic grasslands have witnessed rapid decline due to land filling for developmental activities. Even the abandoned rice fields are also victims of land filling and conversion of land use and agriculture systems for raising other crops such as Banana, Coconut, Rubber and vegetables.DIRECTION

DIRECTIONDIRECTION Main Examination 80 INSTITUTE FOR IAS EXAMINATION