ADVERTISEMENTS:
A natural region is one which exhibits a rough uniformity of physical features, such as relief, geomorphological history, drainage, climate, natural vegetation, animal life and soils, in relation to the adjoining regions. However, within the macro-regions, there may be’ differences in respect of these factors at the micro-level, while preserving an overall regional uniformity.
For instance, the Kashmir mountains and the northeastern hills, though part of the Himalayan chain of mountains and having similar origin, show striking differences in geology, glacial features, relief, aspect, distribution of moisture, etc. Therefore, different criteria may be required to define regions at macro and micro levels.
There are no clear-cut natural regions. This complexity is even more pronounced in a vast country like India. This is because the physical parameters, used to define a region, often overlap and their boundaries, in reality, reflect the transitional zone between two clearly marked regional units.
ADVERTISEMENTS:
The macro-regions are referred to as the regions of first order.
There are four regions of first order in India:
1. The Himalayan Mountain Complex
2. The North Indian Plain
3. The Peninsular Plateau
ADVERTISEMENTS:
4. The Islands
The micro-regions are referred to as the regions of second order, which can be further subdivided. The natural regions of second order in India are discussed below.
Regions in the Himalayas:
Moving from west to east, the Himalayas consist of a number of distinctly marked regional units.
ADVERTISEMENTS:
These units are:
1. Kashmir
2. Karakoram, Ladakh and Baltistan
3. Himachal and Kumaon.
4. Eastern Himalayas
5. Purvanchal
The level plains of the Kashmir valley are surrounded by high mountains. A temperate climate; temperate and alpine vegetation, numerous perennial streams and a great variety of forests across different mountain ranges are some of its distinguishing features. This variety is due to differences in altitude and aspect.
To the north of the Kashmir valley lie the imposing heights of Karakoram and other ranges and enclosed within them are old plateaux— Baltistan, Aksai Chin and Deosai, etc. To the north-east lies the Ladakh region, which is a cold desert with scanty natural vegetation.
The Himalayan Mountains lying to the east of the Satluj gorge are called the Himachal Himalayas, which have a different rainfall pattern and vegetation compared to the Kashmir Himalayas. The Kulu and Kangra valleys of this region- have distinct features of their own. High rainfall in this region, especially in low lying areas, is reflected in the tropical nature of vegetation.
ADVERTISEMENTS:
To further east of the Himachal Himalayas lie the Kumaon and Uttarakhand regions which have a more or less similar natural setting. From 86° E longitude onwards, there develops a sharp contrast between the eastern and western Himalayas. The deciding factor here is strong monsoon currents which cause heavy rainfall in the eastern sector. This aspect is reflected in lush green tropical wet evergreen vegetation of this region.
The Purvanchal or the Indo-Myanmarese Hills represent the southward bend of the Himalayas or the Syntaxian bend. These hills are characterised by a low altitude (generally less than 2,000 m), a lower rainfall and monsoon deciduous type of vegetation.
Regions in the Plains:
The plains are interposed between the Himalayas and the peninsular plateau and consist of the following regions:
6. Punjab Plains
7. Indo-Gangetic Divide
8. Ganga Plains
9. Gangetic Delta
10. Assam Valley
The Punjab Plains in the west are, in reality, a transitional climatic sone, having a dry climate and dry thorny forest cover. The four doabs lying in India—Ghaj, Rachna, Bist and Bari—are caused by fluctuating river courses and have different physical characteristics from the rest of the plains.
The transition zone between the Indus Plains and Yamuna is called the Lido-Gangetic Divide which is of alluvial character and represents the transition from semi-arid Punjab Plains to sub- humid Ganga valley.
The Gangetic Plains are of uniform relief formed by heavy deposition work carried out by the Ganga and its tributaries. A striking feature of this region is a gradual increase in rainfall eastwards, reflected also in the nature of vegetation and soils. This increase is related to increasing nearness of this region to the source of moisture (i.e., the Bay of Bengal).
The Ganga Delta is dotted with a typical maze of river courses and is distinguished from the rest of the plain by high humidity and high temperatures.
The Brahmaputra valley in Assam represents the eastern frontier of the north Indian plains. It is enclosed by the Himalayan foothills in the north, Purvanchal in the east and Shillong Plateau in the south. The distinct monsoon climate with a shorter than usual summer supports a thick cover of vegetation.
Regions in the Plateau:
The peninsular plateau is the most extensive geomorphological entity on the subcontinent and can be divided into the following meso-regions, or regions of the second order:
11. Thar Desert
12. Aravalli Hills
13. Central Vindhyan Uplands
14. Khandesh and Satpura-Maikal Ranges
15. Chhotanagpur Plateau
16. Meghalaya Plateau
17. Kachchh and Kathiawar
18. Gujarat Plains
19. Konkan Coast
20. Goa and Kanara Cost
21. Kerala Coastal Plain
22. Western Ghats
23. Deccan Lava Plateau
24. Karnataka Plateau
25. Wainganga and Mahanadi Basins
26. Telengana
27. Southern Hill Complex
28. Eastern Ghats
29. Orissa Delta
30. Andhra Coastal Plains and Deltas
31. Tamil Nadu
The Thar Desert lies to the west of the Aravallis beyond the north-western flank of the Plateau. This desert is a vast expanse of sand accumulated during ages of denudation under extremely hot and dry conditions. As a result, both vegetation and soil cover are very scanty.
The Aravallis separate the desert from the Vindhyan upland and Bundelkhand gneissic country lying to the east. The western slopes of the Aravallis around Udaipur are quite typically hilly, rainy and forested. North of Ajmer, the Aravallis are broken into a series of parallel ridges, which reach upto the southern margins of Delhi, and are separated by longitudinal valleys.
The central Vindhyan upland is a highly dissected region, in which a line of scarps and hill ranges run across the sub-regions of the Malwa Plateau and Bundelkhand gneissic country. These hills consist of the Vindhyan, Bhanver and Kaimur Hills. The highly dissected nature of the upland has not allowed the soil structure to develop fully; as a result, soil cover is shallow, except in narrow river basins. The vegetation varies from tropical dry deciduous to the tropical thorny types.
The Khandesh region lies in the alluvial basin of the Tapti trough, caused partially by tributary Purna, south of the Narmada scarp. The Satpura, Mahadeo and Maikal ranges, which are actually scarped plateaux, dominate the relief in this region. Khandesh lies between the Ajanta Hills and the Satpura range.
The Chhotanagpur Plateau to the east of the Son is another highly dissected upland having series of relict surfaces reflecting years of erosion. This region is characterised by varying altitude, a high rainfall, high humidity and tropical moist deciduous forest.
The Shillong Plateau in the east is, actually, an extension of the Peninsular Plateau separated by the Ganga-Brahriiaputra Plains in Bangladesh. This region has been dissected through intensive erosion over the years into a complex maze of hills. A high level of humidity and abundant sunshine support a variety of tropical wet evergreen forests.
The lava plateau of Kathiawar and the mud and salt wastes of Kachchh lie along the western flank of the Peninsular Plateau. Although many hill ranges that dot the Kathiawar peninsula are very low in height (generally 200 m), some, like the Gir Ranges, rise higher. Although dry climate and scanty deciduous vegetation dominate the region, there are variations in soil and natural vegetation because of diversity in rock formations and relief.
The Gujarat Plains represent a transition zone between the humid west coast and the arid and semi-arid Rajasthan; these plains have acquired an alluvial character because of deposition action of the Sabarmati, Mahi, Narmada and Tapti.
The Konkan Coast is a narrow, fertile plain, overlooked by highly dissected scarps of the Western Ghats. Rainfall is very high here, which makes it an intensively cultivated belt.
The Goa and Kanara Coast is generally a transition zone between Konkan and Kerala. It has a hot and humid climate with rainy seasons lengthening southwards.
The coastal plain widens in Kerala. The Kerala Coast shows a great variety in distribution of rainfall as well as vegetation. The rainfall, however, shows a decreasing trend towards the southern tip .of the peninsula.
The Western Ghat escarpments form the western edge of the Peninsular Plateau. The Ghats run continuously southwards, with occasional breaks or gaps, like those of Palghat and Shencottah, which facilitate cross-communication. The physical appearance of the Western Ghats suddenly changes near Goa. Here, the highly rugged topography of lava rocks gives way to the smoothly rounded hills composed of granites and gneisses. The western slopes of the Ghats receive heavy rainfall and support a very rich diversity of evergreen and deciduous forests.
The Deccan Plateau, which dominates the inner peninsular topography, is actually composed of layered depositions of lava which erupted during the last phases of the volcanic activity in the peninsula. The Western Ghats to the west block the main currents of the south-west monsoon, giving the Deccan Plateau region a typically rain-shadow current. In the north, the boldly rising Ajanta Hills border the Deccan Plateau. The weathering of lava layers has produced fertile black soils in the Deccan Trap region.
The Karnataka Plateau to the south of the Deccan region is characterised by a generally uniform relief, with an altitude between 450 m and 800 m. This region is composed of granites and gneisses in contrast to the Deccan region. There are variations, however, of climate, natural vegetation and soils at’local level—reflected, for instance, in two main sub-regions of Malnad and Maidan.
A series of undulating plains and basins lie to the east and north-east of the Deccan Plateau regions. The Wainganga valley and the Mahanadi basin are two main sub-regions which exhibit differences in rainfall (which is higher in upper Mahanadi basin) and vegetation (Sal fewest of Wainganga valley is replaced by teak forest in the Mahanadi basin).
The Telengana region to the south-east of the Deccan region is a low plateau which is highly denuded and dissected. The isolated relict landforms, or ‘monadrocks’, produce some diversity in the otherwise open and mature topography. The northern part has scanty vegetaiion, while the south is mainly an expanse of tropical savanna grasses.
To the south of the Palghat Gap lie the most complex hill ranges of the peninsula which include the Nilgiris, Annamalais and Palni/Cardamom group. These hills are characterised by ‘horst and graben’ topography. These hills have a rich growth of forests, particularly of teak and sandalwood.
All along the eastern coast lie discontinuous ridges which together constitute the Eastern Ghats, The Eastern Ghats are characterised by low lying hills and greater distance from the coast, in sharp contrast to the Western Ghats.
The Eastern Ghats consist of three main groups of hills:
(i) The northern hills which lie between Jamshedpur and Godavari.
(ii) The hill ranges lying between the Godavari and the Palconda range and formed mostly by the rocks of the Cudappah system.
(iii) Tamil Nadu Hills lying between Palar and Cauveri.
These hills show variations of rainfall and vegetation on account of north-south variation in rainfall and the north-south orientation of hills- parallel to the east coast of India. The northern hills are more forested than the southern ones. The Cudappah hill ranges are generally wooded but not as thickly as the northern hills. The Tamil Nadu Hills, on the other hand, have some forest growth on the eastern slopes.
The east coast of India has three main segments: the Orissa Coast, Andhra Coast and Coromandel Coast of Tamil Nadu. In Orissa, the Mahandi and Brahmani have built a wide deltaic plain, generally moist and forested in parts.
The Andhra Coastal Plain and the deltas of Godavari and Krishna show the transition between the south-west and the north-east monsoon regimes. This transition is clearly seen in the Godavari delta. The Coromandel Coast has its own rainfall regime determined by the north-eastern monsoon.