Geodiversity, Geogrphical Heritage and Geoparks in India

Geodiversity, Geogrphical Heritage and Geoparks In India R.B. Singh and Subhash Anand University of Delhi, Delhi, INDIA 1 Introduction The development of all biotic and abiotic resources relies on bedrock, soil, landform and related systems and processes. The diversity of these systems and processes de- termines the richness of biodiversity. The geological history of India started with geological evolution about 4.57 billion years ago. Indian geological formations consist of the Deccan trap, the Gondwana and the Vindhyan and those that originated in Pleistocene, Tertiary and Pre-Cambrian periods. Conventionally, the country is di- vided into three physiographic regions viz., the Himalaya and associated mountain chain (5,00,000 sq. km.), the Indus-Ganga-Brahmaputra plains (7,00,000 sq. km.) and the Peninsular plateau (19,00,000 sq. km.) including the coasts and the islands. The world’s 14 highest peaks and few large rivers of the world are located in the Himalaya. The Indus-Ganga-Brahmaputra plains located in the northern part of the country, extends for 3,200 km. from the river Indus in the west to Brahmaputra in the east. Its width varies between 150-300 km. The senile peninsular plateau in the south is trian- gular in shape and has some of the oldest mountains of the world with elevation var- ying between 600 and 800 meters. The Islands include the Lakshwadeep (36 coral Islands), the Andaman (200 Islands) and Nicobar (19 Islands) (Singh, 2012). Out of the total geographical area of the country, 2,386,000 sq. km. (Himalayan and Penin- sula region) is made up of hard rock. Geodiversity is defined as the variety of geological features, including rocks, minerals, fossils, soils, geological units and landscapes, which are the result of the Earth’s evolution and history (Panizza, 2001). According to Brocx and Semeniuk (2007), geoheritage is a concept concerned with the preservation of features with importance to Earth science, such as landforms, natural and artificial exposures of rocks, and sites where geological features can be examined. A geosite is a locality that constitutes part of the geoheritage of a territory. UNESCO in its Geoparks International Network of Geoparks programme describes a geopark as a territory encompassing one or more sites of scientific importance, not only for geological reasons but also by virtue of its archaeological, ecological or cultural value. Preserving the rocks beneath our feet is necessary for earth science and for education; it is a vital part of nature conservation. Geoparks and geosites can become our modern earth science clubs if maintained and Author: R.B. Singh,Department of Geography, Delhi School of Economics, University of Delhi, Delhi – 110007, INDIA; [email protected] Subhash Anand. Department of Geography, Swami Shraddhanand College, University of Delhi, Delhi – 110036, INDIA; [email protected] www.igu-cog.org R.B. Singh, et al.: Geodiversity, Geogrphical Heritage and Geoparks In India 11 manned with urgent top priority dedication (Ahluwalia, 2006). 2 State of Geodiversity in India Geodiversity is the natural range of geological (rocks, minerals, fossils), geomor- phological (landform, processes) and soil features. It includes their assemblages, rela- tionships, properties, interpretations and system (Gray, 2004). India is both a mega-biological diverse country with outstanding geodiversity (Figure 1) and this diversity helps to define its fifteen bioregions. India occupies just 2.4 per cent of the Earth’s land surface and has 7 per cent of the mammals, 12.6 per cent birds, 6.2 per cent reptiles, 4.4 per cent amphibians, 11.7 per cent fishes and 6 per cent flowing plants of the world (Singh, 2012). The remarkable geodiversity that includes Hima- laya, Thar Desert, Deccan Plateau, Sunderbans and Lakshdweep coral reef islands. Outstanding geographical heritage such as these iconic features are celebrated as part of India’s national identity. Many are inscribed World Heritage Sites and many are included on India’s National Heritage List. Figure 1 Geological map of India Source: Geological Survey of India, 2001 2.1 Mountain The mountains of India are broadly classified into two types: extra-peninsular or Hi- malaya and peninsular (Wadia, 1919). The geological structure and age of Himalaya fall into three broad stratigraphical belts viz. The Northern or Tibetan zone, The Cen- tral or Himalayan zone and The Outer or Sub-Himalayan zone. The first zone lies behind the line of highest elevation and is composed of continuous series of highly 12 INTERNATIONAL JOURNAL OF GEOHERITAGE fossiliferous marine sedimentary rocks, ranging in the age from the earliest Palaeo- zoic to the Eocene age. The central zone comprises mostly of crystalline and metamorphic rocks - granites, gneisses with unfossiliferous sedimentary deposits of very ancient age. The third zone corresponding to the Shivalik range is composed entirely of tertiary, and principally of upper tertiary, sedimentary river deposits (Figure 2). High relief, snow-capped summit, deeply dissected topography, antecedent drainage, complex geological structure and rich temperate floras in the sub-tropical latitudes give a distinct character to the Himalayan mountain ranges. The Eastern Himalaya covers an area of 67,500 sq. km. with many piedmont plateaus present in this area. Geologically, this area is characterized by a fault scarp with well foliated schist abut- ting against gneissic rocks and locally defining the lineament of artisans springs (Nag & Sen Gupta, 1992). Figure 2 Geodiversity in Himalaya - (a) Horizontal layering in Himalaya; (b) Loess structure in the Lahul and Spiti, Himalaya The most important ranges of Peninsula are: The Aravalli mountains, the Vindhyas, Satpuras, the Western Ghats and irregular broken and discontinuous chain of eleva- tions known as the Eastern ghats. Aravallis were a prominent feature of the old Plaeozoic and Mesozoic era and extended as a chain of lofty mountains from the Deccan to possibly beyond the northern limit of India. In present time, they are just deeply eroded remnants laid bare by repeated cycles of erosion. The Vindhyas are for the most part composed of horizontally bedded sedimentary rocks of ancient age. The Vindhyas and Satpuras form the backbone of central India. The western and eastern parts of Satpuras are formed of Cretaceous basalts; the central part is composed, in addition to a capping of the traps, of a core of granitoid and metamorphic rocks over- laid by Mesozoic sandstones. The Western Ghats, as the name Ghat denotes, are, down to Malabar, steep-sided, terraced, flat toped hills or cliffs facing the Arabian sea-coast running parallel to it. The horizontally bedded lavas of which they are wholly composed have, on weathering, given rise to a characteristic "landing stair" aspect. Beyond Malabar they are composed of very ancient massive crystalline rocks, and not of horizontal layers of lava-flows. The broken and discontinuous line of mountainous country, the eastern facing the Bay of Bengal, and known as the Eastern Ghats, has neither the unity of structure nor of characteristic of a mountain-chain. Among the remaining, but less important, hill ranges of the Peninsula are the trap-built Rajmahal hills of western Bengal, the Nallamalai hills near Cuddapah, built of gneissose granite, and the gneissic plateau of Shevaroys and Pachamalai, south-west of Madras. R.B. Singh, et al.: Geodiversity, Geogrphical Heritage and Geoparks In India 13 2.2 Desert India has a vast desert comprising of about 390,000 hectare of land. The deserts of India are diverse in nature and vary from hot sandy desert in the west to cold desert in the north. The Indian deserts can be classified into following three forms. 2.2.1 The Sandy Desert of Rajasthan The Thar desert is the western most fringe of the Deccan mainland forming shield area of the Indian sub-continent during pre-Cambrian times. On the west rock exposures are less frequent but known to include Malani igneous rocks, Vindhya, Marine Jurassics and Eocene rocks. It is understood that this area was under sea during Juras- sic times which is evident from fossils recovered in the Jaisalmer district of Rajasthan (Figure 3). Highly fossiliferous marine deposits over Talchir beds show that species lived in more or less isolated arms of large sea spread over the Himalayan region (Chauhan & Sharma, 2008). Figure 3 Desert diversity in Western Rajasthan - (a) Sand dunes in Thar desert and (b) Cultivating sand dune 2.2.2 The Cold Mountain Desert of Trans Himalaya Cold deserts in India have been formed primarily due to the rain-shadow effect of the towering Himalayan mountain wall and its offshoot ranges which run in an arcuate shape from the Indus gap in the north-west to the Brahmaputra gap in the north-east. There are two physiographic classes of cold deserts in India viz. Trans-Himalaya and Inner dry valleys. The cold desert extends like flat tableland towards the north. High mountain ranges like the Karakoram and Zaskar dissect the cold deserts. Broad sandy river terraces have been formed by the larger rivers such as the Indus, in the core zone of the cold desert. The inner dry valleys are formed by high mountains on all sides. Often, they may be in the form of steep gorges with rivers draining their bottoms (Negi, 2002). 2.2.3 The White Salt Desert of Kutch The Kutch landscape comprises an array of tectonogenic geomorphic elements in the form of uplifts and residual depressions. Elevated landforms are occupied by Meso- zoic and Tertiary rocks, whereas the residual depressions or low-lying regions between the uplifts consist of Quaternary sediment successions marked alluvial river terraces in the rocky mainland and the mud-flats and salt pans in the Great and Little Ranns and Banni Plains. The general forms of the uplifts are marked by domes and asymmetric anticlines.

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