Research Journal of Earth Sciences 2 (2): 30-35, 2010 ISSN 1995-9044 © IDOSI Publications, 2010

Coastal Geomorphology and Evolution of Rameswaram Island, Tamil Nadu, India

K. Prabakaran and K. Anbarasu

Department of Geology, National College, Tiruchirapalli-620 001, Tamilnadu, India

Abstract: Rameshwaram, a strategically and socially important island in the east coast of India, is an excellent place for the study of coastal evolution during Quaternary. It has landforms like beaches, beach ridges, mudflats, raised coral terraces, lagoons, spit etc. along with l iving corals. The evolution of coastal landforms could b e clearly traced by integrating the landform distribution with available C14 dates. It is clear that sea level has played a major role in the evolution of landforms of the island. The raised terraces that has been dated to 125000 years BP indicates that the there was only fringing reefs during that period. The emerged coral during the subsequent regressive phase of the sea had been serving as place for marine sedimentation as indicated by mudflats and beach ridges of latter period. The spit is the recently formed landform of the island.

Key words: Rameshwaram % Geomorphology % Evolution % Sea level % Quaternary

INTRODUCTION Rameshwaram island of the scale 1: 50,000 were interpreted, from them the geomorphic entities were also Rameshwaram Island is located on the eastern part of mapped and the features were confirmed by field checks. Ramanathapuram district of TamilNadu (Fig. 1). It is Data was also obtained from the satellite imagery of IRS bound between the latitudes E 79°12' 30" and E 79° 27' 30" 1C and 1D and using Arc view 3.2a, Arc GIS 9.1 software. and longitudes N 9° 8' 55" and N 9° 19'. The coast of It is by compilation of data from field map, aerial photos Rameshwaram has several topographic expressions, and imagery a geomorphic map of the Rameshwaram which are the signatures of the interaction of marine and Island was prepared. The evolution of coastal landforms aeolian processes [1]. These topographic features can could be clearly traced by integrating the landform serve as ecosystems, which have components of distribution with available C14 dates. terrestrial, marine and atmospheric processes [2]. Ecosystems favor and support rich and diversified fauna Constructional and Destructional Landforms: and flora apart from serving as areas to protect the coast Constructional landforms include deltas, deltaic coastal from the activities of tides and cyclones. It is in this plains, beaches, bars, spits, reefs, dunes, mudflats and context there is a need for the scientific study of coastal many minor features. Also included in this group are geomorphic features, which can be utilized as sites for structures of organic origin. Along the coasts of warm promotion of better environmental conditions. A widely seas, algae, coral and other organisms may accumulate in varying nature of landforms and their disposition along huge quantities to form reefs, which sometimes extend the beaches and inland represents the successive phase considerable distance offshore. The position and of transgression and regression of sea level. [3]. Along development of these features are related to the stand of the eastern coast of peninsular India, narrow belts of sand the sea during their formation. Destructional or erosional dunes, coastal dunes and beach ridges are present [4]. landforms include sea cliffs, wave cut beaches, arches and caves near sea level, detached masses of rock which form Methodology: A field study involving identification and islands and sea stacks and many other forms whose mapping of the various geomorphic features present in characteristic features have developed under the the area was conducted with the help of Survey of India dominant influence of local topography, rock type and toposheets 58 O/7 and 58 O/11. The aerial photos of the structure. The Gulf of Mannar (south-eastern area)

Corresponding Author: K. Prabakaran, Department of Geology, National College, Tiruchirapalli-620 001, Tamilnadu, India. 30 Res. J. Earth Sci., 2 (2): 30-35, 2010

Fig. 1: Location map of the Study area was devoid of suspended sediments throughout the year the east coast of India in pulses to +4.5 m above LTL and whereas the Palk Bay (area North - East of the Gulf of fell back in short pulses between longer intervals of mannar) is under high suspended sediment concentration stillstand and occasional small jumps, Banerjee [8]. throughout the year and is under heavy siltation [5]. In the Rameswaram Island the beach ridges are found to present on land at about 0.5 Km from the present shore Shore Line Configuration: Regardless of the nature of line. Hence the shoreline can be classified as emergence an initial shoreline, it soon undergoes modification. type. The shoreline is relatively straight and smooth. Most initial coasts are irregular and the general tendency The Coast of Rameswaram Island can be classified in of marine gradation is to produce a more regular coast. to two sectors which is Northern and Southern sectors. The shoreline evolution was proposed by Jhonson [6] Northern coast extends from Pamban through and Valentin [7] into submerged and emerged coasts. Rameswaram town to Dhanushkodi and the Southern More complicated shorelines were regarded as coast extends from Pamban through Ramakrishnapruram submergent, in the belief that land had lowered to to Dhanushkodi. Cuspate shoreline configuration is some extent, permitting seas to drown complicated observed in the Northern coast between Peikkarumbu and topography which had been produced by weathering and Rameswaram town and in the Southern coast between erosion of surfaces exposed to the atmosphere. Smooth Pamban and Ayyanthopu. Besides these portions the coasts were regarded by many geomorphologists as shoreline is generally straight. The direction of the exhibiting shorelines of emergence, based on the shoreline configuration is generally towards North west- hypothesis that sea bottoms are flat, so that when uplifted southeast. However the shoreline is observed in the E-W to become coastal plains they formed relatively straight direction between Pamban and Peikkarumbu and north shores. east south west direction between Peikkarumbu and Rameshwaram and the flight of erosional terraces on Rameswaram town. Erosional coast is observed in the the aeolinite ridge at manappad point is that during the areas of cuspate shoreline and depositional coast is late Pleistocene highland here, relative sea level rise along observed in the areas of straight shoreline.

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Fig. 2: Coastal geomorphology around Rameswaram Island

Coastal Geomorphology: Landforms observed in the Wide beaches are observed in the Southern coast Rameswaram island are (Fig. 2) extending to a maximum of 1 Km around Natarajapuram C Beaches and in further south areas. In the Northern coast, beaches C Beach ridges and swales are generally narrow and extend only to 5 to 10 Mts. C Dunes and Sandy plains Beaches in the study area composed of fine and medium C Lagoons and Mudflats sand. In the crenulated portions of the Northern coast, C Creeks the beaches are terminated by cliffed coral reefs and C Spits Cuddalore Sandstone. Over the cliff corals and Sandstone form a terraced landform. A beach profile of Beaches: The landform that occurs through the total Rameswaram island in general exhibit the characteristics length of 72Kms of the study area without any break is (Table 1) sandy beach. The dominant wave actions with large The tail like portion of Rameswaram Island observed amount of input of sediments derived through the in the South Eastern portion is entirely made up of sandy longshore littoral currents from Southern Tamilnadu make barrier beaches. Large portion of this land is submerged the beaches as a most dynamic landform of the area. under water during high tide.

Table 1: A beach profile of Rameswaram island in general exhibit the characteristics Near shore zone Slope upto 5° Situated in front of the beach, submerged under sea water even during low tide. Fore shore zone slope 5° to 15° Situated between high tide and low tide mark. Back shore zone Flat Rarely submerged during storm surge. Aeolian activity is common.

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Beach Ridges and Swales: Beach ridges are defines as observed. The horns of all the dunes are pointing linear sandy-shelly swash deposits with intervening towards North east direction (Wind ward direction). The sandy plain occurring parallel or sub parallel to the shore height of the dunes goes up to 12 Mts. near Kariyur. The formed by periodic wave impounding action. Beach windward side is steep and leeward side is gentle in all the ridges are observed between Peikkarumbu and parabolic dunes. Migration of dunes is noticed and Pilloaikulam in the Northern coast and between Pamban artificial measures for migration have been taken up by the and Kodandaramaswami kovil in the Southern coast. Government. Besides the above said areas, dunes are Beach ridges are generally parallel to the coast and are observed in a scattered manner in places like followed in the back shore by sandy plains. Beach ridges Susaipparpattinam, Ayyanthopu and around observed in the Northern coast are discontinuous in Natarajapuram. In the study area sandy plain are nature while the beach ridges of Southern coast are observed in the central parts, almost flat terrain covered continuous in general. The height of the beach ridges with sandy plains. vary from 1M to 5 Mts. and the highest part is observed near Ayyanthopu. Lagoons and Mudflats: Lagoon can be defines as a Swales are narrow linear depression with clay and shallow body of sea water as a pond or lake, separated silty clay deposits occurring between the beach ridges. from the sea by barriers with a narrow inlet. The tail like Swales are noticed along the Southern shoreline and portion observed in the South eastern part of the island along the way to Kodandaramaswami Kovil. They are extending up to Dhanushkodi consist of two barrier absent along the Northern shoreline of the island. ridges in the North and South side and linear lagoon in between the two. The lagoon has inlet at number of Marine/Coral Terraces: In the northeast portion of the locations. Since the wave action disturbs the stagnant beaches are terminated by cliffed coral reefs and water frequently mudflat have not developed. Salt cuddalore sandstone. Over the cliff corals and sandstone marshes are also notice in few places around the lagoon. from a terraced landforms. Another lagoon is observed in the north of dune complex of Rameswaram town. Segmentation of lagoons is Dunes and Sandy Plain: Dunes are ridge or mound of observed due to the developments of ridges and dunes in loose sands formed by aeolian activity. Coastal dunes are it. The lagoon has an inlet of north of Ariyankundu. The formed when dry sands on shore are blown to the back of lagoon is encircled by mudflats. Saltmarshes are also the beach. Coastal dunes are noticed in the area east of observed. Tangachchimadam and in the area north of Rameswaram Mudflat is a flat area containing a fluid to plastic town. A large parabolic dune along with a dune complex mixture of finely divided particles of solid material silt clay is observed in the area North of Rameswaram town. The and water. They are always associated with the sheltered axis of the parabolic dune trends North east-South west. environment like lagoons, estuaries and other embayment. The limb of the dune extends from Sudukattampatti The feature is predominantly observed around the lagoon towards South west direction and culmination takes place north of Rameshwaram town. The barrier beaches around Athikadu and extends further toward North West occurring in the seaward side of the backwaters create a upto Ariyankundu. The horns are pointing towards North sheltered environment, which has favored the east direction. It has a length of 6 Kms and width ranges development of mudflat. In the southwest nearer to from 0.5 Km near Kudiyiruppu. The height of the dune Pamban and Ayyanthopu mudflat is formed around raises upto 6 Mts. near Kalugupuli. The dune complex creeks. observed around Olakude, Erakadu, Mangadu, Sambi, Gandhamanaparvatam covers an area of 8 to 10 Sq.Kms. Creeks: Tidal creeks are inlets, through which water The height of the individual dunes varies from 1M to 10 flows to and from a lagoon or other backwaters Mts. The highest dune is observed near Gandhamana, during high and low tides respectively. Creeks are over which the temple Ramarpatham is located. The wind observed in southwest part near Pamban and ward side of the parabolic dune and all the dunes of dune Ayyanthopu. Near Pamban, the creek is of ‘Z’ shaped complex exhibits steep slope and leeward side exhibits in nature found nearer to the spit having a length of gentle slope. The horns of the parabolic are pointing 1 km approximately. They are also noticed in the linear towards windward side. In the area East of portion of the island through which the seawater enters Tangachchimadam numbers of parabolic dunes are into the lagoon.

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Table 2: Radiometric dates of Coastal Quaternary deposits Sl. No. Reference Site Specifications Laboratory No. Age Remarks 1 Bruckner [11] Rameshwaram Coral reef, noth --- 112 ka (ESR) Last interglacial side of the Island, maximum Porites.sp. upto +2.5m above 2 Stoddart and Rameshwaram Porites.sp from GAK-3187 4020+/-160 --- Gopinadha Pillai [12] the raised coral yr. BP. reef at Pamban (14C age) 3 Loveson [13] Ariyankundu Coral +0.55 m 30/248/C5 5440+/- 60 Middle Holocene above MSL yr. BP. (14C age) transgression

Spits: Spits are beaches which leave the main shoreline, regression low. Recent marine processes construct Barrier usually at estuary mouths or bays and project into deeper bars with enclosed lagoon at south eastern portion of the water before terminating. When a shoreline following Island. by a littoral current turns abruptly landwards, as at the entrance of a bay, the current dose not turn with it but REFERENCES holds its course, the supply of shore drift brought to this point by the littoral current dose not cease and the 1. Loveson, V.J. and G.V. Rajamanickam, 1988. Coastal necessary result is accumulation. In study area the spit is Geomorphology of the southern Tamilnadu, India. observed near Pamban and Ayyanthopu. The projection Proc. Natl. Symp. Remote Sensing in Land of spit near Pamban is in southern direction and in Transformation and Management, Hyderabad, (Eds.) Ayyanthopu in south west direction. The tail like portion S.K.Bhan and V.K. Jha. of Rameswaram Island itself is a spit that has been formed 2. Tooley, M.J., 1974. Recent evolution of Mangroves by the movement of littoral current between Rameswaram vegetation in the Cauvery delta: A palynological and Srilanka. study. Jour. Mar. Biol. Ass. India,.29: (1- 2). 3. Karikalan. R., K. Anbarasu. and G. Victor Coastal Evolution: A proper interpretation of coastal Rajamanickam, 2001. Coastal Geomorphology of landforms will generate the details of the processes and Portnova region, south Arcot district, Tamilnadu. materials that were involved in the genesis of landforms, Indian J. Geomorphol., 6(1, 2): 157-169. which in turn will help in understanding the coastal 4. Alexander kunz, Manfred Frechen, Ramachandran evolution. C14 data of coastal samples of Rameswaram Ramesh and Brigitte Urban, 2009 Luminescence Island is obtained by different researchers were collected dating of late Holocene dunes showing remnants of and these data were used for understanding the evolution early settlement in Cuddalore and evidence of of coastal landforms of Rameswaram (Table 2). monsoon activity in south east India. Quaternary Rajamanickam and Loveson [10], based on C14 results International, Elsevier, Article in Press, Doi: of the coral samples collected around Rameswaram area 10.1016 : 1-15. have inferred that transgression around 5000 years BP 5. Rajawat A.S. and Mukesh Gupta, Yaswant pradhan, must have resulted in Ariyankundu Coral Terrace. Thomas kutty. A.V and Shailesh Nayak. 2005. Quaternary sea level change aeolion process and resent Coastal processes along the Indian coast - case marine process are found to be responsible for the origin studies based on synergistic use of IRS-P4 OCM and of general landscape of Rameswaram. IRS-1C/1D data. Indian J. Marine Sci., 34(4): 459-472. 6. Johnson, D.W., 1919. Shore process and Shoreline CONCLUSION development. Wiley, New York, pp: 584. 7. Valentin, H., 1952. Die kusten der Erde. Petermanns In the origin of landforms the following sequence of Geog. miti. Erganzung sheft, pp: 246. events are inferred. Quaternary sea level rise had reached 8. Banerjee P.K., 2000. Holocene and late Pleistocene a level high above the present marine /coral terraces. relative sea level fluctuations along the east coast of Marine/coral terraces were formed during the Lowering of India. International J. Marne Geology, Elseiver, sea level. The dunes were formed subsequent to the 167: 243-260.

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9. Rajamanickam G.V. and V.J. Lovson, 1990. 11. Bruckner Helmet, 1988. Indicators for formerly Result of Radiocarbon dating from some beach Higher sea-levels along the east coast of India and terraces around Rameshwaram Island, sea level on the Andaman Islands. Hamburger Geographische variation and its impact on coastal environment, studien, Heft, 44: 47-72. published by Tamil University, Thanjavur. 12. Loveson, V.J. and G.V. Rajamanickam, 1990. Results pp: 389-396. of Radiocarbon dating from some beach terraces 10. Stoddart, D.R. and C.S. Gopinatha Pillai, 1972. Raised around Rameshwaram Island, Tamilnadu. In: reefs of Ramanathapuram, South India. Trans. Inst. Sea-level variation and its impact on coastal of British Geographers. Pub., No.56. environment, Eds. G. Victor Rajamanickam, Pub. Tamil University, Thanjavur, pp: 389-396.

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