01_Coffee Table Book on Lakshdweep Island of India

© GEOLOGICAL SURVEY OF INDIA (2014) Write up and compilation Satish Kumar, Superintending Geologist Kailash Singh, Geologist Designing by Kailash Singh, Geologist Photography Satish Kumar, Superintending Geologist Mr. Sikander Hussain, diver cum underwater photographer Internet Supervision Deputy Director General Geological Survey of India Marine and Coastal Survey Division Mangalore

Lakshadweep (means a hundred thousand islands) islands lie scattered in the Arabian Sea FOREWORD about 220 – 450 km from the western coast of Indian sub-continent, mainly off the Kerala region. They are the only coral islands of our country. It is the tiniest Union Territory (U.T.) of India. The Union Territory was formed in 1956 and was named Lakshadweep in 1973. Lakshadweep Islands are a string of islands, which form the northern most part of the Laccadive – Chagos Ridge aligned in a north – south direction. Lakshadweep Archipelago comprises of 12 atolls, 3 reefs and 5 submerged banks. The individual islands project like spikes all along the ridge, with coral and submerged reefs. The Lakshadweep Islands have a vast expanse of the blue sea with precious heritage of ecol- ogy and environment. These Islands are rich in marine wealth and an abode of coastal and marine bio-diversity with pristine Coral Reef Ecosystem which supports variety of flora and fauna. Halimeda is the most important consistuent in the lagoon and most prolific sediment contributor. The sediments in the atolls are pure skeletal carbonate sands with very low amount of silica, alumina and Fe2O3. The Hypothesis for formation and growth of islands varies from a volcanic hot spot theory to tectonically dissected differential subsidence block for the formation of isolated islands and banks. Lakshadweep Islands are one of the low-lying small group of islands in the world and accord- ingly face the risks of, inundation of seawater due to storm surges as well as due to Tsunami waves. The low level of Lakshadweep islands also make them vulnerable to sea level rise and its consequent impact which is a slow and long-term process. As such, the foremost future threat to these island chains is potential global climate change. Assessment of vulnerability of Lakshadweep Islands to both the natural and man-made haz- ards becomes multifold mainly due to their remoteness and geographical isolation from the mainland. The small size of the islands also acts as a barrier leading to high levels of vulnerability. Tourism is an important source of income for the islands population, and Lakshadweep is be- coming increasing popular with both domestic and foreign tourist. Tourism related infrastructure de- velopment may also affect carrying capacity of these islands leading to pressure on natural re- sources. Director General Geological Survey of India

Lakshadweep (means a hundred thousand islands) islands lie scattered in the Arabian Sea about PREFACE 220 – 450 km from the western coast of Indian sub-continent, mainly off the Kerala region. They are the only coral islands of our country. It is the tiniest Union Territory (U.T.) of India. The Union Territory was formed in 1956 and was named Lakshadweep in 1973. Lakshadweep Islands are a string of islands, which form the northern most part of the Laccadive – Chagos Ridge aligned in a north – south direction. Lak- shadweep Archipelago comprises of 12 atolls, 3 reefs and 5 submerged banks. The individual islands pro- ject like spikes all along the ridge, with coral and submerged reefs. The Lakshadweep Islands have a vast expanse of the blue sea with precious heritage of ecology and environment. These Islands are rich in marine wealth and an abode of coastal and marine bio- diversity with pristine Coral Reef Ecosystem which supports variety of flora and fauna. Halimeda is the most important consistuent in the lagoon and most prolific sediment contributor. The sediments in the atolls are pure skeletal carbonate sands with very low amount of silica, alumina and Fe2O3. The Hypothesis for formation and growth of islands varies from a volcanic hot spot theory to tec- tonically dissected differential subsidence block for the formation of isolated islands and banks. Lakshadweep Islands are one of the low-lying small group of islands in the world and accordingly face the risks of, inundation of seawater due to storm surges as well as due to Tsunami waves. The low level of Lakshadweep islands also make them vulnerable to sea level rise and its consequent impact which is a slow and long-term process. As such, the foremost future threat to these island chains is potential global climate change. Assessment of vulnerability of Lakshadweep Islands to both the natural and man-made hazards becomes multifold mainly due to their remoteness and geographical isolation from the mainland. The small size of the islands also acts as a barrier leading to high levels of vulnerability. Tourism is an important source of income for the islands population, and Lakshadweep is becom- ing increasing popular with both domestic and foreign tourist. Tourism related infrastructure develop- ment may also affect carrying capacity of these islands leading to pressure on natural resources. S. Kannan Deputy Director General Geological Survey of India Marine and Coastal Survey Division Mangalore



1 www.portal.gsi.gov.in Marine and Coastal Survey Division

The Lakshadweep islands lie scattered in the Arabian Sea about 200 – 500 km from the western coast of Indian sub-continent, mainly off the Kerala re- gion. It is the tiniest Union Territory (UT) of India. Lakshadweep the only coral archipelago of our country, are a group of coral atolls enclosing lagoons, submerged reefs and banks. It is described as the ‘coral paradise’ of India. Geographically, the islands lie between 08o and 14o North latitude and 71o and 74o East longitude. Kavaratti is the capital and Administrative Headquarter of the U.T. The Union Territory was formed in 1956 and was named Lakshadweep in 1973. 2 Marine and Coastal Survey Division www.portal.gsi.gov.in

Lakshadweep (means a hundred thousand islands) Group of Islands comprises of 36 islands having an area of 32 sq. km. of which 2.40 sq. km. is uninhabited. Of the 36 islands only eleven are inhabited islands, 16 uninhabited islands, four newly formed islets and 5 submerged reefs. 3 www.portal.gsi.gov.in Marine and Coastal Survey Division

These islands have about EEZ is 400,000 sq. km., 20,000 sq. km of territorial waters. The Atolls reefs and submerged banks total 4200 sq. km. The continental shelf is very narrow and occupies an area of around 7770 sq. km. Length of coastline of Lakshadweep is 132 km. This spectacular Island group is believed to have been discovered by shipwrecked sailors during the reign of Cherman Perumal, the legendary king of Kerala in the 4th century A.D. Before moving into the hands of the British, Tipu Sultan held sway in the Islands after defeating the oppressive rulers of Arackal. 4 Marine and Coastal Survey Division www.portal.gsi.gov.in

The inhabited islands are (Agatti, Amini, Andrott, Bitra, Chetlat, Kadmat, Kalpeni, Kavaratti, Kiltan and Minicoy) and one island (Bangaram) has a tourist resort only. Other islands are small and exist as satellites of the inhabited islands. www.portal.gsi.gov.in Marine and Coastal Survey Division 5

Inhabitated Islands except for Suheli Par 6 Marine and Coastal Survey Division www.portal.gsi.gov.in

ANDROTT is the largest island with an area of 4.84 sq. km. Androth is the nearest island to mainland of India and the only island that does not have a lagoon. MINICOY is the southernmost islands and has the oldest lighthouse which was built in 1885. It is separated from Maldives by the Eight degree channel. CHETLAT is the northern most inhabited island and is 378 km from Minicoy. BITRA is the smallest inhabited island with an area of 0.10 sq. km. but perhaps has the most magnificent and the largest lagoon. All the islands lie north to south, excepting Androth and Tinnakara that lie MINICOY is the southernmost islands and has the oldest lighthouse which was built in 1885. It is separated from Maldives by the Eight degree channel. CHETLAT is the northern most inhabited island 7 www.portal.gsi.gov.in Marine and Coastal Survey Division

There are three submerged coralline banks in the northern most part of Lakshadweep Archipelago occupying an area of about 3450 sq. km. They are 90 km north of northern most Chet- lat Island. They are Bassas de Pedro, Sesostris, Cora Divh. All the three banks are close to each other and morphologically ( shape, size and surface undulations) separate at the top and coalesce into a single common base around 1200 m water depth. The top surface is generally flat and covered with medium to coarse sands made up of corals, shell, shell fragments, microforams, living corals and cemented corals (with plenty of ooids) of all size (mainly pebble to cobble) and shape. The carbonate (CaO >50%) is biogenic and devoid of terrigenous sediment. Also an inter-island sand bank occur between Amini – Pitti having an area of about 155 sq. km. Elikalpeni banks which is situated north east of Andrott Island have an area of 96 sq. km. and there are the nearest to the mainland. 8 Marine and Coastal Survey Division www.portal.gsi.gov.in

The Lakshadweep Islands are a string of islands, which form the northern most part of the Laccadive–Chagos Ridge (1100 km long) aligned in a north–south direction. The Lakshadweep ridge extends from 08o 00' 00”N latitude in the south to 14 o 40' 00”N latitude in the north for about 800 km. The width of the ridge varies from 60 km along 8o 30' 00”N latitude to 180 km along 13o 00’ 00”N latitude. The various atolls rise from a depth ranging from 1500 to 4000 m. www.portal.gsi.gov.in Marine and Coastal Survey Division 9

Lakshadweep Archipelago comprises of 12 atolls, 3 reefs and 5 submerged banks. The individual islands project like spikes with an approximate slope gradient of 15o to 20o. All along the ridge there are innumerable spikes like projections, with coral reefs, submerged reefs and islands. Some of them are exposed on surface of the sea and while others below the sea level at different water depths. 10 Marine and Coastal Survey Division www.portal.gsi.gov.in

Lakshadweep Islands are coral islands in the Arabian Sea. Several theories are available in the literature on the formation of these atolls. From fringing reefs surrounding volcanic islands, during subsidence, grew up gradually to develop ring shaped barrier reefs and, as subsidence continued, eventually became centre island free ring reefs. All the Laccadive islands are remains of eroded atolls raised only a few feet above the sea level and formed entirely of coral rock and coral sand. Another school of thought believes that Maldives and Laccadives were formed on a large bank which was a part of an ancient land that completely sank. Some of the islands are remnants of mountains that existed in the sunken land. In general confirmity with the geological history of the Indian Ocean reefs, it may be stated that the reefs of Lakshadweep were built in Tertiary and Quaternary eras on volcanic structures and the present day surface features of the reefs are the results of erosional and depositional consequence of Pleistocene and Holocene sea level changes. www.portal.gsi.gov.in Marine and Coastal Survey Division 11

All islands in Lakshadweep except for a few, is enclosed by a lagoon and fringed by well-developed coral reef on the western margin and a narrow rocky beach on the eastern side. The shape of islands varies from crescent to linear to oval in shapes, trending NNE-SSW except for a few. The Islands are more or less flat, monotonous in nature except for the prominent well-developed sand dunes in some of them. Ground elevation varies from 0.1 to 7.0m. There are no hills and rivers in all the islands of Lakshadweep. The island is fully covered by coconut vegetation and human dwellings. The entire island is composed of assorted mixture of white carbonate sands composed of coral remains and Halimeda as major constituents. 12 Marine and Coastal Survey Division www.portal.gsi.gov.in

Each island is enclosed by lagoon and fringed by coral reefs on the western side which separates it from incoming swells of the outer sea by the wall of a reef made up of massive coral boulders and live corals. The lagoon is completely locked on all sides by the reef margin and having passages (P) to the sea at a number of places. A common feature of all islands is that a shallow lagoon exists invariably on their western side except Bangaram and Cheriyakara, which lie in the center of the lagoon. On Bitra, the island is on the northern edge of the lagoon. Andrott has no lagoon. www.portal.gsi.gov.in 13 Marine and Coastal Survey Division

Beach rock is exposed The lagoonal side beach on the western side during low tide along the of the island is made up of fully white sparkling, waterfront on both sides of white carbonate sands and Beach rock. The beaches the island. They are dull are broader with gentle slopes. white to dark in colour, fairly Marine and Coastal Survey Division compact, consist of calcarenites composed of reef detritus of corals, shells of gastropods, bivalves, halimeda and others. They contain mainly aragonite. The outcrops in general have a hummocky surface. 14 www.portal.gsi.gov.in

Sand dunes are present in some of the islands. Sand dunes are seen all along the Kadmat Island from north to south along the lagoon shore. They are well developed and very prominent and vary in height from less than 1 to 3 m. Beach rock conglomerate are mainly composed of cobble/ boulders of coral reefs (C) and other biogenic ingredients in a fine matrix. www.portal.gsi.gov.in Beach rock conglomerate 15 Marine and Coastal Survey Division

The eastern side of the island represents a narrow, prominent boulder zone of reef flats in the form of a rampart or pavement formed by storms. They are often referred as storm beach in most of the literature. They are composed mainly of shingle/ rubble spreads of coral reef detritus. Wave-cut terraces of coralline limestone and white carbonate sands/ beach rock are seen on the beach. Storm beaches are present in some of the islands like Kadmat, Minicoy, Chetlat, Kiltan. Beach morphometric units are mostly absent and obliterated due to erosional/accrectional activities. The beaches on this side are not continuous in nature as they are either absent or very narrow as they mingle with the shingle spreads of reef. 16 Rubble spreads and boulders of coralline rocks exposed at low tide www.portal.gsi.gov.in Marine and Coastal Survey Division

In the inhabited islands - lagoon area varies from 1.50 sq.km. in Amini to 45.61 sq.km. in Bitra Island. Among the inhabited islands - Bitra has the biggest lagoon. Among the uninhabited islands - Tinnakara Island’s lagoon has an area of 125.21 sq.km. Water depth in the lagoons vary from less than 1m to >50m. The placid waters of the lagoons are home for an exotic and kaleidoscopic underwater marine life. www.portal.gsi.gov.in Marine and Coastal Survey Division 17

The carbonate is biogenic and devoid of terrigenous sediment. The sediments are pure carbonate sands with very low amount of silica, alumina and Fe2O3. Coral debris on lagoon floor The only impurity is MgO, which is present in minor amounts. This is particularly high near the reef margins due to contributions from calcareous algae. 18 Marine and Coastal Survey Division www.portal.gsi.gov.in

The commonest corals are Acropora sp., Porires sp., Diploastrea sp., Goniastrea sp. and Lobophyllia sp. www.portal.gsi.gov.in Staghorn Corals (Genus: Acropora) 19 Marine and Coastal Survey Division

20 Corals (Porite variety) www.portal.gsi.gov.in Marine and Coastal Survey Division

www.portal.gsi.gov.in Table Corals (Genus: Acropora) 21 Marine and Coastal Survey Division

The carbonate sands in the lagoon are products of coral remains, Halimeda and others. Halimeda is one of the major constituents of the lagoon sediment world over. Halimeda is a genus of macroscopic, calcareous, green algae belonging to the order Caulerpales (phylum Chlorophyta). A typical Halimeda algae is a flexible string of flattened leaf-like structures. Calcareous algae deposit calcium carbonate in their tissues. When the algae dies, the calcium carbonate is left as sediment in lagoons and reefs. In fact most of the white beach sands we see in the tropics is made from dead skeletons of these algae. It is the most prolific sediment contributor in the atolls world over. In an average, Halimeda constitute 40% and corals 30% in the lagoon. 22 Halimeda www.portal.gsi.gov.in Marine and Coastal Survey Division

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LAGOON AGATTI Kalpitti Islet Island Lagoon Lagoon area Name of Island Area (sq.km.) Length x Width Length (km) Width maximum (sq.km) maximum (km) (km) AGATTI 17.50 Kalpitti Islet 3.84 7.75 x 0.80 8.10 3.20 - 0.07 - -- www.portal.gsi.gov.in 24 Marine and Coastal Survey Division

Western Lagoon KADMAT Eastern Lagoon LONGEST ISLAND WITH TWO LAGOONS Island Lagoon Lagoon area (sq.km) Name of Island Area (sq.km.) Length x Width Length (km) Width maximum 37.50 KADMAT maximum (km) (km) 3.20 9.00 x 0.50 10.20 1.20 25 Marine and Coastal Survey Division www.portal.gsi.gov.in

LAGOON CHETLAT Island Lagoon Lagoon area (sq.km) Name of Island Area (sq.km.) Length x Width Length (km) Width maximum 01.60 CHETLAT maximum (km) (km) 1.40 2.50 x 0.5 02.20 0.75 www.portal.gsi.gov.in 26 Marine and Coastal Survey Division

LAGOON BITRA Island Lagoon Lagoon area (sq.km) Name of Island Area (sq.km.) Length x Width Length (km) Width maximum 45.61 BITRA maximum (km) (km) 0.10 1.50 x 3.0 11.50 4.70 27 Marine and Coastal Survey Division www.portal.gsi.gov.in

LAGOON AMINI Island Lagoon Lagoon area (sq.km) Name of Island Area (sq.km.) Length x Width Length (km) Width maximum 01.50 AMINI maximum (km) (km) 2.62 3.00 x 1.5 03.50 0.10 to 0.20 www.portal.gsi.gov.in 28 Marine and Coastal Survey Division

Parali Islets I, II & III Tinnakkara BANGARAM LAGOON Island Lagoon Lagoon area Name of Island Area (sq.km.) Length x Width Length (km) Width maximum (sq.km) maximum (km) (km) BANGARAM 28.06 Tinnakkara 1.00 1.50 x 0.8 07.80 3.80 125.21 Parali Islets I,II,III 0.42 -- 0.02/0.02/0.01 29 Marine and Coastal Survey Division www.portal.gsi.gov.in

Parali Islets Cheriyam Tilakkam Islets LAGOON KALPENI Island Lagoon Lagoon area Name of Island Area (sq.km.) Length x Width Length (km) Width maximum (sq.km) maximum (km) (km) KALPENI 25.60 Cheriyam 2.79 5.00 x 1.3 10.50 4.30 Tilakkam Islets - Parali Islets 0.46 2.80 x 0.3 -- www.portal.gsi.gov.in 30 Marine and Coastal Survey Division

A NDROTT LARGEST INHABITATED ISLAND WITHOUT LAGOON Island Lagoon Lagoon area (sq.km) Name of Island Area (sq.km.) Length x Width Length (km) Width maximum ANDROTT maximum (km) (km) 4.90 4.5 x 1.5 NO LAGOON 31 Marine and Coastal Survey Division www.portal.gsi.gov.in

LAGOON KAVARATTI Island Lagoon Lagoon area (sq.km) Name of Island Area (sq.km.) Length x Width Length (km) Width maximum 04.96 KAVARATTI maximum (km) (km) 4.22 5.00 x 1.5 04.50 0.80 www.portal.gsi.gov.in 32 Marine and Coastal Survey Division

VIRINGILI ISLET LAGOON MI NICOY Island Lagoon Lagoon area Name of Island Area (sq.km.) Length x Width Length (km) Width maximum (sq.km) maximum (km) (km) MINICOY 30.60 Viringili Islet 4.80 10.6 x 1.0 09.00 4.20 - 0.02 - -- 33 Marine and Coastal Survey Division www.portal.gsi.gov.in