St. Mary's Islands

St. Mary's Islands Thonsepar
Island
St. Mary's Islands Location in Karnataka, India
Coordinates: 13°22′46″N 74°40′23″E / 13.3795°N 74.6730°E / 13.3795; 74.6730
Country	India
State	Karnataka
District	Udupi
Elevation	10 m (33 ft)
Population
• Total	0
Languages
• Official	Kannada
Time zone	UTC+5:30 (IST)
Four Islands -Coconut Island, the North Island, the Daryabahadurgarh Island and the South Island

St. Mary's Islands, also locally known as Thonsepar (literally "Coconut Islands"), a set of four small uninhabited touristy islands in the Arabian Sea off the coast of Malpe in Udupi district of Karnataka state in India, known for their distinctive geological formation of columnar rhyolitic lava,^[1] which are one of the four National Geological Monuments of India located in Karnataka state out of total 34 such monuments in India proscribed by the Geological Survey of India for their protection, maintenance, promotion and enhancement of geotourism.^[2][3][4][5]

Scientific studies indicate that the basalt of the St. Mary's Islands was formed by sub-aerial subvolcanic activity, because at that time Madagascar was attached to India. The rifting of Madagascar took place around 88 million years ago.^[6]

With the discovery of the sea route to India in 1498, Vasco da Gama landed at St Mary's Islands, at the end of the voyage from the Kingdom of Portugal. Da Gama fixed a cross and named one of these islands O Padrão de Santa Maria in Portuguese, as a dedication to St Mary, the virgin-mother of Jesus Christ, before proceeding to Calicut (Kozhikode) in the Malabar region, the present-day Kerala.^[7][8]

Out of the four islands, the northernmost island has a basaltic rock formation in a hexagonal form, the only one of its type in India such as Malpe and others. The island covers an area which is about 500 m (1,640.4 ft) in length with a width of 100 m (328.1 ft). It has prominent coconut trees, its cover reflecting an azure south sea colour, and hence the island is also called Coconut Island. There is no habitation on the islands.^[9][10]

The north–south aligned islands form a non-continuous chain. The four largest islands are Coconut Island, North Island, Daryabahadurgarh Island and South Island.^[11]

The islands are generally aligned parallel to the coast line, which provide clues to the phenomenon of uplift of the west coast of India. The islands' terraces and elevated beach deposits along with the tide gauge data at the dead oyster beach in Suratkal (further south of the islands) have been deduced as proof of the reported fall in sea level of about 1 mm/per year.^[6]

The highest elevation at Coconut Island, which has generated interest among geologists and tourists, is about 10 m (32.8 ft) above msl with surrounding areas in the form of platforms in the elevation range of +6 m (19.7 ft), +3 m (9.8 ft), +1.5 m (4.9 ft) and + 0 m which are stated to have been formed by wave action pointing to an "episodic sea level rise or fall of land".^[6]

The columnar basaltic lava found in these Islands, which is very well developed in the basalts of Deccan Traps, exhibit an imposing range of hexagonal shaped or multi-faced (polygonal) columns split into a horizontal mosaic. In geological terms these are called "columnar joints".^[1] The lava rocks form regular five, six or seven-sided pillars, called "laminar lava", and are found in varying heights in all the islands; the tallest of the columns is about 6 m (20 ft). Considering the importance and rarity of such an occurrence, these islands were classified as a National Geological Monument in 2001 by the Geological Survey of India.^[8][10]

The Deccan Traps that formed during Cretaceous–Eocene time about 60 million years ago emerged from the vast deluge of hot molten basaltic lava in the western part of India which is now seen as flat topped hills and step like terraces.^[1] Scientific studies carried out at the Indian Institute of Technology, Bombay on the petrology, palaeomagnetism and volcanics of the rocks of the island has brought out the following facts.^[11]

• Islands comprise fully of igneous rocks. They have acid composition that consist of dacites, rhyodacites, rhyolites and granophyres and carry basic patches.
• The columnar jointing pattern is well developed on Coconut Island.
• Mineralogically, plagioclase, K-feldspar, quartz, ortho- and clinopyroxenes, olivine, magnetite, and ilmenite are recorded in the ground mass phases
• Magnetic granulometric studies (susceptibility and hysteresis at different temperatures) of island rock samples indicate the presence of a multi domain (MD) state of magnetite. It is inferred that: "the formation of MD could have affected the stability and consistency of magnetic directions in these rocks" and that "this igneous body has been either annealed or could be an intrusive."

An analysis of palaeomagnetic data from India and Madagascar hypothesizes a new India–Madagascar fit related to the Late Cretaceous, directly prior to and during the early phase of Madagascar–India separation. A scientific study paper on Late Cretaceous India–Madagascar fit and timing of break–up related magmatism by several scholars reported in the Wiley Inter Science Journal states:^[12] "St. Mary magmatism is linked to the initial break–up between India and Madagascar, and magmatism probably resulted from rift related extensional processes initially induced by the Marion hotspot underlying southern Madagascar during the Late Cretaceous."

There are different theories on the age of the St. Mary's Islands rocks. In the analysis reported in the above section it has been further concluded that the multi domain (MD) state found in these rocks are uncommon in the Deccan Traps and non-existent in the Rajmahal Traps. Six selected samples from the islands were subject to whole rock K-Ar dating. This yielded a mean age of 93.1±2.4 (2σ) vis-à-vis the age of the Rajmahal Traps of about 105-100 Ma and about 66-35 Ma of the Deccan Traps. With this appreciation, the author has concluded that the igneous activity of St. Mary's Islands may represent Cretaceous-Tertiary igneous activity.^[11]

In a further analysis of the age of the break-up of Greater India (India plus Seychelles) and Madagascar it has been inferred to have occurred in the Upper Cretaceous at 88 Ma. The strength of this inference is based on the approach that the Felsic volcanics (rhyolites and Rhyodacites) of the St. Mary's Islands (SMI), Southern India, were originally interpreted as a distant outlier of the 66 Ma Deccan volcanic province of west–central India, comprising dominantly flood basalts. Later studies had dated it at 93 Ma by the K-Ar dating technique. Since the technique used was a simple use of an average of five out of six widely varying dates and arbitrary data selectivity chosen, the results were not considered reliable. A method of ⁴⁰Ar–³⁹Ar (argon–argon dating) of the SMI volcanic yields is reportedly more reliable of the plateau and isochron ages. The weighted mean isochron age is reported to be 85.6±0.9 Ma (2σ). The K–Ar (potassium-argon dating) technique adopted for the southern Indian Precambrian terrain, intruded by numerous mafic–doleritic dyke swarms, the age from Proterozoic to the latest Cretaceous is reported as 69–66 Ma (Deccan-related). The two regional dykes (a leucograbbro and a felsite) from the Kerala region of southwestern India, which were also dated earlier, indicate the age as 85 Ma. Madagascar flood basalt province's ⁴⁰Ar–³⁹Ar ages of 89–85 Ma tallies with the SMI volcanic age. The conclusion drawn by the study is that the Madagascar flood basalt province, the SMI volcanics, and possibly the Kerala dykes may well represent volcanic activity associated with the break-up of Greater India and Madagascar, in the Upper Cretaceous at 88 Ma.^[13]

Another scientific study on the biogeographic and tectonic history of India reported that:^[14] "Although real breaks among the lands were indicated by the physical data, faunal links were maintained by agile animals that were able to surmount minor marine barriers. India, during its northward journey, remained close to Africa and Madagascar even as it began to contact Eurasia."

A detailed description of the natural flora and fauna of the islands and the Deria Bahdur Ghur (the islands north of the port of Malpe, named after the cross set up by Vasco da Gama), have been compiled in a manual by John Sturrocks, the district collector of Mangalore in 1894.^[15]

The largely barren St. Mary's islands, due to coconut palm-fringed coast, is also called the "Coconut Island" (locally known as Thonsepar). The sparse inland vegetation is restricted to hardy shrubbery capable of growing in shallow, rocky soil and sandy terrain.^[16][17]

Birdlife

The island's rocky shores is a breeding site or stopover for various birds. Colonies of gulls, Scolopacidae (sandpipers) and a few crows have been sighted on the Islands. On the approach to the Islands from the Malpe beach, brahminy kites (Haliastur indus), great white egrets, grey egrets (breeding plumage) and groups of large Asian green bee-eaters have been recorded.^[18][16]

Coral

There is presence of corals in the surrounding waters.^[16]

Marine wildlife

The western coasts of the St. Mary's islands are abundant beachcombing and seashell haven with seashells of various shapes and sizes littered along the coast.^[19] The columnar basaltic rock formations provide a unique, rocky habitat that supports seaweeds and small crustaceans. Its marine life is dominated by 52 taxa of macroalgae (seaweeds), including 16 Chlorophyceae (green algae), 19 Phaeophyceae (brown algae), and Rhodophyceae (red algae).^[16]

St. Mary's Island are popular among tourist for their unique geology unique volcanic hexagonal columnar basalt rock formations, and small coral patches and rocky outcrops that support marine life such as clownfish and butterflyfish, making them suitable for snorkeling and scuba diving tours which can be booked from Malpe beach jetty.^[20] St. Mary's Islands is scattered with unique basaltic rock formations, specially in the north, southwest and south. The beach has security guards who ensure that visitors do not venture into danger zones of the islands.^[19]

Though the islands are bereft of resident population, buildings, hotels, resorts, or no domestic animals, there are tourist facilities such as covered pavilions with park benches on the shore and further inland, day time souvinir and food shop, toilets, etc. Visitors must carry drinking water and sunscreen since the climate is usually hot. Since the last few yards of the approach to the island involves wading, it may be preferable to avoid wearing sneakers. Visitors can wander around freely and enjoy the natural hexagonal-shaped rock formations from vantage locations.^[18]

Boats to St. Mary's Islands

All transport links to the island are only through the mainland town of Malpe, which is a major fishing harbor 5 km west of Udupi town, the administrative headquarters for the Islands.^[21] The only way of travelling to the St. Mary's islands is wo minutes ride by ferries and boats which depart regularly from Malpe Beach and the Tegma jetty, operating daily between roughly 9 am and 5:30 pm with an average frequency of 20 minutes, though they do not operate during the June-September monsoon season.^[1]

Malpe too has tourist attractions such as the 13th century Vadabhandeshwara Temple and an image of Balarama consecrated by the saint Madhvacharya, the founder of the Dvaita school of thought.^[21]

Airport

Mangalore International Airport at Mangalore, is 58 km (36.0 mi) south of Malape. The famous religious town Udupi, is about 60 km (37.3 mi) west-northwest of Mangalore.

Railway

Udupi railway station (Station Code: UD) on the Konkan Railway (map pictured), 4 km (2.5 mi) from Malape, connects to Indian Railways network including Kundapura, Goa, Ratnagiri, Mumbai, Kochi, Kazhakoottam, Kanjiramattom, and Thrippunithura.^[1]

Roads

Malape, is connected 5 km road to Udupi city from where motorists can access the NH66 which runs the entire length of Coastal Karnataka (called "Kanara"), NH169A to eastern and central Karnataka via Shimoga (Shivamogga), and Karnataka State Highway 37 to Sestern Gahats in southwest.

• National Geological Monuments of India
• List of places with columnar jointed volcanics
• Azores in the Atlantic Ocean
• Devils Postpile National Monument or The Cove Palisades State Park in the United States
• Fingal's Cave in Scotland
• Giant's Causeway in Northern Ireland
• Adam's Bridge in India-Sri Lanka border

Wikimedia Commons has media related to St. Mary's Islands.

• Udupi: St Mary's Islands – Nature at its Resplendent Best