Adam's Bridge

Ibn Khordadbeh's Book of Roads and Kingdoms (c. 850) refers to the structure as Set Bandhai (lit. Bridge of the Sea). The name Adam's Bridge appeared probably around the time of Al-Biruni (c. 1030).^[1] The name appears to have been based on the Islamic belief that Adam's Peak — where Adam, the first human, after his expulsion from the Garden of Eden, fell to the Earth — is located in Sri Lanka, and that Adam crossed over to peninsular India via the bridge.^[2]

The ancient Hindu epic Ramayana (8th century BCE–3rd century CE) mentions a bridge constructed by the Rama to reach the island of Lanka to rescue his wife Sita from Ravana. In popular Hindu belief, the bridge is identified as "Rama's Setu" (lit. Rama's bridge).^[1][3]

The Adam's Bridge is located between Pamban Island, off the southeastern coast of the Indian state of Tamil Nadu, and Mannar Island, off the northwestern coast of Sri Lanka. Along with the Pamban and Mannar islands, it separates the Palk Strait and the Palk Bay in the Bay of Bengal from the Gulf of Mannar in the Laccadive Sea.^[4]

The Adam's Bridge forms a discontinuous tombolo, made up of shoals of limestone, sand bars, and patch reefs, that stretches for 48 km (30 mi).^[5][6][7] There are uncertainties regarding the nature and origin of Adam's Bridge due to the lack of comprehensive field studies. The Marine and Water Resources Group of the Space Applications Centre of the Indian Space Research Organisation states that the formation comprises 103 small patch reefs. It is formed on a series of parallel ledges of sandstone and conglomerates that are hard at the surface and grow coarse and soft as they descend to sandy banks.^[7]

The Palk Strait is relatively shallow, with depths ranging from 1–35 m (3 ft 3 in – 114 ft 10 in).^[7] During the Last Glacial Period (115,000–11,700 years ago), the sea levels nearly 120 m (390 ft) lower than the present day levels. As the region was relativelt shallow, this exposed the seabed, which formed a land connection between the mainland Indian subcontinent and the island of Sri Lanka. Subsequently, the sea levels started to rise during the Holocene (11,700 years ago), and around 7,000 years ago, the Palk Strait and the bridge became completely submerged. Around 5,000 years ago, the bridge emerged again as the sea level fell in the region.^[8] A study tentatively concludes that there is insufficient evidence to indicate eustatic emergence and that the raised structure probably resulted from a local uplift.^[9]

• 
  Landsat 5 image of Adam's Bridge
• 
  NASA satellite photo of Adam's Bridge
• 
  Bathymetry map of Palk Strait

In the vicinity of Adam's Bridge, the water is typically only 1–3 m (3 ft 3 in – 9 ft 10 in) deep.^[8] Though the bridge itself was irregular, and discontinuous,^[10] due to the shallow waters, Adam's Bridge presents a hindrance to navigation through the Palk Strait. Though trade across the India–Sri Lanka divide has been active for several centuries, it was limited to small boats and dinghies. Larger ships from the west have had to navigate around Sri Lanka to reach India's eastern coast.^[11]

In the early 18th century, British geographer James Rennell, who surveyed the region, suggested that a "navigable passage could be maintained by dredging the strait of Ramisseram".^[12] In 1823, Arthur Cotton was assigned to survey the Pamban channel, which separates the Indian mainland from the island of Rameswaram and forms the first link of Adam's Bridge.^[13] A more detailed marine survey of Adam's Bridge was undertaken in 1837 by a team of Indian Navy engineers led by Francis T. Powell, along with draughtsman Felix Jones, and operations to dredge the channel were recommenced the next year.^[14]

Over the next century, several proposals were made for dredging the sea in the region. These included proposals by Alfred Taylor in 1860, Charles Townshend in 1861, British Parliamentary Committee in 1862, William Denison in 1863, George Robertson in 1872, John Coode in 1884, South Indian Railway in 1903, and Robert Bristow in 1922.^[15] However, these and subsequent efforts in the 19th century did not succeed in keeping the passage navigable for any vessels except those with a light draft.^[16]

Sethusamudram Shipping Canal Project

Further information: Sethusamudram Shipping Canal Project

After Indian independence, the Government of India had constituted five committees, in 1956, 1967, 1981, 1996, and 1997, to suggest alignments for a Sethusamudram canal project, aimed at creating a shipping route in the Palk Strait. These committees suggested various alignments, but none of them recommended cutting through the Adam's Bridge.^[15] The Sethusamudram Project Committee in 1956 strongly recommended against cutting across the Adam's Bridge.^[17]

In 1998, the Government of India approved the Sethusamudram Shipping Canal Project,^[18] and the project was sanctioned at a cost of ₹24.27 billion (equivalent to ₹82 billion or US$860 million in 2023), along a new alignment that required dredging through Adam's Bridge in 2005.^[19] However, several political parties and religious organisations opposed dredging through the bridge on religious grounds, and suggested to the government to take up an alternate alignment for the channel that avoids damage to Adam's Bridge.^[19][20] It was also opposed by environmental activists due to its location in the Gulf of Mannar Biosphere Reserve and concerns over its impact on the area's ecology, and local fishermen, who feared loss of livelihood due to adverse effects on fishing stock.^[18][21] Other concerns were raised including the potential loss of thorium deposits in the area and increased risk of damage due to tsunamis.^[22] Some organisations oppose this project on economic and environmental grounds and claim that proper scientific studies were not conducted before undertaking this project.^[23]

But, the then state and central governments opposed any changes to the proposed alignment, while maintaining that the current proposal was based on economic viability and environmental sustainability and that there were no other alternatives.^[24][25] The project was halted by the Supreme Court of India in 2009, with the government already having spent ₹8.293 billion (equivalent to ₹16 billion or US$160 million in 2023) on the project.^[18] While the government informed the Supreme Court in 2018 that it was considering alternate alignments, no work has happened since then.^[18][19]

As per Ramayana, the vanara army of Rama constructed a bridge to reach the island of Lanka to enable Rama to rescue his wife Sita from Ravana, the King of Lanka.^[1] In popular Hindu belief, Lanka is equated to present-day Sri Lanka, with the bridge identified with Adam's Bridge.^[3]

However, there are disagreements amongst scholars so as to the identity of the Lanka mentioned in the epic. While, the Ramayana does not explicitly state the geographic location of Lanka,^[28] few identify Lanka as located in the eastern part of present-day Madhya Pradesh,^[8][29] and few later literature in Sanskrit emphasise on the distinction between the Lanka in the epic and the present-day Sri Lanka.^[3] Author Robert P. Goldman, who edited the English translation of the Ramayana, opinied that it is a "fairy tale", and any attempts to probe into its historicity were misguided,^[28][d] with religious scholar John Brockington voicing a similar opinion.^[30]

In extant historical sources, the Kasakudi copper plates of Nandivarman II (c. late-8th century) pertaining to the conquest of Sri Lanka by one of his ancestors, equate Lanka with Sri Lanka, used as a justification of the imperial ambitions of the Cholas to invade the island. The link would then be co-opted by the Aryacakravarti dynasty of Jaffna in presenting themselves as the guardians of the bridge.^[3] However, medieval commentaries on the Ramayana such as the Ramanujiya (c. 1500 by Ramanuja) and Tattvadipika (c. 1550 by Mahesvaratirtha) , make a distinction between Lanka and Sri Lanka.^[31]

Islamic traditions hold that Adam's Bridge was crossed by Adam following his expulsion from the Garden of Eden.^[2]

In July 2007, S. Badrinarayanan, former director of the Geological Survey of India, has claimed that the structure is man-made.^[32] The Madras High Court directed the Indian Council of Historical Research to look into the evidence to ascertain whether it was man-made.^[33] NASA said that its satellite photos depict a natural feature and had been misinterpreted to make non-existent claims.^[34] A report from the Archaeological Survey of India found no evidence for the structure being anything but a natural formation,^[35] and informed the Supreme Court that there was no historical proof of the bridge being built by Rama.^[36][37]

In 2010, the Sri Lankan Tourism Development Authority promoted religious tourism from Hindu pilgrims in India by including the phenomenon as one of the points on its "Ramayana Trail", which drew criticism from some Sri Lankan historians as a distortion of history.^[38] The idea of Rama Setu as a sacred symbol to be appropriated for political purposes strengthened in the aftermath of protests against the Sethusamudram Shipping Canal Project.^[39]

In 2017, the Indian Council of Historical Research announced a pilot study into the origins of the structure,^[40] but later shelved it.^[41] In an episode of the Science Channel series What on Earth?,^[42] it is stated that those claiming that Adam's Bridge was constructed based their arguments on vague speculation, false implications, and the point that – as with many geological formations – not every detail of its formation has been incontrovertibly settled.^[43] Indian Geologist C. P. Rajendran described the ensuing media controversy as an "abhorrent" example of the "post-truth era, where debates are largely focused on appeals to emotions rather than factual realities".^[44][45]

• Adam's Bridge Marine National Park – National Park in Sri Lanka
• Bimini Road – Underwater rock formation near North Bimini island in the Bahamas
• Coral reefs in India
• Pamban Bridge – Railway bridge connecting Pamban Island to mainland India