Assalaam alaikum,
Very interesting topic, it seems there does exist a connection ( I say connection because it has not been proved to be mad made yet )between Sri Lanka and India.
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The article in nationmaster encyclopedia gives more detail on the formation of the bridge.
NationMaster - Encyclopedia: Ram sethu
Geology and ecology
Adam's Bridge consists of a series of parallel ledges of sandstone and conglomeration, that is hard at the surface and grows coarse and soft as it descends to sandy banks. In the 19th century, there were two prevalent theories explaining the structure. One considered it to be formed by a process of accretion and rising of the land, while the other surmised that it was formed by the breaking away of Sri Lanka from the Indian subcontinent. The friable calcerous ridges are broken into large rectangular blocks, which perhaps gave rise to the belief that the causeway is an artificial construction.
During periods of lowered sea level over the last 100,000 years, Adam's bridge has provided an intermittent land connection between India and Sri Lanka, which according to famous ornithologists Sidney Dillon Ripley and Bruce Beehler supports the vicariance model for speciation in some birds of the Indian sub-continent.
----The same article also states
Some archaeologists and geologists have presented differing estimates. Thus, a team from Centre for Remote Sensing (CRS) of Bharathidasan University, Tiruchi led by Professor S.M. Ramasamy in 2003 claimed that the, "Rama's bridge could only be 3,500 years old" and, "as the carbon dating of the beaches roughly matches the dates of Ramayana, its link to the epic needs to be explored".[23] Image File history File links NASA_satellite_photo_of_Rama's_Bridge.. . Image File history File links NASA_satellite_photo_of_Rama's_Bridge.. . Image File history File links No higher resolution available.. . Sethusamudram Shipping Canal Project proposes linking the Palk Bay and the Gulf of Mannar between India and Sri Lanka by creating a shipping canal through the shallow sea sometimes called Setu Samudram, and through the island chain of Ramas Bridge, also known as Adams Bridge.. . For the television series by Ramanand Sagar, see Ramayan (TV series).. . This article is about the American space agency.. .
Such claims were rejected as untenable by experts. NASA distanced itself from the claims saying that what had been captured was nothing more than a 30 km long, naturally-occurring chain of sandbanks called Adam's bridge. It also clarified that, "The images reproduced on the websites may well be ours, but their interpretation is certainly not ours. Remote sensing images or photographs from orbit cannot provide direct information about the origin or age of a chain of islands, and certainly cannot determine whether humans were involved in producing any of the patterns seen" Prof. N. Ramanujam, Head, Post Graduate Department of Geology and Research Centre, V.O. Chidambaram College, astrophysicist Jayant Narlikar and a group of professors of Madurai Kamaraj University stated that Adam's bridge is a natural geographical feature which formed some 17 million years ago.
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This article says
Asia Times Online :: South Asia news - Hindus say don't mess with Rama's Bridge
"Besides the ASI, historians, geologists, and earth and marine scientists have said the Ram Setu cannot be considered a man-made entity in the absence of material evidence."
Articles on the same topic, an interesting read.
Adam's Bridge - Rama Sethu.
Wa alaikum salaam