User:CHANDAN KUMAR PODDAR/sandbox

"Project Rameswaram", the Geological Survey of India (GSI) concluded through the dating of corals that Rameswaram Island evolved beginning 125,000 years ago. Radiocarbon dating of samples in this study suggests that the domain between Rameswaram and Talaimannar may have been exposed sometime between 7,000 and 18,000 years ago.[28] Thermoluminescence dating by GSI concludes that the sand dunes between Dhanushkodi and Adam's Bridge started forming about 500–600 years ago.[28] .RAM ....Hindu belief is that the bridge was created by Shri Rama and Shri Lakshman with the assistance of Lord Hanuman and the vanara army to reach Lanka in order to find Shri Rama's wife Sita who was kidnapped by Ravana. Pamban Island (Tamil Nadu, India) with its small port of Rameswaram is about 2 km from mainland India. The Pamban Bridge crossing the Pamban channel links Pamban Island with mainland India. It refers to both: a road bridge and a cantilever railway bridge. Small boats would go below the 2065 m long road bridge and the railway bridge would open up.

The problem in navigation exists because big ships cannot travel in the shallow waters of the Pamban channel. Dredging in this channel would cost more than dredging a channel in the Rama Setu area, where the waters are comparatively deep and lesser earth would have to be dredged. Hence, in 2005, the Government of India approved a multi-million dollar Sethusamudram Shipping Canal Project that aims to create a ship channel across the Palk Bay cutting across Rama Setu. Various organizations have opposed the project based on religious, economic and environmental grounds and have sought the implementation of one of the alternative alignments considered during the earlier stages of the discussion.

A ferry service linked Dhanushkodi in India with Talaimannar in Sri Lanka. The service was part of the Indo-Ceylon Railway service during the British Rule. One could buy a railway ticket from Chennai to Colombo, whereby people travelled by rail from Chennai to Pamban island, go by ferry to Talaimannar, and then go again by rail to Colombo. In 1964, a cyclone completely destroyed Dhanushkodi, as a train was about to enter the station. The tracks and the pier were heavily damaged along the shores of Palk Bay and Palk Strait.[25] Dhanushkodi was not rebuilt and the train then finished its journey at Rameswaram. There was a small ferry service from there to Talaimannar, but it was suspended around 1982 because of the fighting between Sri Lankan government forces and the separatist LTTE.

Geological evolution

Landsat 7 Image of ram sethu's Bridge

Landsat 5 image of Adam's Bridge Considerable diversity of opinion and confusion exists about the nature and origin of this structure. 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 mainland.[26] The friable calcerous ridges are broken into large rectangular blocks, which perhaps gave rise to the belief that the causeway is an artificial construction.[27]

According to V. Ram Mohan of the Centre of Natural Hazards and Disaster Studies of the University of Madras, "reconstruction of the geological evolution of the island chain is a challenging task and has to be carried out based on circumstantial evidence".[28] The lack of comprehensive field studies explains many of the uncertainties regarding the nature and origin of ram sethu Bridge, which essentially consists of 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.[citation needed]

Studies have variously described the structure as a chain of shoals, coral reefs, a ridge formed in the region owing to thinning of the earth's crust, a double tombolo,[29] a sand spit, or barrier islands. It has been reported that this bridge was formerly the world's largest tombolo before it was split into a chain of shoals by the rise in mean sea level a few thousand years ago.[30]

Based on satellite remote sensing data, but without actual field verification, the Marine and Water Resources Group of the Space Application Centre (SAC) of the Indian Space Research Organisation (ISRO) states that ram sethu Bridge comprises 103 small patch reefs lying in a linear pattern with reef crest (flattened, emergent – especially during low tides – or nearly emergent segment of a reef), sand cays (accumulations of loose coral sands and beach rock) and intermittent deep channels. The coral reefs are designated by the different studies variously as ribbon and atoll reefs.

The geological process that gave rise to this structure has been attributed in one study to crustal downwarping, block faulting, and mantle plume activity [31] while another theory attributes it to continuous sand deposition and the natural process of sedimentation leading to the formation of a chain of barrier islands related to rising sea levels.[28] Another theory affirms that the origin and linearity of ram sethu's Bridge may be due to the old shoreline – implying that the two landmasses of India and Sri Lanka were once connected – from which shoreline coral reefs evolved.

Another study explains the origin the structure due to longshore drifting currents which moved in an anticlockwise direction in the north and clockwise direction in the south of Rameswaram and Talaimannar. The sand was supposedly dumped in a linear pattern along the current shadow zone between Dhanushkodi and Talaimannar with later accumulation of corals over these linear sand bodies.[citation needed] In a diametrically opposing view, another group of geologists propose crustal thinning theory, block faulting and a ridge formed in the region owing to thinning and asserts that development of this ridge augmented the coral growth in the region and in turn coral cover acted as a `sand trapper'.[citation needed]