02/1/14

Debunking the Adam Bridge


 

 

Adam's bridgeA story popped up on the internet in late 2013, recycled in early 2014, claiming “NASA Images Find 1.7 Million Year Old Man-Made Bridge.” Claptrap. It’s not a bridge. It’s simply a natural tombolo: “a deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar.”

The conspiracy theorists and some religious fundamentalists disagree.

It’s been called the Adam bridge, the Rama, Sethu (also Rama Setu – setu is Sanskrit for bridge), Ramar and the  Hanuman bridge, and Setubandhanam.

According to the legends in the Ramayana, the great Hindu epic poem, it was

…built by the Vanara (ape men) army of Lord Rama in Hindu theology with instructions from Nala, which he used to reach Lanka and rescue his wife Sita from the Rakshasa king, Ravana.

It’s a twisting stretch of shoal  and sandbank in the Palk Strait between India and Sri Lanka, about 18 miles (30km) long (depending on where you measure from, it can be reported as long as 35km). At high tide, the water is about 12 feet (4m) deep on average (apparently it ranges from 1m up to 10m deep in some places). The chain of shoals is roughly 300 feet (100m) wide.

It was reportedly passable on foot up to the 15th century until storms deepened the channel: temple records seem to say that Rama’s Bridge was completely above sea level until it broke in a cyclone in 1480 CE.

Let’s clear the first fallacy right away: the discovery of the “bridge” isn’t new, nor did NASA recently “discover” it in a photograph. Wikipedia tells us:

The western world first encountered it in “historical works in the 9th century” by Ibn Khordadbeh in his Book of Roads and Kingdoms (c. AD 850), referring to it is Set Bandhai or “Bridge of the Sea”. Later, Alberuni described it. The earliest map that calls this area by the name Adam’s bridge was prepared by a British cartographer in 1804, probably referring to an Abrahamic myth, according to which Adam used the bridge to reach a mountain (identified with Adam’s Peak) in Sri Lanka, where he stood repentant on one foot for 1,000 years, leaving a large hollow mark resembling a footprint.

The tombolo was photographed by NASA’s Gemini missions back in 1966 (photo here). However, that was before the internet existed to let wild and unsubstantiated conspiracy theories go viral.

Another NASA mission in 2002 produced a second photograph of the region (photo here) which, of course, spun the online conspiracy theorists off on a wild goose chase trying to “prove” it was the remains of a human-made structure connecting Sri Lanka with India.

Well, it isn’t. Wikipedia tells us it’s long been known as a natural formation, but that geologists differ in their views as to how it formed:

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. The friable calcerous ridges are broken into large rectangular blocks, which perhaps gave rise to the belief that the causeway is an artificial construction… which essentially consists of a series of parallel ledges of sandstone and conglomerates that are hard at the surface and grows coarse and soft as it descends to sandy banks.
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, 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.
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 Adam’s 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 geological process that gave rise to this structure has been attributed in one study to crustal downwarping, block faulting, and mantle plume activity 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…
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… 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’.

Continue reading