The age of Ram Setu

Source: By Anjali Marar: The Indian Express

In possibly a first, Indian scientists will undertake a scientific expedition to date the chain of corals and sediments forming the Ram Setu. Also known as Adam’s bridge, this 48-km long bridge-like structure between India and Sri Lanka finds mention in the Ramayana but little about its formation is known or proven, scientifically.

Recently, a central advisory board on archaeology, functioning under the Archaeological Survey of India, approved the project proposal submitted by CSIR – National Institute of Oceanography (NIO), Goa to study the sediments and determine its origin.

CSIR-NIO will undertake a three-year scientific project. “The idea is to see whether Ram Setu is a man-made structure or not. The most important aspect of the project is to establish its age, scientifically. Once it is known, the information can be verified and co-related with its mention in the Ramayana and similar scriptures,” said Prof Sunil Kumar Singh, director, NIO.

Carbon dating techniques, which are now available in India, will be primarily used to determine the age of the sediments.

Broadly, the explorers will apply a number of scientific techniques while attempting to date the Ram Setu, study its material composition, and outline the sub-surface structure along with attempting to excavate remnants or artifacts, if any, from the site.

The project is expected to formally commence by the end of March. An initial survey will make use of underwater photographs to check if any habitation remains inundated in the area. A geophysical survey will be performed to understand the structure.

“Over the years, several kinds of depositions, including sand, have covered the actual structure. Initially, only physical observation, and no drilling, will be done. A scientific survey will be performed to understand the sub-surface structure,” said Singh.

Once this is fully understood, the scientists plan to drill into the structure, gather samples and later perform laboratory-based studies.

The NIO director added, “Some scriptures mention wooden slabs along the Setu. If so, they should have fossilised by now, which we will try to locate. Using high-end techniques, we will look for corals and date the gathered samples. NIO is equipped with the latest technology. Most of the scientific analysis will be done at NIO or within laboratories in India.”

The team will mainly comprise seasoned archaeologists, trained in diving, along with scientists to perform bathymetry – the study of ocean floors – and seismic surveys.

As the locality around Ram Setu is shallow, with depth not more than 3 to 4 meters beneath water, the scientists will use local boats to ferry along the Setu. This is because large vessels or ships cannot sail at such shallow depths.

NIO operates two oceanographic vesselsRV Sindhu Sankalp (ability to go up to and remain 56 metres underwater) and RV Sindhu Sadhana (ability to go up to and remain 80 metres underwater).

For collecting core samples at greater depths and for bathymetry purposes, Sindhu Sadhana will be deployed for the Ram Setu project.

Two of the planned tests:

Side scan SONAR — will provide bathymetry which is similar to studying topography of a structure on land. Soundwaves signals will be sent to the structure which will provide an outline of the physical structure of the Ram Setu.

Silo seismic surveyMild earthquake-like tremor shocks will be sent at shallow depths close to the structure. These energised shockwaves are capable of penetrating into the structure. The reflected or refracted signals will be captured by instruments that will provide sub-surface structure.

What makes underwater archaeological explorations significant?

India has a vast coastline of over 7,500 kilometres. Oceans are a treasure trove of the past recordsclimate, evolutionary changes of the underwater fauna, coastal lives, habitations, settlements and civilizations. Of these, the sea-level changes remain the most significant of all with respect to climate studies.

History has records of sailors who set out on unknown voyages to later discover new lands and islands. They ventured into deep seas even before the advent of the Global Positioning System (GPS). Using such underwater exploration studies, scientists say that it is possible to trace numerous shipwreckages and remains from the past. Studies of ship wreckage, artifacts or remains could reveal a lot of information.

Has India undertaken underwater archaeological explorations?

A part of Dwarka, along the coastal Gujarat, is underwater, confirming the sea-level rise. The NIO has been studying this site, and so far, traced large amounts of scattered stones which were retrieved at the depth between three to six metres beneath. Stone anchors, too, were found at the site, suggesting it to be part of an ancient harbour. In the past, NIO had initiated studies to trace the missing shore temples of Mahabalipuram in Tamil Nadu.

Presently, several ship wreckage studies, including the one off the Odisha coast, are going on. Scientists have identified and are considering a port located close to Goa for similar scientific study.