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CSIR-NIO’s Research Provides Evidence for Burial of Parts of Harappan Port Town of Dholavira by Marine Sediments Possibly Transported by a Tsunami
Dholavira in Gujarat is a site of an ancient metropolitan town of the Harappan period. Dholavira was the largest port-town of the Harappans, and is the second largest Harappan site located within the present borders of India. This well-planned urban settlement flourished for about 1500 years from about 5000 to 3450 years before present. Archaeological excavations show that the township comprised of three parts - the castle, the middle town, and the lower town. A unique feature of Dholavira is the presence of a 14-18 meters thick wall, apparently built as a protective measure. Intriguingly, walls of such thickness are not found even in historic times when the conflicts have been more common and the weapons have become increasingly more destructive. Therefore, the real purpose of the Dholavira wall has been a topic of considerable debate. Recently a group of scientists deputed by Dr. SWA Naqvi, Director, CSIR-National Institute of Oceanography (NIO), Goa, and led by Dr. Rajiv Nigam, has proposed that the thick wall was built to protect the town from extreme oceanic events such as storm surges and tsunamis.
CSIR-NIO has carried out additional work at this site. A team of palaeoclimatologists, archaeologists and geophysicists from the institute surveyed a hitherto unexcavated area using Ground Penetrating Radar (GPS) and systematically collected soil samples. The GPR records show 2.5–3.5 meters thick homogenous soil layer (without any layering) below the surface; which suggests its episodic deposition, possible due to an extreme event. With the permission of the Archaeological Survey of India (ASI) a 2.5 m x 2.5 m trench was dug in the north-western corner of the Middle Town to a depth of 3.65 m. Fresh vertical section of homogenous soil thus exposed was sampled at regular intervals to infer the depositional history. The soil samples have been found to contain fossils of ‘foraminifera’, microscopic organisms that build calcareous shells and live only in seawater. This presence of shells of marine organisms in the soil strongly suggests an episodic deposition of marine sediments in the area. This deposition could have occurred as a result of a massive tsunami.
Tsunamis are known to have hit the region during the historical period. For example, the Makran Earthquake of 28th November 1945 generated a huge tsunami, over 10 meters in height, that devastated large areas along the northern shores of the Arabian Sea. The exact timing of the sediments deposited in Dholavira is yet to be established. However, the results clearly indicate that massive tsunamis are not uncommon in the region. The thick wall in Dholavira shows that the Harappans were not only aware of the potential threats from tsunamis, but they were also pioneers in coastal disaster management. Most importantly, results of this study opens he possibility that Dholavira, at least in part, could have been destroyed by such a tsunami.
The CSIR-NIO team comprised of Dr. VJ Loveson, Dr. AS Gaur, Shri Sundaresh, Shri SN Bandodkar, Shri Ryan Luis, Shri Gurudas Tirodkar and Miss Rupal Dubey.
400_0_some photos of Dholavira with plates.pdf
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