india

Updated: Jan 04, 2020 06:20 IST

New Delhi: Indian researchers have linked the decay of an advanced Harappan settlement to the disappearance of a river fed by Himalayan snow that once flowed in the Rann of Kutch.

The team from the Indian Institute of Technology, Kaharagpur, has said that climate change, a mega drought, and drying up a river that resembled the mythological Himalayan river Saraswati were behind the downfall of Dholavira, the most excavated of all Harappan settlements in India, nearly 4,300 years ago.

The study was published this week in the Journal of Quaternary Science.

The researchers from IIT-Kharagpur, Deccan College Post Graduate and Research Institute, Pune, Physical Research Laboratory, Ahmedabad, and Archaeological Survey of India, analysed the oxygen isotopes of the shell of a snail commonly consumed by the people in Dholavira to determine the water sources that sustained them.

“We found the snail shells finely cut by humans, suggesting that they were commonly consumed by the people there. These snails live in mangroves, which grew in the Great Rann of Kutch back then. The oxygen isotopes of the snail shell showed us that there was a seasonal mixing of river water in summer or monsoons with sea water that periodically inundated the Great Rann of Kutch,” said Anindya Sarkar, professor, department of geology and geophysics at IIT Kharagpur.

“These snails grew in a kind of water that is only possible if glacial meltwater mixes in the mangrove. This clearly suggested that a glacier fed river was debouching in the Rann of Kutch,” added Torsa Sengupta, the lead author of the paper and a PhD student.

“This is the first direct evidence of glacial fed rivers quite like the supposedly mythological Saraswati, in the vicinity of Rann,” Sarkar said.

This study shows that the settlements in Dholavira began nearly 5,500 years ago, in the pre-Harappan period and continued till about 3,800 years ago. The isotopes in the snail shells show that, between 4,300 to 4,100 years from ago, the glacial melt-water disappeared and the seasonality reduced.

The researchers said it was not certain why the river dried up, but the most likely explanation was the lack of precipitation. The changes in lifestyle of the people in Dholavira also reflected this change in climactic conditions, they added.

The Saraswati was mentioned in the Rig Veda, one of the four sacred canonised texts of Hinduism. The debate over its existence has been a serious issue of research for Indian historians, particularly over the last two decades.

“We saw that these settlements moved from a village economy to a town to an urban centre with great architecture and fortification. But from the later part of the mature Harappan period, we see a decline...showing a scarcity of resources,” said Dr RS Bisht, a co-author of the paper and former joint director general at Archaeological Survey of India.

“The drought was due to the disruption of the westerlies and Indian and East Asian monsoons at 4200 years back leading to ~250 year widespread drought. The collapse of Dholavira is very important evidence for reconstructing these global archaeological and climate events” said Prof Mike Walker of University of Wales, who in 2018 discovered the Meghalayan Age - the uppermost stage of the Quaternary period (about 2.58 million years ago till now).