Researchers have discovered fresh evidence proving that a long spell of drought wiped out the Indus Valley civilization.
A paper published in the journal Geology recently by Yama Dixit, a PhD student at University of Cambridge, and her colleagues, claims fresh evidence for what was believed to be a long spell of drought around the time of the decline of the Indus Valley civilization. The data suggests that the monsoons stopped for about 200 years.
The civilization was destroyed about 4,000 years ago by a massive dry spell that coincided with the stopping of the monsoon cycle, say experts. The research team conducted studies on sediments in Kotla Dahar, a lake near the Indus Valley site in present-day Rajasthan. The lake is landlocked and gets flooded seasonally.
The shells of a particular kind of snail that existed in the lake during the Indus Valley civilization remain in the sediments. Carbon-dating studies on the lake by Yama and her team found that they contain calcium carbonate in a form called aragonite and the oxygen in it showed a rise in the level of Oxygen 18, a heavy isotope of oxygen that takes longer to evaporate. These sediments correspond to the dates of the drought.
S Settar, archaeologist and professor at the School of Humanities at NIAS, says, “This evidence can be accepted, probably, till fresh evidence comes along. The extensive Indus Valley civilization extending over thousands of kilometres came to an end all of a sudden. It could not have been a human act of invasion by an army that destroyed everything in a single stroke. It was some natural calamity that destroyed the planned cities and the lives of people. We can accept this evidence, but need more of it.”