New research involving Cambridge University has found evidence — locked into an ancient stalagmite from a cave in the Himalayas — of a series of severe and lengthy droughts which may have upturned the Bronze Age Indus Civilization.
The beginning of this arid period — starting at around 4,200 years ago and lasting for over two centuries — coincides with the reorganization of the metropolis-building Indus Civilization, which spanned present-day Pakistan and India.
The research identified three protracted droughts — each lasting between 25 and 90 years — during this arid period. “We find clear evidence that this interval was not a short-term crisis but a progressive transformation of the environmental conditions in which Indus people lived,” said study co-author Prof Cameron Petrie, from Cambridge’s Department of Archaeology.
The researchers charted historic rainfall by examining growth layers in a stalagmite collected from a cave near Pithoragarh, India. By measuring a range of environmental tracers — including oxygen, carbon and calcium isotopes — they obtained a reconstruction showing relative rainfall at seasonal resolution. They also used high-precision Uranium-series dating to get a handle on the age and duration of the droughts.
Read more at University Of Cambridge
Image: A section through the Dharamjali stalagmite that the authors studied. Credit: Alena Giesche