Recent glacier retreat across the Andes is unprecedented in the history of human civilization.
Scientists carbon-dated bedrock that had been recently exposed by the retreated glaciers by measuring beryllium-10 and carbon-14 nuclide levels and found that concentrations were nearly zero.
These glaciers are smaller than they've been since the last interglacial period, which ended about 115,000 years ago.
The rock hadn't been exposed during the Holocene Era, which dates back 11,700 years.