How flooding and earthquakes brought America's earliest civilisation to its knees

Natural disasters doomed America’s earliest civilisation 3,600 years ago when earthquakes and floods, followed by blowing sand drove away residents from an area that is now Peru.

University of Florida researchers studying the Supe Valley along the Peruvian coast say the successful farming community established 5,800 years ago was virtually swept away.

Anthropologist Mike Moseley said: ‘They had no incentive to change, and then all of a sudden, boom, they just got the props knocked out from under them.’

Excavated pyramids at the inland Supe settlement of Caral

Excavated pyramids at the inland Supe settlement of Caral

Until the disaster, the Supe thrived on land close to bays and estuaries, the researchers reported in the Proceedings of the National Academy of Sciences.

They fished with nets, irrigated fruit orchards and grew cotton and a variety of vegetables, says research co-author Ruth Shady, a Peruvian archaeologist.

They also built stone pyramids thousands of years before the better known Mayans.
'They’re impressive, enormous monuments,' Moseley said.

The largest so far excavated, the Pirámide Mayor at inland settlement Caral, measured more than 550 feet long, nearly 500 feet wide and rose in a series of steps nearly 100 feet high. Walled courts, rooms and corridors covered the flat summit.

But the Supe disappeared about 3,600 years ago and, after studying the region, the researchers believe they know what happened.

They found that a massive earthquake, or series of quakes, struck the seismically active region, collapsing walls and floors and launching landslides from barren mountain ranges surrounding the valley.

In addition, layers of silt indicate massive flooding followed.

Then came El Nino, a periodic change in the winds and currents in the Pacific Ocean, which brought heavy rains that damaged irrigation systems and washed debris into the streams and down to the ocean.

Sand and silt settled into a large ridge, sealing off the previously rich coastal bays.

In the end, land where the Supe had lived for centuries became uninhabitable and their society collapsed, the researchers concluded.

The study was funded by the University of Florida and the Heyerdahl Exploration Fund, University of Maine.

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