What caused the Amazon river to reverse direction? Scientists have long debated what caused this reversal, but a new study using computer modeling suggests that cause might have been a massive amount of slow, yet steady, erosion from the Andes mountains as they grew, millions of years ago.

Image: Amazon River / NASA

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DISCUSSION

steverman
Chip Skylark of Space

there's a river in Nova Scotia called the Avon and one in St. John's NB that reverses twice a day on the high tide. They're on the Bay of Fundy, and water is funneled up stream, forcing a tidal bore up the river. The mouth of the Amazon is also funnel shaped, with likely the same effect.