Why the Amazon River Reversed Its Flow
It's linked to erosion and the Andes, researcher finds
By Matt Cantor, Newser User
Posted Jul 20, 2014 7:28 AM CDT
This 2013 photo shows Amazon jungle guide Shane Zammette surveying the shorelines on the Amazon River about 100 miles from Manaus, Brazil.   (AP Photo/Jeremy Hainsworth)

(Newser) – The Amazon River flows eastward toward the Atlantic, but researchers know that wasn't always the case, notes the Latin Times. Long ago, the region's water moved in the opposite direction. Just what was it, though, that caused the reversal? Earlier findings linked the shift to the movement of molten rock deep underground, but a new study contests that. A geophysicist at Brazil's University of Sao Paolo used expansive computer modeling to come to a different conclusion: It's all about erosion related to the rising Andes Mountains as they grew millions of years ago, Science reports.

Victor Sacek's model, laid out in Earth and Planetary Science Letters, shows how the region's terrain might have developed over 40 million years, and its results match real-life geological findings. Here's what it suggests: The downward push of the Andes Mountains created a trough that resulted in lakes. Afterward, sediment poured into these lakes and created higher terrain. That led, 10 million years ago, to ground that sloped from the mountains to the Atlantic—and drove the water in that direction. (Meanwhile, scientists think they've figured out where the river actually starts.)

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Showing 3 of 8 comments
Flechette
Jul 21, 2014 12:02 PM CDT
Global warming, and it was also Bush's fault. Bush causes the river to reverse when he extincted the dinosaurs...
Ezekiel 25:17
Jul 20, 2014 4:40 PM CDT
It is totally fascinating looking at the characteristics of South America. You just do not realize most of it is east of Florida. Brazil is so close to Africa and explains the presence of slaves. Its like driving between Dallas and Philly. Is also interesting in how the super-continent separated to create the Atlantic ocean. In reversing rivers, man did it to the Chicago river so that blood, guts, entrails, and sewage wouldn't run from the pork plants into Lake Michigan. It was not easy to do. They had to raise all of the buildings and factories up several feet so they could build up the river on the high side and force it to flow west into the upper Mississippi.
hhicp1
Jul 20, 2014 10:45 AM CDT
its just a matter of time so ignorant fool blames it on man made global warming