Our World

Amazon Once Flowed in the Opposite Direction

When studying the amount of time it takes for sediment to travel down the Amazon, a team of geologists accidentally discovered that the river used to flow in the opposite direction. When I first heard that, I was very skeptical because I didn't think that it was possible. I suggest you read the article because it goes more in depth, but here is a summary of how this could happen. First, it starts with the Pangea theory, or when the continents of the world were connected. At this point in time, the Amazon (or what exsisted of it back then) flowed in the normal direction (West to East). When South America separated from Africa about 130million years ago, the east coast of South America was uplifted. We all know that water won't ususally flow uphill, so we can assume that this is when the entire river system began flowing West to East. So why isn't it like that today? Remember in class that we talked about the Andes being a relatively young range in geoglogical terms? They were formed about 65 million years ago, which is what cause the Amazon to eventually switch back to its original direction and the flow we are familiar with today.

The scientist were able to come up with this theory based on indicators of the ancient sediment, including ripple marks and mineral traces. Earlier studies have shown that segments of the Amazon Basin onced flowed the opposite way, but this is the first time evidence has been found that applies it to the entire basin. Because of this find, searches for oil might be moved to where the ancient Amazon fan was being deposited in hopes of finding those sorts of natural resources.

posted by Anonymous @ 10/26/2006 08:10:00 PM