Amazon River Dated at 11 Million Years Old

A new drilling study has definitively dated the Amazon River at over 11 million years old, and it has held its current form for at least the last 2.4 million years.

The Amazon is one of the two longest rivers in the world, and its flood basin is home to one third of all the species on Earth. Discovering the river’s age is a stark reminder of just how ancient and intertwined the Amazonian ecosystem is, including the immensely rich biodiversity which calls it home.

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The age was derived from samples taken from two boreholes drilled near the mouth of the river, one of which was 2.6 miles below sea level. Before now, the age of the Amazon was completely unknown, mostly because scientific drilling expeditions could only reach a small fraction of more ancient sediment layers.

The discovery should bring much needed insight into the history of the river, and it has great implications for better understanding South American paleogeography as well as the evolution of the unique aquatic organisms of the Amazon.

Interestingly, despite its impressive 11 million year old age, the Amazon is actually considered a relatively young river compared to some of the Earth’s oldest. The Nile in Africa and the New River in North America are thought to be hundreds of millions of years old.

Perhaps more incredible than being one of the two longest rivers in the world is the Amazon’s water volume. The river has a total river flow greater than the next eight largest rivers combined, and the drainage basin accounts for approximately one fifth of the world’s total river flow. That adds up to 20% of all the fresh water that is entering the oceans from rivers on Earth. In fact, out from the mouth of the Amazon, potable water can be attained in the Atlantic Ocean even after the coastline is no longer visible.

The basin is vital, not only because of its volume of fresh water and biodiversity, but because of its role in the Earth’s climate. While the river has held intact in its current form for 2.4 million years, that form is threatened by modern development. Dams, roads, slash and burn agriculture and other forms of encroachment could radically alter this ancient ecosystem, and that would have unforeseen and profound effects around the globe.

If this discovery sheds light on just one thing, it’s on how frighteningly quick modern development can change a massive natural system– even one as seemingly unlimited as the Amazon– relative to the speed by which nature operates.

Source: LiveScience

Image Credit: markg6 on Flickr under a Creative Commons License

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