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Tuesday, October 20, 2015

Wedding of the Waters

When traveling with EarthView, we often point out an intriguing geographic oddity in the middle of the world's largest rain forest -- the "wedding of the waters" at Manaus, in the center of the Amazon Basin.  Two members of the EarthView team have actually visited this amazing feature.
It is part of our more general lesson about the importance of rivers and the fact that rivers are actually river systems. What we know by a single name -- such as the Charles, the Nile, the Mississippi, or the Hudson -- is actually a network of streams that flow toward each other and toward a common discharge into a larger river, sea, or ocean. These river networks are said to drain a river basin or drainage basin.

In the case of the Amazon Basin, an extraordinary river has some extraordinary characteristics. A dozen of its tributaries are each over 1,000 miles long -- the Xingu, the Madeira, and many others would be significant river systems on their own. And more than 1,000 tributaries have been named -- smaller systems such as the Rio Candeias (Candles River) in Rondonia. Many smaller tributaries have not been named.

But of all the tributaries of the Amazon, it is the confluence of two major streams near Manaus that is most extraordinary. The Rio Solimões looks like coffee full of cream, as it brings sediment from the steep slopes of the Andes; the Rio Negro resembles black tea with nothing in it, because of its tannic acids. It is similar to many of the streams we find in New England, particularly in forested areas in the late autumn. It flows very slowly from the Guyana Highlands, carrying ample sediments.

Expedition leader Allan Marshall from the Florida Aquarium gives students an entertaining way to learn some of the details of this incredible location, where the one of the world's great rivers is actually formed.

Fascinating, but not unique: As amazing as the Wedding of the Waters is, it turns out that many similar phenomena can be found around the world, where rivers with very different characteristics come together and for a variety of reasons do not immediately mix.

Dr. Hayes-Bohanan prepared the Confluences Map to highlight ten of these interesting locations, based on an article from the Twisted Sifter blog. The map allows you to follow each of the tributaries toward its source, to investigate what makes it distinctive.

Map snapshot. View all of the confluences on the Dynamic Map.

More learning: The Amazon Basin -- specifically the state of Rondonia in its western portion -- was Dr. Hayes-Bohanan's introduction to geography. Learn about his three journeys there (including one with his three-year-old daughter) and about everyday life in the Amazon from Folha da Fronteira on his Rondonia Web pages.

Even more learning: Look at a map to see what river is closest to your own house or school. Do any smaller rivers flow together upstream to form this river? Does it join with any others as it flows toward the sea? If you could put a canoe in the river, where could you take it?

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