26 August 11
Brazil's National Observatory believes that it's found an enormous underground river flowing 4km below the Amazon rainforest.
By studying temperature variations at inactive oil wells drilled in the 70s and 80s by the state-owned Petrobras oil company, geoscientists obtained data showing the movement of water far below the course of the Amazon river on the surface. It's thought to be about 6,000km long, which would make it about the same length as the Amazon.
It's been named after Valiya Mannathal Hamza, who led the research team that made the discovery, and has been studying the region for more than four decades. The Hamza river flows west to east, like its surface counterpart, but it has a flow rate calculated to be around 3,000 cubic metres per second -- which is a mere three percent of the Amazon river itself.
That's still plenty, though -- more than 46 times the flow of the Thames in London -- and it represents a secondary drainage system for the Amazon basin.
It's thought to empty into the Atlantic Ocean deep below the surface, and a statement released by the research team claimed it could be responsible for the low levels of salinity found in the waters around the mouth of the Amazon.