Vaupés Arch

basin of the Amazon from the headwaters of the Orinoco for the first time. Much of the Arch is now buried under thick sediments washed from the Andes. Shifting meanders of the area's numerous waterways have spread these sediments evenly over the flat alluvial plain, which has very little relief. In modern times the Casiquiare canal, to the south of the Arch, reconnects the two headwater basins, the Upper Orinoco and the Upper Rio Negro