Waterfalls close waterfallA vertical cliff of water where the water flows over a layer of hard rock on top of a layer of softer rock. The softer rock is eroded away causing the cliff edge to ...

At 4,130 miles (6,650 km) long, the Nile in Africa is the longest river in the world. Some people consider the Amazon in South America to be longer. This is because the many hundreds of channels ...