-=Welcome to the apwiki Rivers page=- Streams and rivers are the waterways running downwards on the surface of the Earth. They are caused by falling ((rain)). Rivers start as streams generally form moutains or mountainous regions. Their source of water might be underground springs, marshes, melting ((glaciers)) or rivulets. The friction of the running water on its land bed and banks cause erosion of soil making silt and rolling stones break to make sands. It is the friction that gives the rivers the power to carve out landscape, tunnelling gorges, valleys, deltas and they also make waterfalls by falling from a height. As the streams flow downwards they form rivers, and the rivers join another rivers to make big rivers. The joining streams and rivers are called tributaries. The river finally join one or the other ((sea)).