Formation of a river. Computer illustration showing how the shape and path of a river alters and develops as it erodes its way through its environment. The water flowing around the outside of the bend flows faster than the water going around the inside. The faster water tends to erode the river bank more quickly whilst the slower water will deposit sediment that it is carrying. The meanders (bends) increase in size until there are only narrow necks of land between them. Eventually the river cuts through the neck leaving an oxbow lake.