A river always takes the easiest course through channels and soft ground to the sea, flowing swiftly down mountain sides but much more slowly on the level plains.
On the plain the river takes advantage of every difference in gradient. This winding course is accentuated by the process of silting and erosion. As a river flows round a curve, the water on the outer bend moves more swiftly to cover the greater distance in the same time as the water flowing past the inner bend.
The more rapidly moving water will tend to wear away the banks of the channel, while the slower movement of the water on the inside wall will allow silting to take place. When the curve becomes more pronounced it is known as a “meander”. Notable examples of meanders are to be found in the Wye in England, and the Meuse in France.
Sometimes the river erodes the bank so fiercely that a new channel is formed, leaving as island of earth in the middle of the stream.