How is an Ox-Bow Lake formed?

In the lower course of the river, meanders (bends in the river) form when water is moving faster on one side of the channel than the other. Erosion takes place on the outsides of the bends, as the greater energy from the faster moving water causes horizontal erosion. On the other side of the channel, on the inside of the bends, deposition is occurring as the water is moving more slowly here.  The erosion causes the meander neck to narrow until eventually it breaks through. This often takes place when the river has more energy as in times of flood. The river now follows a straight path. After the meander has been cut through the river seals off the bend by deposition and an ox-bow lake is formed.