Oxbow Lakes/Cutoff Meanders
Oxbow lakes form as a natural part of the evolution of a meandering stream channel. Meandering channels deposit sediment along the inner part of each meander--creating point bars--and erode away sediment on the outer part of each meander--creating cut banks. This pattern is due to differences in flow rate around curves (faster on the outside, slower on the inside). Over time, this causes those curves to twist inward, until the beginning and end of the meander overlap, connecting the channel in a straighter line, and cutting off the over-curved meander. This cutoff meander remains--often still full of water--as an oxbow lake.