Meanders are bends in a rivers course. Water flowing around a meander moves fastest on the outside of the bend leading to erosion and the formation of a steep river cliff. On the inside of the bend, water slows down leading to the deposition of sediment. This forms a gently-sloping slip off slope in the shallow water.

Lateral erosion by meanders leads the widening of the valley floor (floodplain). Meanders often migrate downstream and become wider and larger over time.

Where there are well developed meanders, a river may take a short-cut across a narrow meander neck in times of flood and this leads to the creation of sections of abandoned river called ox-bow lakes. Over time, the ox-bow lakes dry up and leave just a meander scar.