When a ﬂooding river straightens its channel by eroding a cut-off across the neck of a meander, it leaves behind an abandoned loop of former channel, a meander scar. If groundwater seepage or overﬂow from the river ﬁlls the scar with water, it becomes an oxbow lake. Eventually, however, sediment and vegetation accumulate in an oxbow to such an extent that only the depressed scar of the former channel remains. Meander scars develop at multiple scales, from small creeks to great rivers. They are typically wetter and biologically richer than surrounding lands, and seen from above, their crescent shapes impart a dimpled beauty to the land.