If some resistant material slows or stops the downstream movement of a meander , a stream may erode through the neck between two legs of a meander to become temporarily straighter , leaving behind an arc-shaped body of water termed an `` oxbow lake '' or `` bayou '' .
However , if some resistant material slows or stops the downstream movement of a meander , a stream may erode through the neck between two legs of a meander to become temporarily straighter , leaving behind an arc-shaped body of water termed an oxbow lake or bayou .