lateral erosion

(geology) The action of a stream in undermining a bank on one side of its channel so that material falls into the stream and disintegrates; simultaneously, the stream shifts toward the bank that is being undercut.

Usually of rivers; erosion of the banks rather than the bed. In a stream or river, it results in undercutting of the banks; in deserts, lateral erosion by sheet flow may be responsible for the formation of desert scenery.