The running water in the river erodes the landscape. When the river tumbles at a steep angle over very hard rocks or down a deep valley side it forms a waterfall. While entering the plain the river twists and turns and forms large bends which are known as meanders. Due to continuous erosion and deposition along the sides of the meander, the ends of the meander loop come closer and closer.
In due course of time the meander loop cuts off from the river and forms a cut-off lake, which is also called an ox-bow lake. Sometimes, the river overflows its banks causing flood in the neighboring areas. As it floods, it deposits layers of fine soil and other material called sediments along its banks. As a result—a fertile floodplain is formed. The raised banks are called levees.