The combined effects of mass wasting and running water produce stream valleys, which are the most common and conspicuous of Earth’s landforms. If streams alone were responsible for creating the valleys in which they flow, the valleys would be very narrow features. However, the fact that most steam valleys are much wider than they are deep is a strong indication of the significance of mass-wasting processes in supplying material to stream. The walls of a canyon extend far from the stream because of the transfer of weathered debris downslope to the stream and its tributaries by mass-wasting processes. In this manner, stream and mass wasting combine to modify and sculpt the surface. Of course, glaciers, groundwater, waves and wind are also important agents in shaping landforms and developing landscapes.