Waterfall

• Waterfalls for over bands of more and less resistant rock. Differential erosion takes place where the softer rock is more easily eroded than the harder rock.
• Hydraulic action takes place, when water flows over the hard rock and air is compressed into the riverbank causing materials to be dislodged.
• The dislodged materials fall and swirl around creating a deep plunge pool through the process of abrasion, when the force of the water throws bedload against the banks causing erosion.
• Undercutting causes an overhang of the hard rock and over time the hard rock becomes unsupported and collapses due to gravity into the plunge pool.
• Attrition can occur here, which erodes the waterfall further upstream towards the source forming a gorge
• An example of a waterfall is Niagra Falls