What process occurs when materials in a river run against the banks and erode them?

The correct answer is corrosion, often referred to as abrasion in this context because it describes the process of the riverbed materials wearing away at the riverbanks through friction and impact. When sediments and rocks within the river flow collide with the banks, they act like sandpaper, gradually grinding down the materials that make up the riverbanks. This process contributes to the overall shaping and changing of the landscape over time, often resulting in wider and deeper river valleys.

Hydraulic action, on the other hand, involves the force of moving water itself eroding the banks, but it doesn’t specifically involve the materials within the water colliding with the banks. Attrition refers to the process where rocks and pebbles collide with each other in the flow of the river, becoming smaller and more rounded, rather than eroding the banks themselves. Solution pertains to the chemical process where soluble materials dissolve in water, which does not involve mechanical erosion of the banks. Thus, the selecting of abrasion as the answer accurately identifies the mechanical interaction that causes erosion along riverbanks.