What is a form of stream erosion that involves the wearing away of rocks and sediment?

Attrition is a specific form of stream erosion that occurs when rocks and sediment in the water collide with each other, leading to their gradual wearing away. This process is particularly relevant in dynamic environments like rivers and streams where the movement of water causes particles to bump against one another, effectively smoothing and reducing their size over time. The constant movement of water, combined with the abrasive action of these colliding particles, results in the physical breakdown of larger rocks into smaller pieces, maintaining the cycle of erosion.

The other terms presented do not accurately describe this process. Abstraction refers to the removal of something, such as water or minerals, rather than the mechanical wearing away of materials. Consolidation typically pertains to the process by which particles come together, increasing the stability of sediments, which contrasts with the idea of erosion. Accretion involves the gradual accumulation of sediment or rock material, often in a deposit form, which is opposite to the concept of wearing away. Thus, attrition is the most fitting choice in the context of stream erosion.