How does a river "pluck" particles?
A) hammer-like action of particles against the particles that are lodged in the side of river canyons
B) force of water rushing against particles in solid rock
C) scouring action of particles around the rock which encloses the rock that is plucked
D) shear stress of water against joints and cracks

Question

Quizplus · Accepted Answer

"Plucking" occurs when water flowing over bedrock creates pressure differentials across cavities and fractures in the rock. The water pressure can be intense enough to lift off pieces of rock along the fractures and carry them downstream. This phenomenon is most effective when water is flowing rapidly and when the rock is already weakened by freeze-thaw cycles or other weathering processes. This process is known as the shear stress of water against joints and cracks.

How Does a River "Pluck" Particles