In three ways: by sheer force of impact, by electromagnetic disruption of molecular bonds and by dissolution of minerals. You can't see any of this happening in usual time, but if you visit an area of shoreline after many years, you'll see where it's happened.
the waves come to the shoreline, cliffs, etc. and when they get there, they take little bits of their material every time they pull back
Waves hit the rock and takes little bits of rock
A wave cut platform is formed. == ==
Waves keep hitting the side of a cliff and eventually erode enough rock to form a cave
Waves erode rock through abrasion, where particles carried by the water bump into and wear away the rock surface. Hydraulic action occurs when the force of breaking waves compresses air in cracks in the rock, causing it to weaken and eventually break off. Corrosion is another way in which waves erode rock, as the minerals in the rock dissolve in seawater over time.
As the waves roll in more and more, the rock or mineral weakens and soon erodes down. It makes the rock thinner and less dense.
things that erode weathered rock
A cave is sometimes created when waves erode a headland.
because waves roll against it. forcing it to erode
Waves erode a coast by their continuous and repeated actions of swarsh\uprush and retreats\backwash.
Wave-cut cliff
Wave-cut cliff
Mechanical action.
The two processes by which waves erode the land are impact and abrasion