Using two or three sentences, describe the role of waves in shaping Earth's coastlines.

Waves are the busiest sculptors on the coastline. Built up by winds far out at sea, they unleash their energy and go to work when they break on the shore. Along much of the coastline, pounding waves slowly chip away the base of cliffs, forcing chunks of rock to crumble and slide into the sea.

(Paraphrase)

the role of waves in shaping Earth's coastlines is that Waves are the busiest sculptors of coastlines, unleashing their erosive power on the shore. Pounding waves slowly chip away the bases of cliffs, forcing chunks of rock to crumble and slide into the sea. Also, Smashing waves wear the softer rock, leaving harder rock behind in the form of sea stacks.