Waves are indeed powerful and dynamic agents, continuously modifying coastal geomorphology through processes of erosion, transport, and deposition. Their energy, derived from wind, is relentlessly expended upon shorelines, shaping them into a diverse array of landforms.

Erosion: Waves actively erode coastlines primarily through hydraulic action, where the sheer force of water compresses air in rock crevices, causing them to shatter, and by abrasion, where rock fragments carried by waves grind against the coast. Attrition further breaks down these fragments. This erosional power carves out distinctive features. For example, sea cliffs are steep rock faces formed by sustained wave attack at their base, creating wave-cut notches. Over time, these notches expand, leading to the collapse of the overhanging cliff, which retreats landward. The eroded material forms a gently sloping wave-cut platform at the base of the cliff, exposed at low tide. In headlands, differential erosion can create sea caves, which may eventually extend through to form sea arches, and ultimately collapse to leave isolated sea stacks.
(Diagram Description: A cross-section showing a vertical cliff face with a notch at its base, leading to a flat, horizontal wave-cut platform extending seaward. Another diagram might illustrate a headland with a sea cave, progressing to an arch, and finally a detached stack in the water.)

Transport and Deposition: Waves are also highly effective at transporting sediment along the coast. Longshore drift, driven by waves approaching the shore at an angle, carries sand and gravel in a zigzag pattern along the beach face. This continuous movement results in the deposition of material in sheltered areas. Beaches themselves are prime examples of wave deposition, composed of sand and pebbles sorted and accumulated by wave action. Where the coastline changes direction or sediment supply is abundant, longshore drift can build spits, which are narrow strips of land projecting into a body of water. If a spit connects an island to the mainland, it forms a tombolo. Bars can form offshore, parallel to the coast, by the deposition of sediment by breaking waves.

Thus, the relentless energy of waves, whether carving out formidable cliffs or building serene beaches, undeniably orchestrates the ever-changing face of coastal geomorphology, creating a dynamic and fascinating landscape.