As waves approach the shore, they enter shallower water. This causes the waves to slow down, as the friction of the water against the bottom of the ocean slows them down. As the waves slow down, they also get taller. This is because the water in front of the wave is no longer moving forward as quickly, so the water piles up behind the wave, making it taller.

Rock structures:

Rock structures can affect waves by reflecting, refracting, and diffracting them.

* Reflection occurs when waves bounce off a solid object. When waves reflect off rocks, they can create standing waves, which are waves that stay in one place. Standing waves can be very powerful and can cause erosion of the coastline.

* Refraction occurs when waves bend as they pass from one medium to another, such as from deep water to shallow water. When waves refract, they can be focused or spread out, depending on the shape of the coastline and the angle of the waves. Refraction can create areas of high wave energy, such as headlands, and areas of low wave energy, such as bays.

* Diffraction occurs when waves spread out as they pass through an opening, such as a gap between two rocks. Diffraction can create areas of high and low wave energy, depending on the size and shape of the opening.

The combined effects of rock structures and wave action can create a variety of coastal landforms, including:

* Beaches: Beaches are formed when waves deposit sediment on the shore. The size and shape of a beach depend on the amount of sediment available, the wave energy, and the tidal range.

* Headlands: Headlands are rocky points that extend into the ocean. They are formed by erosion from waves and currents.

* Bays: Bays are curved inlets of the coast. They are formed by waves and currents that erode the coastline.

* Estuaries: Estuaries are partially enclosed bodies of water where fresh water from rivers mixes with salt water from the ocean. They are formed by the drowning of river valleys by rising sea levels.