A wave is an up-and-down movement of water. When wind blows over the ocean, waves are formed. Tides, storms, and earthquakes also cause ocean waves. The force of breaking waves, or waves striking the shoreline, can break rocks into small pieces. They grind against one another and wear down rock particles until they become sand. Waves can carry this sand away.
Salt water from the ocean gets into the cracks and can also break down rocks into smaller pieces.
The following are features which are formed due to wave erosion
- Wave- cut platforms. When the cliff steepens as the weathering attacks the base further, the cliff retreats, and the rock debris is swept by the backwash creating a -. – are shaped through the process of erosion.
- Caves. Holes in the cliff face are enlarged by the wave erosion, and tunnel like openings are formed called caves. A cave is formed firstly by a cliff. The sea attacks the cliff and begins to erode the area of weakness such as the joints and cracks through the procedures of hydraulic action, wave pounding, abrasion and solution.
- Arches. is created when a cave in a headland is eroded right through i.e. the inlet has two openings. An arch is formed when a cave is eroded, and where the fault lines run through the headlands, two caves will eventually erode into the back of each other forming an arch, passing right through a headland.
- Stacks. When the arch collapses a pillar of rock remains behind as a sea stack. Stacks can be found close to cliff, where there is a high wave action. The way a stack is formed is when an arch collapses, leaving a stand of a boulder there
- Headlands. are formed in areas of alternating resistant and less resistant rocks. Erosion/wave action acts less on the more resistant rock creating headlands. Headlands are formed due to the presence of both soft and hard rocks. Because of this differential erosion occurs, with the soft, less resistant rock (e.g shale), eroding quicker than the hard resistant rocks (e.g chalk). Where the erosion of the sot rock is rapid, bays are formed. Where the is more resistant rocks, erosion is slower and the harder rocks are left to be sticking out into the sea as a headland.
- Blow hole. A blowhole forms in a cave. As a cave moves inland, the roof above it is weakened and as waves crash into the cave, they can be reflected upwards, eroding the roof of the cave. At the same time, weathering on the roof of the cave will help weaken it further and eventually water will be able to break through it, leaving a blowhole.
- Bays are indents in the coastline between two headlands. Bays are also formed in areas of alternating resistant and less resistant rocks. Erosion/wave action acts more on the less resistant rock creating bays. Where the erosion of the soft rocks is more rapid, bays are formed.
- Off-shore terrace. A wave- built terrace is the offshore zone composed of gravel and coarse sand. The base of the cliff forms the wave-cut platform as attrition (form of coastal or river erosion)causes the collapsed material to be broken down into smaller pieces, while some cliff material may be washed into the sea.
- Stump. The stack will be attacked at the base in the same way that a wave-cut notch is formed. This weakens the structure and it will eventually collapse to form a stump.
- cliffs. are steep rock faces along the coastline, they tend form along concordant coastlines with resistant rocks parallel to the coast. The erosion of a cliff is greatest at it’s base where large waves using actions such as hydraulic action, scouring and wave pounding actively undercut the foot of the cliff forming an indent called a notch, is cut by waves at high tide level and developed further, as this notch develops, a cliff is formed.