The three main processes of wave erosion are abrasion, attrition, and hydraulic action.
Wave erosion is a powerful force constantly reshaping coastlines. It is predominantly carried out by destructive waves, which possess high energy and a strong backwash that pulls material away from the shore. According to the provided reference, within these destructive waves, there are three main types of erosional processes taking place: abrasion, attrition and hydraulic action. These processes work together to erode coastal materials and create distinct landforms.
Let's explore these processes in more detail.
The Three Main Wave Erosion Processes
1. Hydraulic Action
This is often the initial and most powerful erosional process. Hydraulic action occurs when the sheer force of moving water and the pressure it exerts on the coastline erodes material.
- How it works: Waves crash against cliffs and rock faces, forcing water into cracks and crevices. The air trapped in these spaces becomes compressed by the incoming wave. As the wave retreats, the pressure is suddenly released, causing the trapped air to expand violently. This rapid compression and expansion weakens and breaks down the rock over time, potentially dislodging pieces.
- Impact: Causes rock to fracture and break away.
2. Abrasion (Corrasion)
Abrasion is like the sandpaper effect of the sea. It involves the grinding and scraping action of the sediment and rocks carried by waves against the coastline.
- How it works: As waves move, they pick up pebbles, sand, and other debris. These materials are hurled against the cliffs and shore platforms. This constant impact and friction wears away the rock surface, much like using sandpaper on wood.
- Impact: Grinds down and polishes rock surfaces, creating platforms and notches at the base of cliffs.
3. Attrition
Attrition is the process where the rock fragments and pebbles carried by waves collide with each other. This process doesn't directly erode the coastline itself but breaks down the material being transported.
- How it works: Rock particles and sediment within the waves are constantly jostled, bounced, and crashed into one another. This causes them to become smaller, rounder, and smoother over time.
- Impact: Reduces the size and increases the roundness of beach material and sediment, making it easier for waves to transport.
Summarizing the Wave Erosion Processes
The reference notes that these processes create different coastal erosion landforms. Below is a summary table outlining the three processes:
| Process | Description | How it Erodes |
|---|---|---|
| Hydraulic Action | The force of water and trapped air pressure within cracks. | Water and air compressed into rock fractures weaken and break rock. |
| Abrasion | Sediment and rocks carried by waves grinding against the coastline. | Carried material scrapes and wears away rock surfaces. |
| Attrition | Rock fragments and pebbles within the waves colliding with each other. | Sediment impacts itself, breaking into smaller, rounder pieces. |
These processes are interlinked; for example, hydraulic action might create cracks where abrasion can then become more effective, and attrition breaks down the material that is causing abrasion. Together, they are the primary mechanisms by which waves carve out the diverse shapes of our coastlines.
