1. Hydraulic Action: The sheer force of waves crashing against cliffs and rocks creates pressure. This pressure can force air into cracks and crevices, which then compresses and expands as waves retreat, causing the rock to break apart.

2. Abrasion: This is the process of rocks and pebbles being carried by waves grinding against cliffs and rock surfaces. This acts like sandpaper, wearing away the rock over time.

3. Corrosion: This involves the chemical breakdown of rock by seawater. Saltwater is slightly acidic and can dissolve certain types of rock, particularly limestone and chalk. This process is accelerated by the presence of organisms that release acids.

4. Attrition: This is the process of rocks and pebbles colliding with each other as they are moved by waves. This continuous grinding breaks down the rocks into smaller and smoother fragments.

These processes work together to shape the coastline, creating features like cliffs, caves, arches, and stacks.