• Cliffs and caves are features formed by coastal erosion.bretagne image by Zeno from Fotolia.com
  
  Ocean waves, tides and current exert a tremendous erosive force on the coastline through abrasion from materials in the water, corrosion from the carbonic acid in seawater and simple hydraulic pressure. In addition to the effect of the sea, wind, rain, frost and human activity also erode coastlines. These erosive processes produce several distinctive features or landforms including wave-cut cliffs and platforms, headlands and bays, caves, arches, stacks and stumps.
  
  

Wave-Cut Cliffs and Platforms

• Cliffs are the most common feature caused by coastal erosion. Coastal cliffs are steep rock faces that form along coastlines from erosion-resistant rocks. The waves strike the base of the cliff, undercutting it until the top collapses. As this process continues, the face of the cliff slowly retreats inland, getting steeper the farther inland it goes.
  
  A wave-cut platform is formed at the base of the cliff. It is a gradual sloping ramp out of the sea to the base of the cliff formed in large part by the debris that has fallen from the cliff as it retreats inland. The platform is usually submerged except at low-tide.
  
  

Headlands and Bays

• A headland is a point of land or promontory that juts out into the sea. A bay is the opposite of a headland; it is an indentation into the coastline. Headlands and bays form along coastlines where bands of soft rock alternate with relatively erosive-resistant rock. The soft material erodes more quickly than the hard, forming bays. The exposed headlands jut out on either side of the bay and shelter them from some of the erosive forces, reducing the difference in the rate of erosion of the two bands of rock.
  
  

Caves, Arches, Stacks and Stumps

• Sea arches are a result of erosion by wave action.arche sur la plage image by MONIQUE POUZET from Fotolia.com
  
  Wave action pounding the cliff face erodes areas of soft or weakened rocks and gradually forms a cave. As the cave deepens, it may eventually grow into the back of another cave, leaving an arch. An arch is essentially two pillars connected at the top by a bridge. Continued erosion can cause the top of the arch to collapse, leaving a pillar of rock called a stack. The stack itself continues to erode until it becomes so short that it is covered at high tide. It is then called a stump.