How Waves Shape Coastlines

Waves are movements of water that travel across the ocean's surface. When waves reach the shore, they crash against the land with great force. This constant pounding does important work—it changes the shape of coastlines.

Ocean waves cause erosion, which means they wear away rock and sand. As waves hit cliffs, they break off small pieces of rock. Over many years, waves can carve tall cliffs and create sea caves—hollow spaces in the rock where waves have worn away softer materials. Waves work like sandpaper rubbing against wood, slowly wearing it down bit by bit.

Waves also move sand and sediment along the coast. This process is called deposition, which means waves pick up sand from one place and drop it somewhere else. A wave might take sand from a cliff and carry it down the beach. This is why beaches are always changing shape. Some areas lose sand while other areas gain it.

During storms, waves become much more powerful. Storm waves can erode large amounts of land very quickly, sometimes washing away entire sections of beach in just one day. Because waves never stop moving, coastlines today look different than they did hundreds of years ago, and they will continue to change in the future.

Interesting Fact: The White Cliffs of Dover in England are shrinking by about one centimeter each year because waves constantly crash against them and wear away the soft chalk rock!