How Are Beaches Formed?

How is a Beach Born?

A day at the beach is one of the most relaxing and enjoyable things in the world. Since prehistoric times people have been drawn to the sandy coastlines for both sustenance and recreation, and for an undoubtedly equally long period they have wondered how a beach comes to be in the first place. If you've ever looked at a grain of sand up close, you may have though that it resembled a tiny rock. As it turns out, that's all a grain of sand really is.

Erosion and Deposition

Beaches are a prime example of what is called a deposition landform, meaning they are built up over time by the addition of sediment. Sediment is a term for particles of rock or earth produced from larger particles over time. The weathering of rocks by wind, rain, ice and geological processes causes their breakdown into smaller units, which then undergo a process known as erosion.

When erosion occurs, sediment is transported from one place to another by gravity, wind, glacier movement or flowing water. Certain causes of erosion, such as a river, tend to transport a large amount of their sediment to a common location, such as the point where the river joins a larger body of water. Over time the sediment may accumulate and produce a new land form, such as a dune, sand bar or beach.

Waves, Deltas and Beach Formation

In the case of the beach, ocean waves are usually responsible for most of the deposition. Offshore rocks and coral reefs gradually erode due to the action of currents, producing sediment which is deposited when the waves crash into the shoreline. However, this sediment is not always in the form of sand. Gravel, pebbles and shell fragments are just a few of the other types of sediment often deposited on a shoreline. Human recreation tends to focus on the sandier sites, but there are other types of beaches as well.

Rivers may also be involved in this process. The point where a river drains into an ocean is called a delta, and at these places deposition can occur on a massive scale. Deltas are often extremely fertile farmland because of this, and for the same reason they are also home to many of the world's most popular beaches.

The sand at such sites may have been moved thousands of miles from the interior of a continent by a river's current, until it was lain on top of sand drawn up from the dark depths of the ocean.