A beach is a landform that extends along a body of water. While beaches at the ocean are common, they can also be found at lakes and rivers. Beaches are created by waves that erode rocks and carry sand and other sediments into the water. Beaches can be made up of sand, pebbles, or other large stones. Beaches are often lined with trees or other vegetation that provides protection from wind and waves. In addition to their natural beauty, beaches offer recreational opportunities like swimming, sunbathing, and building sandcastles.
Beaches are constantly changing, even within the course of a single day. A beach may destroy itself and then rebuild itself, bringing in new materials and taking away others. This constant change is what makes beaches so fascinating.
One of the most important factors that contributes to beach formation is weathering, the process by which rocks are broken down into smaller pieces. Some minerals, such as quartz and feldspar, are harder than others. Over time, these rocks rub against each other, creating sand. As the sand is worn away, it becomes finer and softer. Beach sand is mostly made up of minerals from land, but some comes from marine organisms. Shells and other hard parts of dead organisms wash up on shore, where pounding waves break them down into smaller sand-sized particles. In areas with volcanoes, sand on beaches may come from volcanic rock. Beaches at these locations often have distinctive colors, with red beaches containing lots of iron, green beaches containing olivine, and black beaches consisting of obsidian.
The other major factor that affects beach creation is erosion. The swirling turbulence of breaking waves excavates a trough on the beach. The sand that washes into this trough is carried back out to sea in the form of a rip current. This sand is deposited offshore, where it builds a bar. The shape of a bar depends on the size and strength of the waves that create it. It is usually crescent-shaped, with its concave side facing the water.
When a beach is eroded away, it exposes deeper sediments. These deposits sometimes include fossils, animal remains, and even human artifacts. Coastal erosion is usually slow and gradual, but it can be very rapid in some places. Beaches may also be affected by storm surges and high tides.
A wide variety of animals live on or near beaches. Crabs and other crustaceans feed on the sand, shellfish hunt in the surf, and birds nest and lay eggs on beaches. Plants like beach grass and seaweed thrive in dunes and on the sand itself. Beach pollution, however, can harm wildlife. Plastic debris can choke or tangle up sea creatures, and trash can prevent algae and other plants from growing on the sand or in the water. It is important to reduce beach pollution and leave all wildlife alone.