The materials that make up a beach may be carried long distances by the wind and waves. This sediment may contain sand, shells, and seaweed, and the ocean currents can carry it hundreds of kilometers away. This is one of the main ways that beaches are formed. These currents transport sand and other debris to the coast, and they change beaches every day.
A beach can be a long stretch of land, or it may be a stretch of sand that is a part of a lake or large river. The ridges form as the water flows up the shore. Beaches vary in their heights, with the higher the ridges, the greater the water sand absorption.
While beaches vary greatly in size, shape, and nature, they all have unique features and characteristics. Some are steep, wide, or gentle. Others are rocky or arid. Some are even populated with sea turtles! While most beaches contain shells, others have little or no shell content at all. In addition, beaches change width over time, often due to a force of nature that cannot be seen. If you spend time exploring the beach, you may notice tree stumps, mud layers, rocks, and other features that make the area unique.
Beaches can also have a berm or a low tide bar, which are both structures that help preserve the beach’s profile. The berms create low-energy areas that break waves, and they move sediment back to the sea during high-water periods. In addition, there can be long shore bars and troughs, which make the beach’s profile more flat.
Sand particles are also shaped by wave action. Waves push sand 30 to 50 feet into the ocean, but this sediment is then pushed back to the shelf during storms. Sand bars and tidal deltas are also important sources of sand for many beaches. Bluffs and headlands can also contribute sand to the coast.
The sand on a beach is usually a combination of pebbles and rock fragments. The latter is often derived from volcanic rock. For instance, red beaches have volcanic rocks rich in iron. Green beaches, on the other hand, have volcanic rocks rich in olivine, and black beaches are made of obsidian, a volcanic glass. In the past, lava flowing into the ocean has turned into obsidian, and the waves smooth out the shards to make sand. Some sand also comes from ocean debris, as the waves beat down cliffs.
The composition of a beach is dependent on the types of sediments that are upstream. These sediments are blown down by winds and moving water, affecting the particle size, state of compaction, and even the length of time between crests. If the sediments are compacted, they will be more resistant to erosion. However, sediments in suspension are more vulnerable to erosion by longshore currents and waves.