The energy of waves and longshore currents, as well as, to a lesser extent, tidal currents, continually modify shorelines. Longshore currents are formed when waves approach a coastline at an angle and are capable of eroding, transporting, and depositing. The direction of travel for longshore currents is indicated by the direction of the scarp, or high-tide line. Where scarping occurs, you can find rock outcroppings that were once part of the beach but now extend into the sea.
Where there are no waves, there are still tides. Tides are the water level changes caused by gravitational forces between the Earth and the Moon. The largest contributor to ocean tides is the effect of the moon, with other factors including those related to earth's rotation and mass also playing a role.
The highest tide of the month occurs on the night of the new moon, and the lowest on the night of the full moon. Tides follow a predictable pattern, with higher tides occurring as the moon gets closer to being full and lower tides happening as the moon goes through its phases.
As waves move toward the shore, their height decreases because the force of gravity increases as the square of the distance between two objects. This means that the waves will become smaller and smaller until they reach dry land. When a wave reaches land it breaks and creates a series of peaks and valleys.
The sediments will be spread down the shore by the waves, forming a beach. Waves also erode and transfer materials from cliffs and shorelines to beaches. As the seasons change, waves continuously transfer sand along the shore and sand from on-shore beaches to offshore sand bars. The combined action of waves and winds transports sediment and creates new land which eventually becomes part of a continent or island.
Waves are powerful agents that sculpt our coastlines. They can destroy as well as build, depending on the type of wave and the material being moved. Beach sands are constantly being moved by waves and deposited at another location. Beaches are never completely flat nor are they always smooth. They often have rock formations called "dunes" or "forests" where plants grow. Beach dunes help protect people and property from the force of wind and rain by reducing the impact of large forces against a small surface area. Beach forests are similar but instead of dunes there are trees growing in between the rocks that make up the beach.
Waves come in different shapes and sizes. There are long, straight-breaking waves, then there are short, breaking waves, and finally there are swells. Long, straight-breaking waves move away from the center of rotation (the storm) in one direction and then back again. These types of waves usually occur when there is a steady wind blowing in the same direction as the wave.
The beach varies throughout time due to continuous erosion of the shoreline by waves. This is terrain that protrudes from the coast and into the ocean, influencing how the adjacent shoreline erodes. Erosion by waves can also transport material from inland to sea-level, creating new material for future beaches. This process leaves a trail of destruction in its wake.
Beaches are constantly changing due to natural processes as well as human activity. Beach erosion is caused by different factors such as wind, water, ice, and gravity. Waves are responsible for nearly 70% of the total erosion on coastal beaches. The height of each wave increases as it approaches shore, causing greater amounts of sand to be swept away. As the water recedes, more sand is left behind. The amount of sand lost by erosion will eventually build up on another part of the beach. This creates a pattern of high and low tides on the shoreline. As long as enough sand is supplied by other sources (such as river sediment), then the area will not be affected by erosion.
If you look at a topographic map of your area, you should be able to see where most of the erosion has occurred. Areas with lots of erosion have been weathered down over time, while areas with less erosion remain untouched.
Over time, waves destroy the beach and push it further inland. More coastline is eroded when larger and stronger waves pound the shoreline, such as during a storm. The more frequently the water rises and falls, the more rapidly the beach is destroyed.
An increase in wave frequency will tend to move the most vulnerable part of the beach farther up onto the grass or inland, where it is protected from the waves. The amount of damage done to the beach by increased wave activity depends on the rate at which it erodes land that was previously dune-like habitat. If the rate of erosion is great enough, the whole beach may be destroyed within a few years. Otherwise, the beach will eventually be restored as new areas with dunes are formed behind the retreating edge.
Beaches are constantly changing shape due to natural processes like wind and water action as well as human activity. The impact of these changes on the surrounding environment depends on how the beach interacts with its environment. For example, if a beach becomes too narrow, then it can no longer protect itself against being overrun by high tides or storms. This leads to greater exposure to risk for people who live near the beach and also affects the wildlife that depends on the beach for shelter or breeding grounds.
Beaches are important for many reasons.
The coastline is influenced by waves (which are caused by wind at sea) and tides (produced by the gravitational effect of the moon and sun). Wind generates waves. The bigger the waves, the stronger the wind... So you can see that wind plays an important role in how the shoreline is shaped.
They are called "beach profiles". Beaches with steep drops off and high dunes have sharp waves. Low-lying beaches with gradual drops off and shallow water close to the shore have smooth waves. Between these two types of beach there are many others with wave shapes that change gradually from one end of the beach to the other or that have flat tops with no drop off at all.
The shape of a beach is mostly due to the action of waves breaking over the top of it. As waves break they lift sand up into mounds which then fall back down again. This moving and changing landscape causes more sand to be lifted up and dropped back down, which in turn changes the shape of the beach. For example, if a large amount of sand is lifted up onto a plateau then it cannot fall back down so the plateau will keep growing until it reaches the next rock formation or low-lying area of land. This is called "rock excavation" and the exposed rock will often welt (crater) like a lunar surface.