Landforms: Changes in Landform by Waves

Introduction to Landforms:

We all know that Earth is the third planet from the sun, and its surface is always changing. It is formed and reformed by water, wind, waves, and ice. These changes on land can take place quickly or slowly. Did you notice the power of waves anytime? Waves can change the beaches. If waves are too strong due to storms, then they may cause property damage, danger to living things, etc.

Fig. No. 1: Sea beach

Some landforms change in hours, such as mudslides quickly change hillsides. The majority of landforms take a long period of time to change. Running water, wind, waves, and ice change the landforms. These changes are due to weathering, erosion, and deposition.

Waves can collect a lot of sand, and that sand can be taken and deposited somewhere else, forming various landforms. In the process of collection of sand and deposition of sand, the size of the beach may decrease at one place, whereas it can grow at another place. In the period of the storm, powerful winds can cause very large waves that can wash away a large portion of a beach in a few hours.

Fig. No.2: Waves cause collection of sand

In this lesson, let us learn about the effect of waves on landforms. Weathering, erosion, and deposition cause changes to the land. 

Weathering is the process in which rock is broken down into smaller pieces by the effect of wind, water, and changes in temperature.
Erosion is the process in which weathered rock is transported from one place to another by wind, water, ice, or gravity.

Fig. No. 3: Weathering and erosion

Explanation:

Change in Landform by Waves

Over a period of time, the strong force of waves can change the shape of rocky cliffs. The waves constantly hit the cliffs and break large pieces of rock from the bottom of the cliff. Due to this constant action of waves on the cliff, the piece of cliff falls down. Waves then grind these rock pieces into smaller pieces of rock. This continues the activity of hitting of waves, the cliff erodes and becomes hollow at the base. So, when the top portion of the cliff is no longer supported by rock, it collapses and falls down, and the waves break down these rocks into smaller pieces. These smaller pieces get washed away by water, and this continuous activity of erosion and weathering makes the rocky cliffs smaller and smaller.

Fig. No. 4: Erosion and weathering of rocky cliffs

Formation of Sea Arch:

In the beginning, the softer rock on the side of the coastline erodes, and sometimes waves can also erode and create a hollow area termed as a sea cave. Due to the action of erosion, the base of the cliff erodes so much that the rock present above the cliff collapses and creates a wave-cut cliff.

One more landform created by continuous erosion by waves is called a sea arch. A sea arch forms when a layer of soft rock present under hard rock gets eroded by waves. If a sea arch collapses due to erosion, it forms a large stack of rock in the middle of the water called a sea stack.

Fig. No. 5: Formation of sea arch due to erosion and weathering

Barrier Islands:

Barrier islands are long and narrow pieces of land formed by the deposition of sand. These islands run parallel to the coast and form a barrier between the coast and the ocean. The advantage of a barrier island is that it protects the coastline from erosion. The majority of the eastern states in the United States have barrier islands. Waves erode and deposit sediments on the side of the island that faces the open ocean; these islands are reshaped by oceanic waves. Water that faces the coast also changes the island, and this water brings the sand to the island. On barrier islands, the side facing the coast gets built up, whereas the other side gets eroded. Beaches, spits, sandbars, and barrier beaches are formed by the deposition of sediments.

Spits: A spit is a long beach that appears in the water.

Sandbars form when incoming waves deposit (accumulate) their sediment before the waves get to the beach.

Barrier beach: When waves collect large amounts of sand above sea level, they form barrier beaches. It is a long narrow island.

Fig. No.6: Barrier island, spits, sandbar

Summary:

• Natural features on Earth’s surface are called landforms.
• Waves can change the beaches.
• The strong force of waves can change the shape of rocky cliffs.
• A sea arch forms when a layer of soft rock present under hard rock gets eroded by waves.
• When a sea arch collapses due to erosion, it leaves a large stack of rock in the middle of the water called a sea stack.
• Beaches, spits, sandbars, and barrier beaches are formed by the deposition of sediments.