Erosion by Waves: Landforms and Types

Key Concepts

• Erosion

Introduction: 

We all know that Earth is a third planet from the sun, and its surface is always changing. It is formed and reformed by water, wind and ice. These changes on land can take place quickly or slowly. When we travel by airplane, we see big mountains, deep valleys, rivers, ice sheets, desert areas, beaches along shorelines, and plains. Mountains, valleys, rivers, and plains are some of the natural features on Earth’s surface. These natural features on Earth’s surface are called landforms. 

Some landforms change in hours, such as mudslides which quickly change hillsides. The majority of landforms take a long period of time to change. The landform, as shown in Fig. no. 1 took millions of years to form. Fast moving water changed the land under the Colorado River. The river carried away the sediments, and by this activity, the river bed became deeper, and eventually, the river carved a canyon. The canyon is a deep, narrow valley with steep sides and often has rivers at the bottom. Running water, wind, waves, and ice change the landforms. These changes are due to weathering, erosion, and deposition. 

A canyon is a structure with a deep, narrow valley and steep sides.  Generally, rivers are present at the bottom of the Canyons. In this lesson, let us learn about the effect of running water, waves, wind, and ice in the change of 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 change in temperature. 

Erosion is the process in which weathered rock is transported from one place to another by wind, water, ice, or gravity. 

     

Change in landform by water 

When the rainwater does not get soaked into the ground, it starts flowing downhill. As rainwater flows, it forms a channel and flows into streams and rivers. The water flows from mountains to the sea, i.e., from the top (mountain) to the bottom (sea). The running water changes the land present on the sides and at the bottom of the streams and rivers. 

For example: In high mountains, rain falls and the snow present on mountains and on land melts; the water starts to come downwards. When water starts hitting the downhill journey, it forms streams, and when these streams join, they form small rivers. As the river starts its downhill journey, it cuts away land present on their sides and carries small rocks, sand (sediments). This leads to the formation of a valley. In high mountains, the rivers cut in ‘V’-shaped deep valleys. 

Rivers Curve: 

When water moves continuously downhill from a mountain, the land becomes flat, and the river flows a bit slower and becomes wider. The river erodes land on one side and deposits sediments on the other side. This erosion and deposition cause the river to develop curves. Older rivers form very broad, looping curves and over a period of time, the curves of the river change. 

Formation of delta: 

River water flows and meets into other rivers, and eventually, all river water flows and combines with the ocean. Here, the river flows very slowly and drops sediments that have been carried from long distances into the river. These sediments form an area of land near the mouth of the river that is known as the delta.  

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.