Agents of landforms change

Agents of landforms change

Landforms

          Different types of landforms are found on our earth because its surface is not uniform. These landforms have been created by internal and external forces of the earth-Mountains, plateaus and plains etc. are the major landforms created by the internal forces of the earth. External forces of the earth include different agents which create different landforms in different environments by erosion and deposition. These agents are river, glacier, wind and sea waves etc.

          Let us have a look on landforms created by these agents.

Landforms Made by River

          River is an important agent of landform change. Permanent rivers are found in those areas which receive ample rainfall regularly presence of mountains provides initial slope for the flow of surface water in tiny channels. These tiny channels join to form a river. A river after its creation performs three types of geologic work. It breaks the rocks coming in its way. This act is called Erosion. It transports the eroded material. This act is called Transportation. It deposits the eroded material when its speed is very low. This act is called deposition.

1. River’s Emotional landforms

          In mountains the valley of the river gets deeper due to downward erosion and attains the shape of English alphabet ‘V’. This landform is called V-Shaped valley. Very deep valleys are often called ‘Gorges or canyons’. Such valleys are found in northern areas of Pakistan.

2. Water fall

          River bed may contain hard and soft rocks. Sometimes soft rocks are found beneath hard rocks. When the river cuts the upper layer of hard rocks on the ved, it tends to erode the lower hard rocks to a great depth. This results in the creation of water fall.

3.      Pot Holes

          Sometimes the swirling action of stones in the water develops holes in the river bed. These are called potholes.

4.      Meanders and ox-bow lake

          Occurrence of hard and soft rocks in the river’s channel results in the creation of a winding path due to uneven erosion of the river. These are called meanders. Sometimes river after cutting the outer bends of the meanders attains a straighter channel, leaving behind a crescent lake at the side. This lake is called Ox- bow lake. Kalery lake on river Indus is an ox-bow lake.