Our Changing Earth (Basic)

Major Land Forms

The surface of the Earth is not flat. It is uneven with various physical features called landforms. These are primarily formed by internal and external forces.

Major landforms include:

• Mountains: Elevated parts of the Earth's surface formed by tectonic forces.
• Plateaus: Flat-topped tablelands that are raised above the surrounding areas.
• Plains: Low-lying, flat areas formed by river deposits. These are fertile and suitable for agriculture.

These landforms are constantly being modified by natural agents like rivers, wind, glaciers, and sea waves.

Work Of A River

Rivers play a major role in shaping the landscape. Their work includes:

• Erosion: Rivers wear away the land and form valleys and waterfalls.
• Transportation: Rivers carry eroded materials like silt, sand, and pebbles downstream.
• Deposition: The river deposits these materials, forming landforms such as floodplains, levees, and deltas.

Work Of Sea Waves

Sea waves constantly strike the coast and perform the following functions:

• Erosion: They erode rocks and cliffs to form features like sea caves, arches, and stacks.
• Deposition: Materials carried by waves get deposited to form beaches and sandbars.

Work Of Ice

Glaciers, or moving masses of ice, shape the land through:

• Erosion: Glaciers erode soil and rock to form U-shaped valleys and fjords.
• Deposition: When glaciers melt, they deposit debris to form moraines and drumlins.

Work Of Wind

Wind is a powerful agent in arid regions and deserts. It performs:

• Erosion: Wind erodes soft rocks, forming mushroom rocks and yardangs.
• Deposition: It deposits sand to form dunes and loess plains.

Thus, various agents continuously reshape the Earth’s surface over time.