Shaping of the Earth’s Surface
Short Questions
1. What is the Earth’s outermost layer called?
Answer: The Earth’s outermost layer is called the crust.
2. Which layer lies below the crust?
Answer: The mantle lies below the crust.
3. Which is the innermost layer of the Earth?
Answer: The core is the innermost layer of the Earth.
4. What are the three main types of tectonic plates?
Answer: Continental plates, oceanic plates, and mixed plates.
5. What is the Mid-Atlantic Ridge an example of?
Answer: It is an example of a divergent plate boundary.
6. What happens when an oceanic plate collides with a continental plate?
Answer: The oceanic plate sinks beneath the continental plate, causing volcanoes and earthquakes.
7. What is the main cause of convection currents in the mantle?
Answer: Heat from the Earth’s core causes convection currents.
8. Why is the theory of plate tectonics important?
Answer: It explains the formation of landforms and natural disasters like earthquakes and volcanoes.
9. What is chemical weathering?
Answer: Chemical weathering is the breaking down of rocks by reactions with water, air, or acids.
10. Which type of weathering is caused by plant roots?
Answer: Biological weathering.
11. Which type of erosion is common in dry and sandy areas?
Answer: Wind erosion.
12. Which natural agent forms caves and sinkholes?
Answer: Groundwater.
13. What is a waterfall?
Answer: A waterfall is a place where a river falls over a steep cliff or vertical drop.
14. What is a meander?
Answer: A meander is a winding bend in the middle or lower course of a river.
15. Where is a delta formed?
Answer: A delta is formed at the mouth of a river where it enters a sea, ocean, or lake.
Long Questions
1. Explain the structure of the Earth.
Answer: The Earth has three main layers: the crust, mantle, and core. The crust is the outermost layer where we live. Below it is the hot and thick mantle. The core is the innermost layer and is extremely hot and heavy. The crust and the upper mantle together form the lithosphere, while the semi-molten asthenosphere below allows tectonic plates to move.
2. Explain the three types of plate boundaries.
Answer: There are three types of plate boundaries. At a convergent boundary, two plates move towards each other and may form mountains or volcanoes. At a divergent boundary, plates move apart and new crust is formed. At a transform boundary, plates slide past each other, mainly causing earthquakes.
3. How does plate tectonics shape the Earth’s surface?
Answer: Plate tectonics causes the movement of the Earth’s crust. This movement forms mountains, valleys, volcanoes, ocean basins, and causes earthquakes. It also explains the present distribution of continents and oceans and helps identify earthquake- and volcano-prone regions.
4. Explain the difference between weathering and erosion.
Answer: Weathering is the breaking of rocks into smaller pieces without moving them. Erosion is the wearing away and movement of soil and rocks by water, wind, ice, or waves. Weathering breaks the rocks, while erosion carries the broken materials from one place to another.
5. Describe the different types of weathering.
Answer: There are three types of weathering. Physical weathering breaks rocks due to temperature changes, frost, or wind. Chemical weathering changes the minerals in rocks through reactions with water, air, or acids. Biological weathering is caused by plants, animals, and micro-organisms, such as plant roots breaking rocks.
6. How does erosion affect human life?
Answer: Erosion removes fertile topsoil, reducing crop production. It can wash away land, roads, and houses near rivers and coasts. It also creates safety problems in construction and mining and affects tourism and fishing by damaging beaches, rivers, and fertile land.
7. How do rivers shape the Earth’s surface?
Answer: Rivers shape the land by erosion, transportation, and deposition. In the upper course, they form V-shaped valleys and waterfalls. In the middle course, they form meanders and floodplains. In the lower course, they form deltas, levees, and alluvial fans through the deposition of sediments.
8. Why are deltas important for humans?
Answer: Deltas have fertile alluvial soil that is suitable for farming crops like rice and jute. They support fishing because of rich aquatic life. Many people live in deltas, and rivers provide routes for trade and transportation. However, deltas are also prone to flooding.
9. Explain the importance of beaches.
Answer:Beaches are formed by the deposition of sand, pebbles, and rocks along the coast. They are popular tourist places for recreation and swimming. They support fishing, provide materials like sand and shells, and protect coastal settlements by acting as natural barriers against strong waves and coastal erosion.
10. How do glaciers benefit human life?
Answer: Glaciers create U-shaped valleys, cirques, hanging valleys, and fjords. These landforms attract tourists for trekking, skiing, and mountaineering. Glaciers provide fresh water to rivers, support agriculture through fertile glacial soil, and help create natural lakes and water resources.
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