The layer of the upper mantle over which the tectonic plates move is known as the
- A.Lithosphere
- B.Asthenosphere
- C.Barysphere
- D.Biosphere
Correct answer
Explanation
The correct answer is B, the asthenosphere. It lies in the upper mantle just below the rigid outer shell, is weak and partly molten, and is the main source of the magma that reaches the surface through volcanoes; the plates slide over it.
Option A, the lithosphere, is that rigid outer shell itself, made of the crust plus the solid uppermost mantle, and it is what the plates are made of rather than what they move on. Option C, the barysphere, is an older term for the heavy central part of the Earth, that is the core. Option D, the biosphere, is the zone of life where land, water and air meet, and has nothing to do with the interior. The pair lithosphere and asthenosphere is the trap here, so fix the idea that the rigid one rides on the weak one.
Read the full article: Structure of the Earth and Rocks: Layers, Waves and Types
Practice Questions
View allThe boundary that separates the crust from the mantle is known as the
- A.Conrad discontinuity
- B.Mohorovicic discontinuity
- C.Gutenberg discontinuity
- D.Lehmann discontinuity
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Named after the Croatian seismologist who noticed that earthquake waves suddenly speed up at a certain depth, it marks the base of the crust and the top of the mantle, and is commonly shortened to the Moho.
Read the full explanation →Which of the following seismic waves cannot travel through liquids?
- A.Primary or P waves
- B.Secondary or S waves
- C.Surface or L waves
- D.All three types
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They are transverse waves, in which particles vibrate at right angles to the direction of travel, and such motion cannot be sustained in a fluid, so S waves die out at the outer core.
Read the full explanation →Marble is a metamorphic rock formed from which of the following parent rocks?
- A.Sandstone
- B.Shale
- C.Limestone
- D.Granite
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Limestone is a sedimentary rock made largely of calcium carbonate, and when heat and pressure recrystallise it without melting it, the result is marble, the stone used in the Taj Mahal and in the Dilwara temples.
Read the full explanation →The Deccan Trap of peninsular India is composed mainly of which rock?
- A.Granite
- B.Basalt
- C.Limestone
- D.Gneiss
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The Deccan Trap was formed by vast fissure eruptions in which lava spread over the surface and cooled quickly, giving a fine-grained extrusive igneous rock, basalt.
Read the full explanation →Fossils of ancient plants and animals are found mainly in which type of rock?
- A.Igneous rocks
- B.Sedimentary rocks
- C.Metamorphic rocks
- D.Plutonic rocks
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They are built up layer by layer as sediment settles over the remains of living things and hardens gently, so shells, bones and plant matter survive as fossils.
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