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Difficulty: HardInternal and External Structure of the Earth

The Earth's internal energy drives tectonic movements while external processes constantly reshape the lithosphere. Which of the following correctly identifies the semi-fluid internal layer that enables tectonic plate motion, alongside the external process responsible for the strictly in-situ disintegration of exposed surface rocks?

  1. Asthenosphere and weatheringAnswer
  2. B
    Lithosphere and mass wasting
  3. C
    Barysphere and metamorphism
  4. D
    Mesosphere and sedimentary deposition

Answer

Asthenosphere and weathering
The asthenosphere is the plastic, semi-fluid upper mantle region that permits lithospheric motion, while weathering is the external process responsible for the in-situ disintegration of rock material.

Step-by-Step Solution

1
Identify the internal structural layer responsible for plate mobility
The asthenosphere is the ductile, partially molten zone of the upper mantle (extending approximately 100 to 200 km beneath the surface) that allows overlying rigid plates to move.
Convection currents within the asthenosphere provide the mechanical drive for tectonic plate displacement.
2
Identify the external process defined by in-situ rock breakdown
Weathering is the static mechanical breakdown or chemical decay of rocks at their original location.
Unlike mass wasting or erosion, weathering involves no significant displacement or transport of material.

Key Concept

Internal mantle layers (asthenosphere) and external denudational processes (weathering)
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Topics

Internal and External Structure of the Earth

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