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Difficulty: HardEarth's Interior and Plate Tectonics

Earth's interior is differentiated into distinct mechanical layers characterized by differing physical states, densities, and responses to tectonic stress. What is the correct sequence of these mechanical layers from Earth's outermost surface down to its center?

  1. 1Lithosphere: the brittle, rigid outer layer composed of the crust and uppermost solid mantle
  2. 2Asthenosphere: the ductile, semi-fluid upper mantle region that enables tectonic plate movement
  3. 3Mesosphere: the rigid, high-density lower mantle extending down to the outer core boundary
  4. 4Outer Core: the liquid layer of molten iron and nickel responsible for generating Earth's magnetic field
  5. 5Inner Core: the solid, dense metallic sphere under extreme pressure at the planet's center

Answer

Arranged from Earth's outermost surface to its center, the correct order is the Lithosphere, followed by the Asthenosphere, Mesosphere, Outer Core, and Inner Core.
Earth's mechanical layers progress inwards from the surface to the center based on depth and physical properties: the rigid Lithosphere (0–100 km), ductile Asthenosphere (100–660 km), solid Mesosphere (660–2,900 km), liquid Outer Core (2,900–5,150 km), and solid Inner Core (5,150–6,371 km).

Step-by-Step Solution

1
Identify the topmost brittle layer at Earth's surface.
The lithosphere forms the rigid exterior shell containing tectonic plates.
Because it encompasses the crust and uppermost mantle, it is position 1 at the surface.
2
Identify the plastic upper mantle layer directly underlying the lithosphere.
The asthenosphere is located in the upper mantle beneath the brittle lithosphere.
High temperatures allow solid-state flow in this layer, facilitating continental drift.
3
Identify the lower mantle layer beneath the asthenosphere.
The mesosphere (lower mantle) extends from the base of the asthenosphere to the core-mantle boundary.
Immense pressure keeps the lower mantle solid despite elevated temperatures.
4
Identify the liquid metallic layer beneath the lower mantle.
The outer core is situated directly beneath the mantle.
Temperatures at this depth exceed the melting point of the iron-nickel alloy at prevailing pressures.
5
Identify the central core sphere at the center of the planet.
The inner core forms the center of Earth.
Extreme confining pressure forces the iron-nickel core into a solid state despite extreme temperatures.

Key Concept

Earth's internal mechanical layers are organized by increasing depth and density from surface to center: lithosphere, asthenosphere, mesosphere, outer core, and inner core.
Estimated Time:1m 30s
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Topics

Earth's Interior and Plate Tectonics

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