Which one of the following best describes the Lithosphere?
- (a)Upper and lower mantle
- (b)Crust and core
- (c)Crust and upper mantle
- (d)Lower mantle and core
Correct — C, Crust and upper mantle. The lithosphere is the Earth's rigid outer shell — it comprises the crust together with the uppermost, solid part of the upper mantle. This brittle layer is broken into the tectonic plates that move over the weaker, partly molten asthenosphere beneath it. It typically reaches down about 100 km, though it is thinnest under the oceans and thickest beneath old mountain belts.
- (a)Upper and lower mantle — The lithosphere is only the rigid top of the upper mantle plus the crust, not the whole mantle; the lower mantle lies far below it.
- (b)Crust and core — The core sits at the Earth's centre, thousands of kilometres down, and is not part of the lithosphere.
- (d)Lower mantle and core — Both the lower mantle and the core are deep interior zones, well beneath the rigid lithosphere.
The Earth's interior is layered into crust, mantle and core. The lithosphere is a mechanical layer — the rigid crust plus the solid uppermost mantle — that behaves as a single brittle shell and is fragmented into tectonic plates. Below it lies the plastic asthenosphere, over which the plates slide.
The trap is confusing the chemical layers (crust, mantle, core) with the mechanical layers (lithosphere, asthenosphere). The lithosphere cuts across the crust-mantle boundary, taking the crust and just the top of the mantle, so 'crust and upper mantle' is the best description.
- The lithosphere is the rigid outer shell made of the crust and the uppermost solid mantle.
- It is broken into tectonic plates that move over the asthenosphere.
- It is generally about 100 km thick, thinner under oceans and thicker under continents.
- The asthenosphere below is weaker and partly molten, which allows plate movement.
The lithosphere is the crust plus the uppermost solid mantle — option (c).
- Equating the lithosphere with the whole mantle — it is only the rigid top of the upper mantle plus the crust.
- Mixing the chemical layers (crust, mantle, core) with the mechanical layers (lithosphere, asthenosphere).
Asked as a definition of the lithosphere or by contrasting it with the asthenosphere.
No directly related past PYQ was found.
- practice — not a real PYQ
The tectonic plates form part of which layer of the Earth?
- (a)Asthenosphere
- (b)Lithosphere
- (c)Outer core
- (d)Lower mantle
Answer(b) Lithosphere — the rigid crust and uppermost mantle.
- practice — not a real PYQ
The layer immediately below the lithosphere, over which the plates move, is the
- (a)inner core
- (b)asthenosphere
- (c)crust
- (d)outer core
Answer(b) asthenosphere.