Lithosphere consists of
- (a)upper and lower mantle.
- (b)crust and core.
- (c)crust and uppermost solid mantle.
- (d)mantle and core.
Correct — C, crust and uppermost solid mantle. The lithosphere is the rigid outer shell of the Earth. It is not just the crust: it is the crust welded to the topmost, rigid part of the upper mantle, and this combined solid layer rests on the weaker, partially molten asthenosphere below. It is this crust-plus-uppermost-mantle shell that is fragmented into the tectonic plates.
- (a)upper and lower mantle. — The upper and lower mantle together make up the mantle; only the rigid topmost sliver of the upper mantle joins the crust to form the lithosphere.
- (b)crust and core. — The core lies far below, separated from the crust by the entire mantle; it is not part of the lithosphere.
- (d)mantle and core. — This omits the crust and wrongly includes the deep core; the lithosphere is a shallow crust-and-uppermost-mantle layer.
Earth can be divided chemically into crust, mantle and core, but mechanically the outer part splits into a rigid lithosphere over a plastic asthenosphere. The lithosphere is the crust plus the uppermost, brittle part of the upper mantle — the layer that behaves as rigid tectonic plates.
The trap is to equate 'lithosphere' with 'crust' or to reach for the deep core. The key idea is that the lithosphere crosses the crust-mantle boundary: it is crust plus the solid top of the mantle, sitting above the softer asthenosphere.
- The lithosphere is the rigid crust plus the uppermost solid part of the upper mantle.
- It overlies the asthenosphere, a weaker, partially molten layer of the upper mantle.
- The lithosphere is broken into the tectonic plates that drift over the asthenosphere.
- Chemical layers (crust, mantle, core) differ from mechanical layers (lithosphere, asthenosphere, etc.).
Lithosphere = crust + uppermost solid mantle, resting on the plastic asthenosphere.
- Equating the lithosphere with the crust alone — it also includes the rigid top of the mantle.
- Including the core, which lies far below the lithosphere.
Definition item on Earth's layers, or matching each layer (lithosphere, asthenosphere, core) to its composition and behaviour.
No directly related past PYQ was found.
- practice — not a real PYQ
The lithosphere rests directly on which weaker, partially molten layer?
- (a)Outer core
- (b)Asthenosphere
- (c)Inner core
- (d)Lower mantle
Answer(b) Asthenosphere — the plastic upper-mantle layer over which the plates move.
- practice — not a real PYQ
The boundary between the Earth's crust and the mantle is known as the
- (a)Conrad discontinuity
- (b)Gutenberg discontinuity
- (c)Mohorovicic (Moho) discontinuity
- (d)Lehmann discontinuity
Answer(c) Mohorovicic (Moho) discontinuity — the seismic boundary separating crust from mantle.