The key difference is that the crust is a layer of the Earth, while the lithosphere is a mechanical layer comprising the crust and the uppermost part of the mantle.
Here's a more detailed breakdown:
-
Crust: This is the outermost solid shell of the Earth. There are two types:
- Oceanic Crust: Thinner (typically 5-10 km thick), denser, and primarily composed of basaltic rocks.
- Continental Crust: Thicker (typically 30-70 km thick), less dense, and composed of a variety of rocks, including granite.
-
Lithosphere: This is defined by its mechanical properties. It's a rigid and brittle layer that includes the entire crust and the uppermost part of the mantle. It's this rigid outer layer that is broken into tectonic plates.
To illustrate:
| Feature | Crust | Lithosphere |
|---|---|---|
| Definition | Outermost solid layer of the Earth | Rigid outer layer (crust + uppermost mantle) |
| Composition | Oceanic and Continental Crust | Crust and uppermost mantle |
| Behavior | Component of the lithosphere | Rigid, brittle, broken into tectonic plates |
| Thickness | 5-70 km (depending on type) | ~100 km (can vary) |
In simpler terms, imagine a chocolate bar. The chocolate coating is analogous to the crust. The lithosphere is like the chocolate coating plus a thin layer of the filling directly beneath it that sticks to the coating.
Therefore, while the crust is an essential part of the lithosphere, the lithosphere extends deeper to include part of the upper mantle. You can't have a lithosphere without a crust, but the lithosphere is more than just the crust.
