While it's not a single, uniform solid, it's made up of:
* Earth's crust: The outermost layer, primarily composed of igneous, sedimentary, and metamorphic rocks.
* Uppermost part of the mantle: This is the layer beneath the crust, which is also mostly solid but behaves more like a very viscous fluid over long periods.
It's important to note that while the lithosphere is primarily solid, there are areas within it that can behave like a fluid under extreme pressure and heat, such as during plate tectonics movements.
