* The Earth's Crust: This is the outermost solid layer of the Earth. It is what we walk on, and it is composed mostly of igneous, metamorphic, and sedimentary rocks.
* The Earth's Mantle: Beneath the crust lies the mantle, a thick layer of mostly solid rock. However, the mantle is not entirely solid. It behaves like a very viscous fluid over very long periods of time.
So, the question is a bit confusing because it is not entirely accurate to say there is a *solid* layer of rock beneath the solid crust. There is, however, a layer of mostly solid rock (the mantle) which is beneath the crust.
