its solid and cool because the outside cools faster than the inside
No. It is a solid.
The earth's crust is generally solid.
The crust.
The lithosphere crust
It is said that the crust and the inner core are to be solid.
Another word for the Earth's crust is lithosphere. It is the solid outermost layer of the Earth.
It is the Mantle.
The layer of solid unbroken rocks in the Earth's crust is called the lithosphere.
The solid rock forms the Earth's crust on which we live.
It is rock.
The Inner Core is a liquid. Outer core: solid mantel: inbetween crust: solid
The crust, more specifically the lithosphere.