The type of earth scientist who studies the lithosphere is a geologist.

Here's why:

* Lithosphere: This is the rigid outer layer of the Earth, comprised of the crust and the uppermost part of the mantle.

* Geologists: These scientists study the Earth's solid, non-living components, including rocks, minerals, and the processes that shape the Earth's surface.

While other earth scientists might have some involvement with the lithosphere, geologists are the primary experts in its composition, structure, and dynamics.