The crust is the thinnest layer. Humans have gone down miles but have not got to the mantle. The earth’s crust is divided into two areas: the Continental Crust and the Oceanic Crust. The crust under the ocean is thinner than the crust on the continents. There are Felsic rock, granite, and Gneiss rocks in the crust on land. Under the ocean, there is mafic rock, basalt, and gabbro rocks. Ocean crust is denser.

We know the mantle is mostly solid because of seismic evidence. Upper mantle possibly consists of dense igneous rock. The mantle has some magma chambers.

We know there is a core because seismic waves do not appear on the other side. We think the core is made of iron or nickel. The core must be dense.

There are three parts of the earth: the crust, mantle, and core.