Here's a breakdown:

* Continental Crust: Typically ranges from 30 to 70 kilometers (19 to 43 miles) thick. It's composed of less dense rocks like granite and andesite.

* Oceanic Crust: Ranges from 5 to 10 kilometers (3 to 6 miles) thick. It's primarily made up of denser basalt and gabbro.

This difference in thickness is due to the different origins and composition of the two types of crust:

* Continental crust: Formed over billions of years through various processes, including volcanic eruptions, accretion of sediments, and collisions of tectonic plates.

* Oceanic crust: Formed at mid-ocean ridges where magma rises and solidifies.

The thicker nature of continental crust also contributes to its higher elevation, resulting in continents being above sea level while oceanic crust forms the ocean floor.