The crust, the outermost layer or surface layer, is the thinnest layer of Earth. In addition to being thin, the crust layer has the most variance when it comes to thickness. This diverse layer mostly ranges from 5km to 30km in thickness but can reach depths of 70km.
Earth's crust is made up of many substances, including water, granite, basalt, silicon, aluminum, sodium and potassium. The crust is extremely thin in the oceans and gets thicker underneath the continents. The Earth's crust reaches its thickest density in mountainous regions. Interestingly, this layer only accounts for about 1 percent of the total volume of the planet.