The crust is Earth's outermost, solid layer, composed of rocks and minerals.
It represents only about 1% of Earth's total volume and extends to a depth of approximately 30-40 kilometers. The crust is also the coolest layer compared to the Earth's mantle and core. It exists in two primary forms:
- Oceanic Crust: Thinner (typically 5-10 km thick), denser, and primarily composed of basaltic rocks.
- Continental Crust: Thicker (typically 30-50 km thick, and up to 70 km under mountains), less dense, and primarily composed of granitic rocks.
The crust is fragmented into tectonic plates that float on the semi-molten mantle below, causing earthquakes, volcanic activity, and the formation of mountains.
