Earth Science and Environmental Pollution Practice Exam 2026 - Free Environmental Science Practice Questions and Study Guide

You’re standing on the crust, the outermost solid layer of Earth. This thin shell supports all surface features you see—continents, oceans, soils, and rocks. There are two main types of crust: continental crust, which is thicker and lighter, made largely of granitic rocks, and oceanic crust, which is thinner and denser, composed mostly of basalt. Beneath the crust lies the mantle, extending far downward, then the outer core (a flowing liquid made of iron and nickel) and the inner core (a solid ball of iron-nickel at the center). The surface you experience every day is the crust, so that is the correct layer.