An outcrop is a place where bedrock (the solid rock layer beneath soil and loose material) pokes up through the ground and becomes visible at the surface. You've probably seen outcrops if you've ever hiked in mountains or explored rocky areas: those gray or brown rock formations jutting out from hillsides, or flat expanses of stone you can walk across.

Geologists love outcrops because they reveal Earth's history like pages in a book. By studying the layers, colors, and types of rock in an outcrop, scientists can learn about ancient volcanoes, prehistoric seas, or forces that folded mountains millions of years ago. A single outcrop might show wavy patterns from ocean waves that lapped against a beach when dinosaurs roamed, or crystals that formed deep underground and were later pushed to the surface.

While most bedrock stays hidden under dirt and vegetation, outcrops give us rare windows into the planet's deep structure. Rock climbers often practice on outcrops, and sometimes homeowners discover outcrops in their yards when digging, finding solid stone where they expected only soil.