An orogeny is a period of mountain building caused by movements of Earth’s crust. The Appalachian Orogeny happened when the North American, European, and African plates collided millions of years ago, forming huge mountains that once looked like today’s Himalayas. Over time, erosion wore them down into the smaller Appalachian Mountains we see today.

This process happened in three main stages—the Taconic, Acadian, and Alleghenian orogenies—each leaving behind layers of rock that tell the story of West Virginia’s ancient past. Many of these rocks, like the Tuscarora Sandstone at Seneca Rocks (Pendleton County) and Caudy's Castle (pictured, in Hampshire County)), formed during these powerful geologic events.

After the ancient sea basin disappeared, weathering and erosion shaped the land for millions of years. The mountains were worn down into a flat plain, then lifted up again about 30 to 50 million years ago. Continued erosion since then has created the landscape we see in West Virginia today.