The granite that makes up Pikes Peak was once molten rock that slowly cooled and hardened miles beneath the earth’s surface, allowing crystals to grow. Over the last 500 million years, collisions among tectonic plates pushed this cooled granite upward. Around 65 million years ago, a tectonic plate beneath the Pacific Ocean was driving into the North American continent, creating tremendous mountain-building pressure below what is now Colorado and forming Pikes Peak. From two million to 10,000 years ago, a series of Ice Age climates covered the land, and alpine glaciers on Pikes Peak gouged bowl-like hollows and U-shaped valleys. Since then, erosion has continued to sculpt the rugged mountain. Pikes Peak Granite is more than a billion years old, and its large crystals of quartz, feldspar, and mica reveal its origin.