How does glacial erosion create sharp mountain peaks called horns?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Snow-capped, rugged Atlas Mountains encircle a green valley with scattered trees, terraced fields, and a few small buildings in Morocco. — valley The rugged Atlas Mountains surround a valley in Morocco.

Horns are sharp, pyramid-shaped mountain peaks formed through the process of glacial erosion. They develop when three or more cirques are arranged in a radial pattern around a single mountain summit.2

As these cirques undergo headward erosion, their steep, amphitheatre-shaped headwalls retreat toward the center of the mountain. This process narrows the bedrock divides between the cirques into jagged, knife-edge ridges known as arêtes. When these arêtes meet at a central point, they leave behind a solitary, pointed peak flanked by nearly vertical cliffs. A classic example of this landform is the Matterhorn in the Swiss Alps.12