What is a horn and how is it formed? Give an example
A horn is formed when glaciers erode three or more arêtes, usually forming a sharp-edged peak. Cirques are concave, circular basins carved by the base of a glacier as it erodes the landscape.It is also known as a pyramidal peak. An arete is the edge that forms in the land from cirque erosion. Horn forms when more than two aretes meet. The Matterhorn in Switzerland is a horn carved away by glacial erosion.