A cirque glacier is formed as the edges of a larger glacier erode, leaving a mass of ice and snow nestled against a mountainside. The glacier's weight against the mountainside further erodes the rock, forming the hollow cirque for which it is named.
Though cirque glaciers are categorized as “confined” because they are situated in alpine nooks, they still change over time. Drifting snow often becomes part of the cirque glacier, causing it to constantly shift and change shape. When two or more cirque glaciers meet, they can simultaneously erode a mountain on all sides, creating a sharp peek called a horn. The Matterhorn in Switzerland is one such famous formation.
Cirque glaciers are found on high mountainsides. They are the smallest of alpine glaciers, and can be found in many parts of the world, from Yosemite National Park to the Swiss Alps.
