Britannica
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How do several cirques erode a mountain into a horn?
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glacial landform
Eskers,
or narrow
ridges of
gravel and sand left by a retreating glacier,
wind through western
Nunavut, Canada, near the Thelon River.
A horn is formed when a mountain is subjected to radial glacial erosion from multiple sides. When three or more cirques develop around the flanks of a mountain, they undergo headward erosion, cutting into the mountain's mass.1
As these cirques expand, they are separated by arĂȘtesâjagged, knife-edge ridges created by the glacial erosion of the bedrock between parallel valleys or opposing cirques. The continued retreat of the cirque headwalls eventually consumes the surrounding rock, leaving behind a sharp, pyramid-shaped peak flanked by nearly vertical cliffs. A classic example of this process is the Matterhorn in the Swiss Alps.1