Here's why:
* Glaciers are powerful agents of erosion: Their immense weight and the embedded rock fragments within them carve out valleys and mountainsides.
* Erosion from multiple sides: Glaciers flow down valleys from different directions, carving away the surrounding rock. When glaciers meet, they erode the peaks from multiple sides, creating the sharp, pointed shape of a horn.
* Deposition plays a minor role: Glaciers do deposit material as they melt, but this is primarily responsible for creating moraines (piles of rock and sediment) rather than horns.
In summary: While deposition is a part of the glacial process, the primary force behind horn formation is erosion by glaciers.
