Glacial plucking is the process by which a glacier removes large chunks of bedrock as it moves. This occurs when meltwater infiltrates bedrock fractures, freezes, and then as the glacier moves, it pulls the loosened rock fragments away. Plucking plays a key role in glacial erosion and the formation of jagged mountain landscapes.
Reference: Benn, D. I., & Evans, D. J. A. (2010). Glaciers and Glaciation. Routledge.