Reference Work Entry

Geomorphology

Part of the series Encyclopedia of Earth Science pp 457-458

Glacial plucking (quarrying)

  • Rhodes W. Fairbridge

In glacial erosion, in addition to abrasion (q.v.) which leaves striations, gouge marks, etc., a peculiar pulling away process is called glacial plucking or quarrying, because it involves the dislodging and removal of large fragments and boulders. It is a characteristic process of lee sides of rochesmoutonnées (q.v.), of the downstream side of “glacial stairs,” and of the inner and deeper parts of the bergschrundcrevasses of cirque glaciers. It is probable that very often meltwater running into the joint planes causes frost splitting (Carol, 1947), but also the mechanical process of ice freezing onto projecting rocks has the ultimate effect, as the glacier moves on, of pulling the rocks away from their foundations. The pressure changes as the glacier moves over may also lead to stress release effects (Lewis, 1954). Comparisons of the amount of erosion on the

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