As a geomorphic weathering process, plucking is a type of mass wasting which occurs as a glacier flows over a rocky outcrop it covers. "Plucking" refers to the removal of chunks of rock from the outcrop's lee side by brute mechanical force. Unlike freeze/thaw erosion, the flowing ice simply tears blocks of rock from the rock face, carrying them away to be deposited as glacial boulders somewhere else.

The diagram below shows a glacier plucking chunks from a buried outcrop, which may one day be exposed as a roche moutonnée (aka sheepback):


       -> -> flow direction -> ->
 ---------                                      __________        -----------
                 ----------           ____.----'          |          /'-.
              ________        ___.---'                    |__       /   /
                        __.--'                            |  |     /   /   _________
          --------  _.-'                                  |  |_    '-./
                _.-'                                         | |
            _.-'                                               |_
        _.-'                                                   | |  -------------
    _.-'                                                       | |
_.-'                                                           | |
                                                                 |
                                                                 |

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