#gravel__crushed_rock__crushedrock  rock fragments and pebbles
  supertype:  #rock__stone  material consisting of the aggregate of minerals like those making up the Earth's crust
  subtype:  #bank_gravel__pit-run_gravel__pitrungravel__pit_run__pitrun  gravel as found in natural deposits
  subtype:  #shingle.gravel  coarse beach gravel of small water-worn stones and pebbles (or a stretch of shore covered with such gravel)

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