crag vs crevasse

crag

noun
  • A rocky outcrop; a rugged steep cliff or rock. 

  • A rough, broken fragment of rock. 

  • A partially compacted bed of gravel mixed with shells, of the Pliocene to Pleistocene epochs. 

crevasse

verb
  • To fissure with crevasses. 

  • To form crevasses. 

noun
  • A discontinuity or “gap” between the accounted variables and an observed outcome. 

  • A crack or fissure in a glacier or snowfield; a chasm. 

  • A breach in a canal or river bank. 

  • Any cleft or fissure. 

How often have the words crag and crevasse occurred in a corpus of books? (source: Google Ngram Viewer )