couloir vs crevasse

couloir

noun
  • A corridor or passage. 

  • A steep gorge along a mountainside. 

crevasse

noun
  • A breach in a canal or river bank. 

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

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

  • Any cleft or fissure. 

verb
  • To fissure with crevasses. 

  • To form crevasses. 

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