coulee vs couloir

coulee

noun
  • A deep gulch or ravine, frequently dry in summer. 

  • A stream. 

  • A lava flow. 

  • A reach of water in a bayou that is like a slough but deeper. 

couloir

noun
  • A steep gorge along a mountainside. 

  • A corridor or passage. 

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