heugh vs ravine

heugh

noun
  • A steep crag or cliff, especially one with overhanging sides 

  • A glen with steep, overhanging sides 

  • A steep excavation, especially a coal pit 

ravine

noun
  • A deep narrow valley or gorge in the earth's surface worn by running water. 

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