ditch vs plunge pool

ditch

noun
  • A trench; a long, shallow indentation, as for irrigation or drainage. 

  • A raised bank of earth and the hedgerow on top. 

verb
  • To dig ditches around. 

  • To dig ditches. 

  • To throw into a ditch. 

  • To discard or abandon. 

  • To deliberately not attend classes; to play hookey. 

  • To deliberately crash-land an airplane on water. 

plunge pool

noun
  • A pool that is small in diameter, but deep, usually resulting from erosion by a natural force such as a waterfall or rapids. 

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