carr vs muskeg

carr

noun
  • A marsh or fen on which low trees or bushes grow; a marshy woodland. 

  • rock 

  • A bog or marsh; marshy ground, swampland. 

muskeg

noun
  • A terrain composed of peat bog with tussocky meadow and woody vegetation including spruce. 

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