burian vs tor

burian

noun
  • A camp; hill-fort. 

  • A tomb; sepulchre. 

  • A barrow; mound; tumulus 

tor

noun
  • A hill with such rock formation. 

  • A craggy outcrop of rock on the summit of a hill, created by the erosion and weathering of rock. 

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