burian vs molehill

burian

noun
  • A barrow; mound; tumulus 

  • A camp; hill-fort. 

  • A tomb; sepulchre. 

molehill

noun
  • A small mound of earth created by a mole's burrowing underneath the surface of the ground. 

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