serac vs tor

serac

noun
  • A sharp tower of ice formed by intersecting crevasses of a glacier. 

  • Often sérac: a hard, cone-shaped, pale green, strongly flavoured cheese from Switzerland made from skimmed cowmilk and blue fenugreek (Trigonella caerulea); Schabziger, Sapsago. It is usually eaten grated, mixed with butter, or in a fondue. 

tor

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

  • A hill with such rock formation. 

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