clunch vs flagstone

clunch

noun
  • A traditional building material mostly made of chalk or clay. 

verb
  • To grasp firmly; clench. 

flagstone

noun
  • A flat, rectangular piece of rock or stone used for paving or roofing. 

  • One of several types of rock easily split and suitable for making flagstones. 

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