liminal vs primeval

liminal

adj
  • Of or pertaining to a beginning or first stage of a process. 

  • Of or pertaining to an entrance or threshold. 

primeval

adj
  • Belonging to the first ages. 

  • Primitive. 

  • Primary; original. 

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