promontory vs rock face

promontory

noun
  • A high point of land extending into a body of water, headland; cliff. 

  • A rounded elevation in the tympanum of the ear. 

  • A projection on the sacrum. 

rock face

noun
  • An exposed, roughly vertical expanse of rock 

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