acclivity vs upthrow

acclivity

noun
  • A slope or inclination of the earth, as the side of a hill, considered as ascending, in opposition to declivity, or descending; an upward slope; ascent. 

upthrow

verb
  • To be thrown up from below, causing a fault. 

  • To throw up (a mass of material) from below, causing a fault. 

noun
  • A fault in which a mass of material has been thrown up from below. 

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