argillic vs earthy

argillic

adj
  • Of or pertaining to clay or clay minerals. 

noun
  • A soil of this kind. 

earthy

adj
  • Resembling dirt or soil (i.e. earth). 

  • Coarse and unrefined, crude. 

  • Like or resembling the earth or of the earth. 

  • Covered with earth (mud, dirt). 

  • Down-to-earth, not artificial, natural. 

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