engulf vs overburden

engulf

verb
  • To overwhelm. 

  • To surround; to cover; to submerge. 

  • To cast into a gulf. 

overburden

verb
  • To overload or overtax. 

noun
  • A sterile stratum that lies above the stratum being investigated 

  • The rock and subsoil that lies above a mineral deposit such as a coal seam. 

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