overburden vs submerge

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. 

submerge

verb
  • To engulf or overwhelm. 

  • To sink out of sight. 

  • To put into a liquid; to immerse; to plunge into and keep in. 

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