overburden vs sand trap

overburden

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

  • A sterile stratum that lies above the stratum being investigated 

verb
  • To overload or overtax. 

sand trap

noun
  • A basin that prevents the passage of sand etc into a drainage system. 

  • A sand-filled hollow, on a golf course, used as a hazard; a bunker. 

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