excavate vs go to the bottom

excavate

verb
  • To uncover (something) by digging. 

  • To make a hole in (something); to hollow. 

  • To remove part of (something) by scooping or digging it out. 

noun
  • Any member of a major grouping of unicellular eukaryotes, of the clade Excavata. 

go to the bottom

How often have the words excavate and go to the bottom occurred in a corpus of books? (source: Google Ngram Viewer )