delve vs rootle

delve

verb
  • To dig into the ground, especially with a shovel. 

  • To search thoroughly and carefully for information, research, dig into, penetrate, fathom, trace out 

  • To dig; to excavate. 

rootle

verb
  • to dig into the ground, with the snout. 

  • to search for something from a drawer, closet, etc.; to dig out. 

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