ford vs vault over

ford

noun
  • A location where a stream is shallow and the bottom has good footing, making it possible to cross from one side to the other with no bridge, by walking, riding, or driving through the water; a crossing. 

  • A stream; a current. 

verb
  • To cross a stream using a ford. 

vault over

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