cross the river vs keel over

cross the river

verb
  • Synonym of pass the river (to die) 

keel over

verb
  • To die. 

  • To collapse in a faint; to black out, to swoon. 

  • Of a vessel: to roll so far on its side that it cannot recover; to capsize or turn turtle. 

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