debark vs descend upon

debark

verb
  • To devocalize (a dog). 

  • To disembark. 

  • To unload goods from an aircraft or ship. 

  • To remove the bark from a tree, especially one that has been felled. 

descend upon

verb
  • to visit in large numbers 

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