descent vs irruption

descent

noun
  • A falling upon or invasion. 

  • A particular extension of the idea of gluing. 

  • A sloping passage or incline. 

  • A drop to a lower status or condition; decline. 

  • Lineage or hereditary derivation. 

  • An instance of descending; act of coming down. 

  • A way down. 

irruption

noun
  • The action of irrupting or breaking into; a violent entry or invasion; an inbreaking; an intrusion. 

  • An abrupt increase in the size of a movement or organization. 

  • An abrupt increase of an animal population. 

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