polar cap vs rink

polar cap

noun
  • A high-latitude region of a celestial body that is covered by ice. 

rink

noun
  • A building housing an ice rink. 

  • A team in a competition. 

  • A man, especially a warrior or hero. 

  • A surface for roller skating. 

  • A ring; a circle. 

  • A sheet of ice prepared for playing certain sports, such as hockey or curling. 

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