obelisk vs rockpile

obelisk

noun
  • A tall, square, tapered, stone monolith topped with a pyramidal point, frequently used as a monument. 

  • A dagger symbol (†), which is used in printed matter as a reference mark to refer the reader to a footnote, marginal note, etc.; beside a person's name to indicate that the person is deceased; or beside a date to indicate that it is a person's death date. 

  • A symbol resembling a horizontal line (–), sometimes together with one or two dots (for example, ⨪ or ÷), which was used in ancient manuscripts and texts to mark a word or passage as doubtful or spurious, or redundant. 

verb
  • To adopt the obelisk posture; to point the tip of the abdomen towards the sun. 

rockpile

noun
  • A pile of rocks. 

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