agglomeration vs treasure-trove

agglomeration

noun
  • State of being collected in a mass; a mass; cluster. 

  • An extended city area comprising the built-up area of a central city and any suburbs linked by continuous urban area. 

  • The act or process of collecting in a mass; a heaping together. 

  • a mass of large volcanic fragments bonded under heat. 

treasure-trove

How often have the words agglomeration and treasure-trove occurred in a corpus of books? (source: Google Ngram Viewer )