fringing reef vs ledge

fringing reef

noun
  • A completely shallow coral reef adjacent to a coast. 

ledge

noun
  • A shelf, ridge, or reef, of rocks. 

  • A provincial or territorial legislative assembly. 

  • A cornice. 

  • A (door or window) lintel. 

  • A piece of timber to support the deck, placed athwartship between beams. 

  • A lode; a limited mass of rock bearing valuable mineral. 

  • A provincial or territorial legislature building. 

  • A layer or stratum. 

  • A shelf on which articles may be laid; also, that which resembles such a shelf in form or use, as a projecting ridge or part, or a molding or edge in joinery. 

verb
  • To cause to have, or to develop, a ledge (during mining, canal construction, building, etc). 

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