macadam vs rubble

macadam

noun
  • The surface of a road consisting of layers of crushed stone (usually tar-coated for modern traffic). 

verb
  • To cover or surface with macadam. 

rubble

noun
  • The broken remains of an object, usually rock or masonry. 

  • The whole of the bran of wheat before it is sorted into pollard, bran, etc.. 

  • A mass or stratum of fragments of rock lying under the alluvium and derived from the neighbouring rock. 

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