- small, waterworn stones or pebbles such as lie in loose sheets or beds on a beach.
"loose stones on seashore," 1513, probably related to Norw. singl "small stones," or N.Fris. singel "gravel," both said to be echoic of the sound of water running over pebbles. (http://dictionary.reference.com/browse/shingle)
"But in the field, where the federals were still like shingles in the sea, the revolution did not subside."
- John Womack, Zapata and the Mexican Revolution