pebble vs scree

pebble

noun
  • A small stone, especially one rounded by the action of water. 

  • A form of slow-burning gunpowder in large cubical grains. 

  • A particle from 4 to 64 mm in diameter, following the Wentworth scale. 

  • Transparent and colourless rock crystal. 

  • A small droplet of water intentionally sprayed on the ice that cause irregularities on the surface. 

verb
  • To pave with pebbles. 

  • To place a pebble at (a vertex of a graph) according to certain rules; see pebble game. 

  • To deposit water droplets on the ice. 

  • To give (leather) a rough appearance with small rounded prominences. 

scree

noun
  • Loose stony debris on a slope. 

  • Similar debris made up of broken building material such as bricks, concrete, etc. 

  • A coarse sieve. 

  • A harsh, high-pitched sound or cry (as of a hawk). 

  • A slope made up of loose stony debris at the base of a cliff, mountain, etc. 

verb
  • To flatten or level concrete while still wet, and remove protruding gravel and stones from the surface. 

  • To traverse scree downhill. 

  • To make a high-pitched cry like that of a hawk. 

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