Meaning of ripple mark

rip'ple mark"

Pronunciation: [key]
— Geol. Geol.
  1. one of the wavy lines or ridges produced, esp. on sand, by the action of waves, wind, or the like.
  2. one of such forms preserved in sandstone or siltstone.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.