The Collaborative International Dictionary of English v.0.48:
petroglyph \pet"ro*glyph`\ (p[e^]t"r[-o]*gl[i^]f`), n. A carving or drawing on rock, especially one made by prehistoric humans; called also a petrograph. [PJC]WordNet (r) 3.0 (2006):
petroglyph n 1: a carving or line drawing on rock (especially one made by prehistoric people)