late 14c., from Old French escare "scab" (Modern French escarre), from Late Latin eschara, from Greek eskhara "scab formed after a burn," literally "hearth, fireplace," of unknown origin. English sense probably influenced by Middle English skar (late 14c.) "crack, cut, incision," from Old Norse skarð, related to score (n.). Figurative sense attested from 1580s.
"bare and broken rocky face of a cliff or mountain," 1670s, earlier "rock, crag" (14c.), from Old Norse sker "isolated rock or low reef in the sea," from Proto-Germanic *sker- "to cut" (from PIE root *sker- (1) "to cut") on the notion of "something cut off."