d or scratch
ed on a rock
surface, usually with another rock. Petroglyphs are aften attributed to prehistoric
humans, but in its broadest sense the term also applies to messages like "Srs '99" or "I (heart) Monica" that apparently have much more recent origin.
Petroglyph National Monument, west of Albuquerque, New Mexico, has an amazing concentration of petroglyphs carved over a period of many millenia into basalt. Those as old as 5000 BC are mostly geometric designs; the most recent, from a period between the 1300s and 1600s, depict elaborate human figures, spirit animals, masks, and other images not unlike those appearing in pueblo ceremonial art today.
Petroglyphs are found on all the continents and even on some islands: St. John, the tiniest of the U. S. Virgin Islands, has petroglyphs next to its only fresh-water spring, probably carved by tribespeople from South America that colonized St. John before European explorers arrived. Ancient petroglyphs are not always from indigenous people; the Horse Creek petroglyph in West Virginia appears to be an example of an acient Ogam script used by early Irish and Scottish people, and could have been made as early as 600 or 700 AD.