Petroglyphs are images created by removing part of a rock surface by incising, picking, carving, or abrading, as a form of rock art. Scholars often use terms such as carving or engraving. Petroglyphs are found world-wide, and are often associated with prehistoric peoples. Some petroglyphs are dated to approximately the Neolithic and late Upper Paleolithic boundary, about 10, 000 to 12, 000 years ago. Sites in Australia have petroglyphs that are estimated to be as much as 27, 000 years old, and even 40, 000 years old. Around 7, 000 to 9, 000 years ago, other precursors of writing systems, such as pictographs and ideograms, began to appear. Some cultures were still using petroglyphs in the 20th century. Petroglyphs have been found in all parts of the globe except Antarctica with highest concentrations in parts of Africa, Scandinavia, Siberia, southwestern North America and Australia. Image appeared in The Story of the Alphabet by Edward Clodd, 1938. |