Painting and engraving on rock or cave surfaces, done as decoration, depiction of narratives, or for religious purposes. There are petroglyphs (carvings on rock face), engravings (incisions), and pictographs (paintings on rock surfaces). A great deal of rock art occurs throughout African continent. In contrast to painted caves of Europe, the African art takes the form either of paintings in rock shelters (not in caves) or engraving on open rock outcrops or boulders.