san rock art at twyfelfontein, namibia

africa african age ancient animals archaeological archaeology archeological archeology art artwork bushman bushmen carved carving damaraland elephant engraved engraving engravings gazelle geology giraffe heritage khoikhoi kunene lion namibia namibian oryx petroglyph petroglyphs rhino rhinoceros rock san sandstone scratched site stone twyfelfontein unesco wildlife world zebra