| What: "Pictographs on the central Plateau tend not to cluster, as do petroglyphs; however, along a short stretch of the Okanogan River just south of Tonasket six pictograph sites have been recorded. These small, well-executed sites each contain between five and twenty paintings. This clustering is similar to that observed in interior British Columbia and in western Montana. Each of these clusters, along with others seen elsewhere on the Plateau, documents that, once begun, many rock art sites became important places to which the Indians would return through many generations to add more paintings or carvings."
From: Indian Rock Art of the Columbia Plateau, by James D. Keyser