 The site where these petroglyphs were found was inundated by the rising waters behind Wanapum Dam in the 1960s.About 60 of the more than 300 carvings were cut from the basalt cliff face and saved.The nearby Ginkgo Petrified Forest site is one of the most unusual fossil forests in the world, and was designated a National Natural Landmark by the National Park Service in 1965.