"Petroglyphs in the Columbia River Gorge" by U.S. Army Corps of Engineers, photographer unknown - U.S. Army Corps of Engineers Digital Visual LibraryImage pageImage description pageDigital Visual Library home page. Licensed under Public domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Petroglyphs_in_the_Columbia_River_Gorge.jpg#mediaviewer/File:Petroglyphs_in_the_Columbia_River_Gorge.jpg Apskatīt