JOSHUA TREE NATIONAL PARK, Calif. (AP) — Acts of graffiti have become so pervasive at Joshua Tree National Park’s most popular hiking spots that officials have had to close them to the public, and they blame the big bump in vandalism on social media.

Rangers said they’ve found graffiti spray painted on 17 sites, including the famous rock formations and historic Native American sites, at the Southern California park’s Rattlesnake Canyon. They put historic Barker Dam off limits after vandals carved their names into the cement of the Old West landmark.