Vandals tape themselves using jacks to roll huge boulders into Wyoming canyon.
A video posted on YouTube has drawn the attention of federal investigators.
In the video several people are watching others use car jacks to dislodge large boulders and roll the rocks into a canyon near Wyoming's Pathfinder Dam.
Within the last few days calls reporting the video have poured in to the Natrona County Sheriff's Office.
"It is illegal, I will tell you that much and we discourage anyone else from doing it," says Lt. Mark Sellers.
Because Pathfinder is federal land, the case has been turned over to the Bureau of Reclamation.
The video has been removed from YouTube by the user.