Officials at Utah's Arches National Park are investigating large graffiti so deeply carved into one of the park's famous red rock arches that it might be impossible to erase.

Park Superintendent Kate Cannon says the carvings discovered last week span 5 or 6 feet on Frame Arch and include names and messages.

Cannon said Thursday that the vandalism is so deeply etched that it might have taken at least an hour for someone to carve. She's unsure if park officials will be able to repair the arch.

The arch is off a popular hiking trail in the park where visitors can look through it and view the park's iconic, stand-alone Delicate Arch.

Cannon says the graffiti is part of a major increase in vandalism at Arches and other national parks. Officials hope public outrage and vigilance can combat the problem.