More than 700 years ago, the ancient inhabitants of Canyonlands painted mystical white faces on a red sandstone wall in an alcove in Horse Canyon. Some faces looked sinister, while others looked almost angelical.

Next to the "Nine Faces" panel, someone else has scratched a skull surrounded by a large satanic pentagram. The pentagram is no more than a year old - having been left by one of the thousands who visit Canyonlands National Park every year.More than ever before, vandals are carving their way through Canyonlands National Park, says Park Service archaeologist Chas Cartwright. And it's a problem that now jeopardizes one of Utah's most unique resources.

"Until recently we haven't had the graffiti problems other areas have had," Cartwright said. "Most other rock art sites in the Southwest have received some form of vandalism from bullet holes to graffiti. But here, it's been preserved in a relatively pristine condition."

But that is changing as more and more people discover Canyonlands. Park rangers have responded to at least six cases of vandalism of ancient rock art within the last year, and experts predict the incidents will continue to rise.

"In several more decades, the quality experience won't be there any more. All rock art sites will have some sort of damage to them," Cartwright said. "Our visitation is growing at 10 percent a year, and with a park this big it's hard to control what people are doing."

Cartwright says the National Park Service must do a better job of educating its visitors about the delicate, irreplaceable nature of ancient rock art. Many of the problems are being caused by large groups who don't realize the extent of the damage they do.

They want to touch pictographs, not realizing the oils from their hands destroy the ancient paints. They don't realize by scratching their initials into the sandstone it invites others to do the same.

"People see rock art and they want to replicate it," said Cartwright. "They want to leave their mark so they carve their initials into the rock. One problem we're seeing is people taking rocks and rubbing the existing rock art."

When they do, archaeologists like Cartwright respond with nylon brushes, water color paints and an assortment of conservation strategies to try to restore the rock art panels to their original condition. They are rarely restored 100 percent.

"But we have to get it off," he said. "Once it's on, it invites more. It's like a neon sign inviting everyone else to keep putting (graffiti) on."

Vandalism of ancient rock art has been occurring almost since the Anasazi and Fremont Indians scrawled their stories into the southern Utah sandstone. But national parks and monuments have traditionally avoided vandalism, due in large part to the large numbers of rangers assigned to protect those resources.

"It's hard for some people to understand that the ancients did it but you can't," said Cartwright. "They don't understand this isn't just any rich archaeological area. It's one of the richest in the world and it has to be left alone for others to enjoy."

Canyonlands is a unique national park, says Cartwright, because the ancient ruins, rock art and artifacts remain in much the same condition they have been for hundreds of years.

It's also unique because of the distinct styles and quantities of rock art - many painted in golds, blues, reds, whites, greens and oranges - found more plentiful here than anywhere else.

"National parks are supposed to be the best of the best," Cartwright said. "But we have a dilemma. We are saying to the public, `come one come all' but we also have a mandate to preserve and protect."

The question is whether the Park Service can do both in the face of growing numbers of visitors.

"We have to spend more time educating the public and making them an ally of protecting these resources," he said. "Looting is not a significant problem in Canyonlands. But we could lose our resources nonetheless."