The government was so excited by rock carvings found in a national forest that it started building an interpretive center to explain to visitors how ancient people carved them as messages to spirits.

But when artist Jeff Kerker saw a magazine story about the petroglyphs, he sent a message of his own to the U.S. Forest Service: The carvings were his handiwork and were only 15 years old."I wasn't trying to fool anyone," said Kerker, of Bandon. "I was interested in how long it might take to make them. All it took was one afternoon."

Kerker said he had photos of the carvings in the Siskiyou National Forest to prove he made them.

The Forest Service was waiting to see Kerker's evidence before deciding whether his story was true. But enough of a question was raised that work was suspended on the interpretive center being built at Daphne Grove outside Powers, spokeswoman Patty Burel said Tuesday.

"There is the off chance we never will be able to tell, since there is no exact science for dating petroglyph art like this," she said. "Right now everything is on hold."

The carvings were discovered in 1987 on three boulders along the South Fork of the Coquille River, Burel said. One represented a fish, but the others weren't clear.

The carvings were taken to a Forest Service office for preservation, and replicas were carved for the interpretive center.

A variety of archaeologists inside and outside the Forest Service examined the carvings and decided they were genuine, Burel said.

One reason was that the carvings had been eroded, and another was that they were below the river's high water mark.

"That was important, because the petroglyphs were considered to have spirits," said Janet Joyer, archaeologist for the Siskiyou National Forest. "When the water rose, then the petroglyphs would be under water. They were thought to transmit the people's prayers down to the salmon people.

"The salmon people lived underwater in human form. When they were requested by human beings, they took on fish forms and sacrificed themselves."

Kerker said he had figured the water would erode the carvings from the soft stone and never thought anyone would discover them.

Joyer said the development carries a good lesson.

"This will be important for archaeologists, a reminder that we must be conservative with things like this that are not dateable," she said.