"It's the most beautiful land in Orange County," said Craig, who has owned the tract for some 40 years. "And that's not just my opinion. That land is appreciated by a lot of people, and because of that it's heavily used. That's part of the problem."

For many years, Craig has allowed people to hike, run, walk dogs and otherwise use the trails that crisscross the tract's hilly, wooded terrain. Because it was never marked and abuts public land including Carolina North and Carrboro's Adams Tract, it's likely that many, perhaps most, of those people didn't even realize it was private land they were enjoying.

It is, though, and Craig's open-door policy has come to an end, at least for the time being. He has posted yellow "No Trespassing" signs around the perimeter of the property.

He's done that reluctantly, he said, in response to the construction of large earthen ramps, or moguls, that have been built on portions of his trails by enthusiasts of dirt bicycle jumping. Some of the ramps are many years old, and others look to be of much more recent vintage; at one spot not far from the railroad tracks, a red-handled shovel lay propped against a small ramp under construction last week.

The larger ones are built of dirt packed on top of solid foundations such as railroad ties or large sections of drainage pipe.

The ramps, many of them lined up in close succession so the bikers can jump from one to the next in a series, swoop nearly vertically up from ground level.

"The bikers, and I don't know who they are, have cut logs and dug deep holes to build these things," Craig said. "They act like they own the place, and they have for years. I feel like I've been patient and tolerant, but the situation has gotten extreme. I had to act."

His main concern, he said, is that someone may be injured on the moguls.

"I'm worried about the 13-year-old kid who goes out there and tries to ride one of those things and gets hurt," Craig said. "It would terrible if someone got hurt out there."

A June 1 letter to Craig from forest Jennifer Johnson Roach of the state Department of Environment and Natural Resources said, "the 20-40 bike jumps that I saw concern me simply from a liability standpoint. There are a lot of people spending time on your property doing whatever they please, but if they get hurt you could be liable."

Dave Otto, the head of the Friends of Bolin Creek, said Craig had made clear long ago that the dirt jumper and their moguls were not welcome on what Otto called a "natural treasure."

"Craig voiced strong objections to this use of his property and threatened to post 'no trespassing' signs if the dirt jumpers persisted in building and using the moguls," Otto said. "The bikers ignored the warning and Craig followed through with his threat, denying access to all."

Steve Rogers, a local mountain biker, said he and many other cyclists used to ride in the Craig tract, but most of them stopped several years ago when they learned that Craig didn't want bikes on the trails.

"I think most of the mainstream mountain biking community got the word that he didn't want wheeled vehicles out there, and stopped," Rogers said. "The biggest issue is the dirt jumpers who kept on building the moguls and riding there even after it was clear the Mr. Craig didn't want that activity going on there.

"It's a real shame, because that is a beautiful piece of property."

The DENR letter also points out that a number of the trails on Craig's property either cross Bolin Creek or go straight up and down the hills, both of which contribute to erosion and sedimentation in the creek. Reconfiguring the trails to prevent excessive erosion would be "a difficult project that will require a lot of time and money," the DENR letter said. "The forestry folks have told me I have to get control of my property," Craig said. "I've tried to be a good guy all these years, but it's been taken advantage of, and I had to do something in order to get control of the situation and be a good steward of the land."

Craig said he has talked with Carrboro officials over the years about selling the tract to the town to use and manage as public land, but those talks never produced an agreement. And with the economy in poor shape, few local governments are looking for big purchases to make just now.

So for the time being, the Craig tract is off limits. Otto said plans are under way to remove the moguls, improve the tails and restore access to the tract. Rogers is among those working on that effort.

"Those trails grew up organically over many, many years," Rogers said. "They were not built with any notion of long-term sustainability or consequences to the creek bed.

"So one problem is that limiting access doesn't really solve those sedimentation issues.

"The bottom line is that the land is his, and he can do what he wants with it. But the overall goal, the thing a lot of people would love to see, is the purchase of that property and making sure it's preserved for the future."