“I enjoy being out there, being quiet and appreciating the people who lived there 1,000 years ago  imagining what Chimney Rock meant to them,” said Mr. Gwin, who leads tours as an unpaid volunteer for the federal Forest Service at the Chimney Rock Archaeological Area, about an hour east of here.

But population growth has also brought people who are not so reverent. Instances of vandalism and illegal raids for relics  as more footprints are found leading out into once-silent Indian mounds  have risen sharply in the last few years, though few offenders are caught.

Federal land managers, tribal leaders and archaeologists call it piling on. Energy companies build roads for access to their drill pads. But then expanding populations, many of them riding off-road vehicles, use those roads for exploration or exploitation. What was once remote becomes less so, and harder than ever to defend for future generations.

“Multiple use worked for a while, but now the uses are in the same place,” said Terry Morgart, a legal researcher for the Hopi tribe in Arizona. “You can’t have recreation, cultural resources, energy development and cell towers all on the same spot. I think the agencies are aware of these conflicts, but because they’re stuck with these archaic laws, they’re between a rock and a hard place.”

Indian leaders, who link modern tribal populations in the Southwest to the ancestral Anasazi, have mounted a campaign to stop the local exploration for carbon dioxide, which would be used to help rejuvenate old oil fields that are now stirring to life in Texas and elsewhere as oil prices soar.

“Fencing dozens of sites for the facilitation of energy development is not what we had in mind when we supported the designation of the monument,” said Leigh J. Kuwanwisiwma, the director of the Hopi Cultural Preservation Office, in a letter in April to federal agencies.