Tough economic times may be taking a toll on some of the Southwest's archaeological treasures. Looters are vandalizing remote sites in increasing numbers in search of artifacts they can peddle on the black market.

Their efforts have been aided by new Internet technology and some unwitting amateur enthusiasts.

For centuries the dry climate of the American Southwest has preserved the artifacts and remnants of ancient Indian settlements.

Many sites are well known like Chaco Park or Mesa Verde but thousands of others are not catalogued: hidden in remote canyons or on Indian land, known only to a few archaeologists or desert hikers. For that reason it's hard to know just how much looting is going on, but authorities say there is strong evidence that it's on the rise.

In northern Arizona, tribal law enforcement officer Danny Bulletts pulls over to the side of the highway near the isolated town of Fredonia, to point out where he recently caught someone looting. Officer Bulletts says he is tired of people stealing his ancestors' treasures.

"I was waiting for him and he got behind this mound and he didn't come out," he said. "He saw me and I said 'what are you doin'?' "

It turned out the man was collecting pottery shards from Indian land, in violation of federal laws. And he wasn't the only one to make his way to this ancient Paiute ruin.

Bureau of Indian Affairs archaeologist Gary Cantley points to evidence of recent looting, several deep and roughly dug holes, at the base of an earthen wall.

"See this? This was a room," said Gary Cantley. "See this? This was a wall inside a room. This has been looting. This individual knew what he was doing. An archaeologist would not have excavated like this at all."

The situation is just as bad in western Nevada. Director of the Nevada Rock Art Foundation, Alanah Woody, says she has visited a popular archaeological site every few months for the last 15 years and only recently has she seen a big change.

"The last two years, the vandalism at the site has increased, really radically," said Alanah Woody.

Amateur rock art and Indian artifact lovers may be helping looters without even knowing it. The informal networks that used to share information about archaeological sites by phone and newsletters, now use the Internet.

Ms. Woody says tech-savvy looters with Global Positioning Systems can easily locate rock paintings and archeological sites once these enthusiasts post the precise longitude and latitude coordinates on the Web.

"There was one fellow here in southern Nevada with GPS coordinates," she said. "I actually talked to him on the phone. It never occurred to him that what he did would cause more damage. And it never occurred to him that he was throwing gas on the fire basically."

Looting antiquities will fetch a fairly high price in the black market.

Ken Mabery, president of the Association of National Park Rangers, says the bottom line is, there's money to be made.

"We know that looting is going on and we know in times of an economic downturn that perceived get-rich activities increase," he said.

In fact, a recent search on the Internet auction site Ebay turned up more than 600 Indian artifacts, including arrowheads, beads and pottery. Prices ranged from $5 all the way up to $500.

Mr. Mabery says that funding cuts to the National Park Service have meant major staff cutbacks. So there are fewer rangers to patrol just as many archaeological sites.

"In the last 25 years, visitation to parks has grown 150 percent," said Ken Mabery. "The amount of acreage in national parks has grown by 166 percent. The same time protection staffing has decreased. It's a big precipitous decrease."

Park rangers elsewhere in the country are also reporting an upsurge in looting at archeological sites, and Civil War battlefields as well. So, archaeologists and special agents from the Bureau of Indian Affairs have been touring the country for the past couple of years to train local law enforcement officials how to investigate and fight the crime.