Scott Travis stepped delicately around the ruins of Cliff Palace, his eyes deftly scanning the sandstone bricks, the carefully carved windows and the well-worn wooden beams of one of Mesa Verde National Parks most extensive cliff dwellings. Below him, hundreds of voices in a harmony of different languages filtered up through the air as tourist groups streamed through the ruins.
As he walked, Travis, the parks chief archaeologist, pointed out cracks in the stone walls and misshapen kivas, the traditional buildings used by the ruins architects for gatherings and ceremonies.
But the stability and preservation of Cliff Palace, one of the parks most iconic structures, is one of increasing concern for park officials. Of all the parks ruins, the palace is unique in the scale of the problems going on there, Travis said.
Ultimately, weve got a lot of localized things and a lot of broadscale (issues), as well, that were starting to see the effects of in a fairly dramatic way, he said.
The structures of Mesa Verde, including 600 cliff dwellings, were built by the ancestral Pueblo people who lived there from A.D. 550 to A.D. 1300. Cliff Palace is an intricate mix of towers, multistory stone rooms and kivas built into a soaring alcove in the canyon wall.
Officials estimate that 160,000 people visit this interpretive centerpiece of the park every year.
But many of the structures within the palace are exhibiting signs of destabilization and deformation that park officials call alarming.
A fault line running parallel to the back of Cliff Palace is threatening the southern half of the ruin and Kiva F, one of the key stops on guided tours. The structures are slowly sliding toward the lip of the alcove because the ground beneath them is loose material. Park officials have been forced to close Kiva F to tours to avoid further damage.
The walls of other kivas also are sagging or disfigured and large cracks run down the walls of the buildings. Precipitation at the opening of the alcove and water seepage near the back have speeded the degradation of many structures.
The slow destruction is the result of many factors, including water seepage and precipitation, natural geological aging and impacts from rodents, birds and insects, Travis said. Visitation alone also presents a huge challenge, he said. And while more preservation work has been done to Cliff Palace than any other place in the park, such work added outdated modifications and materials that preservationists now have to work with.
Its a complex equation, putting it all together, Travis said.
Park officials also are in the dark about how fast the sliding, cracking and deformation is occurring in many of the structures, he said.
While not a scientific measure, park rangers who give tours around the park are in a unique position to see the parks condition evolve day after day.
Paul Bostrom, an interpretive ranger who has worked at the park for 12 years, said he watched while visitors footsteps slowly wore away scrape marks where native people used to sharpen stones.
The vast majority of visitors know and abide by the rules of the park and only walk where they are supposed to, but even those repeated footsteps on the soft sandstone cause a certain amount of wear over time, Bostrom said.
At Cliff Palace, Travis and his staff have conducted a detailed analysis of the southern half of the ruins. Next, they will assess the condition and structural integrity of the northern portion of Cliff Palace and finish a culvert system that directs water from the parking lot above the alcove to drainage areas away from the ruins.
Park officials are considering several options to stabilize structures that are sliding or buckling. Potential strategies include backfilling beneath the ruins to solidify the foundation, installing buttresses or creating a more permanent set of braces to hold up walls. A new retaining wall near the ledge of the alcove also would help support the entire foundation and prevent the downward slide
Travis said the entire project will take at least two years.
The nonprofit Mesa Verde Foundation helps support the park financially and has rallied around the Cliff Palace stabilization work.
The foundation and the National Parks Foundation are working on an agreement to partner in an effort to raise $150,000 to support those efforts, said Ben Duke, the foundations executive director.
Cliff Palace is such an iconic American treasure, it is pretty hard to ignore that something is happening to it, Duke said. This (project) captured the imagination of everybody.
The preservation work happening at Cliff Palace represents a huge change in archaeological work that involves a more proactive strategy that gets at the bigger problems, Travis said. Archaeologists now combine geology, hydrology, geography and historical knowledge with sophisticated techniques like three-dimensional laser scanning and ground-penetrating radar mapping.
It has become a very technical science to manage and understand these resources, Travis said.
The park has numerous partnerships with institutions and individuals around the world that use the park as a learning laboratory. A new summer seminar at the University of Pennsylvania allows graduate students and postdoctoral researchers to learn from the work going on at Mesa Verde.
While the deterioration of Cliff Palace and many other ruins is increasing, archaeologists are able to attack the issue with a new level of sophistication, Travis said. Their goal is to re-create history.
The key in all of this, of course, is trying to preserve the original fabric, the character, the nature and the materials that constitute Cliff Palace, he said.