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    Mesa Verde

    National Park Colorado

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The Preservation of Cliff Palace

Cliff Palace within its alcove
Cliff Palace
NPS PHOTO
 

Since its 'discovery' in 1888 Cliff Palace has been the focus of early exploration, commercial exploitation, archeological investigations, and generations of visitors to Mesa Verde National Park. Throughout this history the imposing structure has also seen the development of innovative preservation strategies designed to halt and stabilize the continuing effects of natural and cultural agents of deterioration. As the centerpiece of Mesa Verde National Park, it remains one of the finest examples of a late prehistoric cliff dwelling in the American Southwest.

Cliff Palace challenges visitors to imagine what life was like over seven hundred years ago. Constructed of stone masonry, wood, and earth covered with plaster painted in a variety of colors; the structures that compose Cliff Palace reflect traces of everyday events: the mundane chores of food preparation and storage, private and public spaces, concern for defensive protection, village organization, and solemn ritual. These same buildings and spaces also reveal intentional design, subtle details of craftsmanship, and reliance upon construction materials and methods (structural systems) in use for hundreds of years. Collectively, these two views of Cliff Palace provide a way of understanding the past and the challenges we face at present to preserve this ancient place.

 

Centuries of Deterioration

 
Cliff Palace before excavation, c. 1890 to 1900.

Cliff Palace, pre-excavation c. 1890 - 1900

THOMAS MCKEE PHOTOGRAPH COLLECTION, MEVE 9084, TM-36

From the late 13th century to 1880s, Cliff Palace slowly deteriorated from the effects of water, wind, freeze/thaw cycles, differential fill levels, a variety of animals, spalling of the alcove roof, and the inherent qualities of the prehistoric structures themselves. Over the course of six centuries, Cliff Palace was visually transformed from an imposing assemblage of buildings, courtyards, and subterranean kivas to an array of stone structures rising from tons of rubble and debris. Still remarkably impressive, the effects of time were nevertheless evident. However, with the 'discovery' of Cliff Palace in the late 1800s, this gradual process of decay rapidly accelerated. Casual visitation and commercial exploration employed everything from pick and shovel to dynamite in an effort to recover all types of artifacts. In the end, the form and fabric of Cliff Palace was heavily damaged throughout its extent, with the natural processes of deterioration now altered by human activity.

With the establishment of Mesa Verde National Park in 1906, the despoliation of the late 1800s was replaced by an emerging preservation ethic determined to halt the damage. Through the efforts of Smithsonian archeologist Jesse Walter Fewkes, field methods designed to excavate and collect artifacts were modified to identify and understand the effects of unrestrained looting upon standing architecture, buried features, and archeological deposits. In addition, Fewkes realized the importance of preparing archeological sites for visitation. He believed it was only through direct experience, literally being able to walk through a cliff dwelling, that the American public could appreciate and support the preservation of Mesa Verde's archeological resources. To accomplish this goal, Fewkes, along with many of his contemporaries, invented the practice of ruins stabilization. Although certainly limited by the use of incompatible materials, construction techniques, and somewhat fanciful reconstructions, there seems little doubt that the history of ruins stabilization within Mesa Verde National Park fundamentally contributed to the development of contemporary Conservation Archeology.

 

Today's Preservation Needs

 
Visitors encircling Kiva F during a ranger-guided tour of Cliff Palace

Visitors encircling Kiva F during a ranger-guided tour of Cliff Palace

NPS PHOTO

As the largest and most famous cliff dwelling in Mesa Verde National Park, Cliff Palace is the park's interpretive centerpiece. Many of the half million visitors each year make it a point to stop and see Cliff Palace, either through magnificent views from one of the nearby overlooks or by taking a ranger-guided interpretive hike into the cliff dwelling itself. Until recently, one of the key components of a Cliff Palace interpretive tour was Kiva F, a 13th century circular structure located in the southern portion of the alcove. Partially subterranean, the structure was built on top of loose fill, sandstone slabs, and cultural debris. Surrounding Kiva F are Kivas C and G, an assemblage of multistory rooms, and retaining walls that ascend toward the back of the alcove. As each ranger-guided hike (on average 15 tours and 740 visitors per day or roughly 3,962 tours and 160,600 visitors per year ) moved through the site, they walk up a short set of steps and stand around Kiva F on a heavily stabilized pathway. Here the ranger discusses the character, function, and significance of a kiva to the Ancestral Pueblo people, and visitors have the opportunity to spend a few moments in thought. It was during one of these hikes in early summer, 2011 that a ranger observed what appeared to be a problem.

 
Cliff Palace. Dual photos temporary stabilization of Kiva F

Kiva F at Cliff Palace. Top: Leaning north wall.  Bottom: Temporary brace to stabilize wall.

NPS PHOTO

Just below the stabilized path, a small void had appeared in the masonry bench or banquette accompanied by the north wall now leaning precariously into the structure. In response, National Park Service archeologists began an evaluation of Kiva F to determine overall condition and potential causes. The team reviewed previous preservation treatments that had addressed water penetration, localized cracks, displaced segments of wall, and loss of mortar and stone. They then examined the void and extent of wall deflection, and weighed various options to stabilize the problem. As a remedial measure, a wooden brace was installed to support the north wall over a weekend, and the ranger-guided hikes were re-routed to avoid Kiva F.

When the team returned the following Monday, they were confronted with a more complex problem. While they focused on the north wall of Kiva F, a large portion of the south wall unexpectedly fell onto the Kiva floor. With no prior indication of an impending collapse, this event suggested underlying conditions that extended far beyond the structural boundaries of the kiva, potentially threatening much of the southern half of Cliff Palace. Further assessment of the surrounding structures, notably Kiva G just to the north of Kiva F, further reinforced these observations. What followed was the decision to expand the scope of investigation beyond Kiva F to include more detailed study of earlier stabilization efforts, comprehensive condition assessment of 102 architectural units (roughly the southern half of the site), and yet another look at the long-standing problem of water entering the alcove through cracks on the mesa top above Cliff Palace.

 

Assessment Results as of July, 2012

 

After months of exhaustive study, it now appears that both localized deterioration of individual structures and features, as well as site wide systemic problems indicative of structural failure, are working in tandem.

  • Localized effects include loss, or substantial damage of stone, wood, mortar, and plastered/painted surfaces; compromised foundations; damaged architectural features (e.g. doorways, vents, wall niches, wall pegs, etc.); relatively small to severe wall cracks; and partially collapsed walls. These conditions are the result of both natural and cultural processes affecting the fabric of Cliff Palace in a fairly predictable, widespread manner. These same processes, however, can affect standing architecture and site deposits in different ways; as in the rate, magnitude, character, and distribution of specific problems. A simple example of this would be how one piece of sandstone remains intact while the one next to it crumbles into powder.
  • Systemic problems, while more difficult to detect, pose an equal or greater threat to the preservation of Cliff Palace. Our studies now suggest that much of the architecture in the southern portion of the alcove is predominantly footed onto small, irregularly shaped roof slabs or unconsolidated alcove deposits spread across a steeply pitched alcove floor. Over time these deposits, and the structures built on top of them, have begun to 'slide' downslope. This process may be gradual, rapid or a combination of the two. Evidence in the form of a distinct linear crack and significant structural deformation extends from Kiva A at the south end to Kivas F, G, and H at the center of the alcove. In effect, what we see is a fault line running parallel to the back of the alcove that may indicate a difference in the rate and magnitude of movement above and below the line. Further complicating the picture is the likelihood that a few larger roof slabs on the alcove floor provide a more stable footing for some structures, and thereby create both vertical and lateral thrust working to literally tear prehistoric structures apart. Large cracks, structural deformation, and rapid collapse - as illustrated in Kivas F and G - support this interpretation.

While the collapse of Cliff Palace is not imminent, the combination of ongoing deterioration of individual features and structures along with an unpredictable foundation will eventually result in loss of architecture and archeological deposits. Fortunately, the cracks, voids, and leaning walls noted above provide critical clues to understanding what is causing the deterioration, how quickly it is occurring, if it is happening throughout the site or only in specific areas, and what steps we can take to slow or stop the process.

 

What's Next

 

The next steps include:

1. Completion of a comprehensive condition assessment in the north half of Cliff Palace
2. Careful study of preservation history and treatments
3. Geological and hydrological analysis of the alcove
4. Structural analysis of architecture
5. Installation of monitoring systems
6. Modification of visitor management objectives
7. Development of alternative preservation treatments
8. Preparation of an Archeological Site Conservation Plan

 

Please note: This page will be updated as more information is discovered. (Last updated, 08/14/12)

Did You Know?

A view from Park Point overlook

Park Point, the highest elevation in the park (8427 ft/2569 m), has a 360 degree panoramic view that is considered one of the grandest in the country.