The effort to record and preserve archaeological evidence in the Red Rock District is an ongoing process that benefits from advancements in photographic technology. The Sedona Friends of the Forest have volunteers who document local archaeological sites and evaluate the natural processes and human vandalism impacting the sites.

Some of the Native American rock art and structures have been in place for hundreds and in some cases, thousands of years. Natural wind and water erosion clearly impact the sites, but recent evidence indicates that increased visitation is also having a negative effect.

Graffiti incidents at the Palatki, Honanki and V Bar V heritage sites have irreparably damaged ancient pictographs and petroglyphs. In addition, volunteers and researchers at these and other sites believe that many of the Archaic, Sinagua and Yavapai pictographs are noticeably faded, compared to how they appeared in the past. There is a concern that if this is valid and identifiable after only a few decades of observation, the natural degradation process may have been quickened by human impact.

One theory is that ancient pictographs at Palatki and Honanki are being visually degraded by coatings of dust raised by increased vehicular and foot traffic. Videos of vehicles entering Palatki at different speeds indicate increasing amounts of dust thrown into the atmosphere with increasing speed. If vehicles are traveling over 10-15 mph while there are winds from the south, dust is clearly being carried up to the rock art alcoves. To evaluate this theory, we have begun a Dust Study Project at Palatki and Honanki.

The Friends of the Forest photography team has taken baseline photographs at each site under precisely controlled conditions. The photographs include a color calibration chart commonly used for scientific evaluation of color change. In addition, a volunteer artist created modern versions of ancient style pictographs using traditional materials and techniques. These have been put in place at the sites and photographed using a very precise procedure.

Among the benefits of using modern versions of ancient styles is that visitors to the sites can see how ancient pictographs may have looked in terms of brightness and depth of color compared to those that have been weathered for hundreds or thousands of years.

We periodically take a new set of photographs. We then compare the color and luminosity values of specific areas of the pictographs to determine changes over periods of months and eventually years. This process requires significant effort and learning curve by volunteers at the site doing the photography and evaluation afterwards using detailed software processing. We expect initial results of the project to be available later this year. The project will continue indefinitely to determine cumulative effect over time.

Friends of the Forest is continuing to document as many sites in the region as possible for future reference, with over 400 sites having been photographed in detail, resulting in approximately 100,000 photos. As a result of these efforts, we have identified many issues regarding the sites.

Application of Dstretch, RTI, and 3D techniques are now used on a regular basis as part of the documentation process.

Dstretch is a software process that allows archaeologists to see modified color spectra of pictograph panels. This in turn allows us to identify details that cannot be seen under normal circumstances or in regular photographs. The lesson learned from applying this process is that in all cases, cliff rock faces should never be touched, as there is a real possibility that there are essentially “invisible” ancient pictographs present. To date, over 1000 otherwise invisible pictographs have been identified. In many cases they are in direct association with known rock art, but is some cases they have been identified on what were previously believed to be archaeologically sterile rock faces.

RTI or Reflectance Transformation Imaging is a technique to provide very detailed documentation of small-scale rock art and artifact material via interactive 3D lighting of finely detailed subjects. RTI is now one of our standard documentation tools.

The Friends of the Forest photo documentation project continues to acquire and use 3D photo modeling, with over 1,250 3D models now available for public review at Application of this technology and review of the resulting models has shown many details of Sinagua dwelling walls and rock art panels that can’t otherwise be seen. We encourage you to visit the site and explore the 3D models.

The culture heritage of our native ancestors is one of the great benefits available to us in the Red Rock District. We are continuing to do everything possible to preserve and study that heritage.

Serving Sedona, written this week by Spence Gustav of Sedona Friends of the Forest, appears Wednesday in the Sedona Red Rock News.