Unravelling the Gordian Knot: Integrating Advanced Portable Technologies into the Analysis of Rock-Art Superimposition

Lead Research Organisation: University of Central Lancashire
Department Name: Sch of Forensic and Investigative Sci


For thousands of years and across the globe, humans have painted images in caves and on other stone surfaces. Some painted sites were later revisited by people who added new paintings on top of the older. Such sites can be very colourful, complex assemblages of paintings placed one on top the other, so much so that it can be very difficult to discern the sequence of painting over very long periods of time. While archaeologists have developed many sophisticated theories to interpret these paintings, and pieces of the paintings that have fallen off may be recovered to analyze in a laboratory, until recently it has been very difficult to analyse the paintings using powerful scientific equipment while the paintings remain on the rock surface. However, technolgoical advances have produced small transportable devices which now allow for detailed on site analyses that do not harm the paintings. These non-destructive portable technologies can scan the cave, rock-surface, and paintings in 3-Dimensions; can use X-ray technology to determine the chemical elements used to make the pigment that makes the painting; laser instruments to identify organic components of the paintings; and can use portable digital photography to reveal hidden layers normally barely perceptible to the human eye. Unravelling the Gordian Knot Project will apply all of these methods to analyze the spectacular and colourful paintings at the site called Pleito, found in California, USA. Pleito is one of the most complex painted sites in the world. It has hundreds of individual paintings with many colours, including different shades of red, black, white, yellow, orange, green, and blue. This is the widest colour palette of any known site in North American and, importantly, it has multiple panels where paintings have been placed over earlier ones. This kind of overpainting, known as superimposition, presents the greatest challenge to rock-art researchers in their attempts to understand painted art found in the landscape. Even though such complex paintings are challenging, they offer to the archaeologist who can unravel the sequence the greatest chance of understanding the development of paintings through time. Within the site of Pleito, a panel known to researchers as the 'Gordian Knot' is the most elaborate panel found there, making it one of the most complex prehistoric panels found anywhere in the world. The name of this project is derived from this panel, and so Pleito and its complex sequences of overpainting executed in various colours is an ideal case to disentangle the history of painting events. The method employed will integrate a range of portable technologies including portable X-Ray Fluorescence, portable Raman Spectroscopy, Highlight Reflectance Transformation, dStretch digital photography, and portable digital laser scanning to unravel the sequence of painting that makes up one of the most complex sites found anywhere in the world. These techniques will help address questions concerning traditions of pigment use and give insights into the role of the art within Native society. The project includes a state-of-the-art website with a 3-D recreation to be housed at the California State University, Channel Islands, offering an alternative to site visitation as a means to experience the site without risk of damaging the ancient paintings. Also, a new conditional assessment will compare degradation of the site to a 2003 baseline report to see how much of the paintings have recently eroded away: finally, a series of experiments combining different pigments with different types of binding agents will give us material to test with both lab based and portable equipment in the creation of a spectral database: this will give us a series of different chemical readings to compare with the actual paintings and allow researchers across the world to compare results from their discoveries with the Gordian Knot Spectral Databasee

Planned Impact

The Gordian Knot Project will have impact across a wide range of different audiences:

Website: This website will be a vehicle for impact including A) Virtual Reality Remote Site Experience; B) Multiple Narrative Viewpoints; C) Spectral Database access; D) Native American Voices; and E) Management Options.
This website will be designed with will include a virtual reality 3-D model of the site and the rock-art, and maintained at the California State University, Channel Islands. Derived from the 3-D scan data, layer separation graphics from Photoshop, and data from the pXRF and pRaman, a virtual reality model complete with specific dropdown menu options for panels, sequences, and individual element compositions will be created. Individual panels and the layers comprising them will be able to be explored, with chemical descriptions in lay and technical terms provided. This will allow for anyone with internet access the opportunity for a virtual experience of the site without the potential harm to the paintings that physical access risks. The inclusion of two optional narratives: one a lay narrative, the other containing the technical data, will allow for users with different needs and levels of knowledge to comprehend the results of the project. Equally, the site will house the Gordian Knot Spectral Database - a comprehensive list of the results of the spectral work which will be usable for researchers across the globe. With its permanent housing, future data will be able to be added, thus making it an expandable data base and add lasting project legacy. Another feature of the site will include a Native Americans Voices page, thus providing a venue for this important stakeholder group that often does not find a place in academic research for input: this section will include voice and video interviews with the local Native American groups to promote indigenous perspectives on the site and its importance within local traditions. Conservation ethos: The main ethos of the website will be to promote conservation and long term care of Pleito as an example of a precious, world class rock-art site to promote long term changes in the attitudes of the general populace in terms of site preservation. This ethos reflects the Wind Wolves Preserve mission statements of preservation and conservation of the natural environment. The website will also act as a management tool to mitigate visitation while promoting the long term aim of preservation of both the site and other archaeological sites found on its property.

The Gordian Knot Project will also provide a site management plan to the Wind Wolves Preserve in order to more fully protect Pleito in the long term. In 2003, the Rock Art Documentation Group (RAD Group) published a technical conditional assessment of the pictographs and the host rock. The RAD Group will work with The Gordian Knot project as consultants to reassess the site: this will give us an assessment of the potential damage that has occurred to the site in the intervening decade. Robinson and Perry have extensive experience with Cultural Resource Management reports and the site will edited the final report before submission to the Wind Wolves Preserve. The report will include management recommendations for the long term preservation of the site. In addition, the project will produce a pamphlet outlining the archaeology of the Preserve and the importance of conservation for a younger, non-academic audience. This pamphlet will be written by Robinson and Perry, and will include. A pdf of the brochure will be provided for the preserve so that it may use in its educational program.

The project will work closely with B&W Tec to aid in the refinement of future portable spectral technologies. A white paper outlining this will be made freely available on the Gordian Knot Website and we will apply for further funding to host a conference to reach a broad spectrum of UK professionals.