Saturday, July 14, 2018


5DT813, Panel 1, composite of 4
tracings, Photo and drawing from
Carol Patterson.

I would suppose that most of us have been involved to some extent with recording rock art. If so, you have to be aware that the least controllable aspect of any such project is the drawing of the rock art panel. Drawing is still vitally important because we can always see things on the rock surface that the camera does not pick up. However, in the rock art recording projects I have done some of the volunteer recorders turn in really poor drawings that look like they were done by a child. Not everyone has had training in close observation and drawing.

I have recently had the pleasure of reading the 2006 report on the rock art of Eagle Rock Shelter (5DT813) done by Dr. Carol Patterson and Dr. Alan Watchman, and I was struck by the high quality of the documentation produced. I am especially impressed by the quality of the drawings of the rock art panels that they included with all the photographs in this report. I want to pass on to you the process they used and show some examples of the remarkable quality they achieved.

 5DT813, Panel 8 complete.

5DT813, Panel 8, left side.
5DT813, Panel 8, right side.
Drawings and photos from
 Carol Patterson.

"The documentation of the Gunnison Gorge rock art site was conducted in a systematic manner that employed site mapping, drawing of the plan and elevation, ink drawings and GPS recordings. Colorado State Historical Society forms were completed for each panel. Digital and film photography was used for recording each panel. The petroglyphs are very difficult to see, and film photography would not reveal enough detail for quality reproductions. Black and white photographs were taken for archival records, but the very faint paint remnants are not visible in this format. Digital photographs manipulated in Adobe Photoshop for color enhancement revealed the remnant red paint on several panels. The whole site is basically weathered sandstone with engravings covered with dust and encrustations combined with some areas that are chalked, rubbed from cattle, spalling, and washed by rain and affected by seepage and algal growth." (Patterson and Watchman 2006:23)

This, in itself, exceeds the standard for many rock art recording projects, but this is just the beginning for Carol and Alan in their determination for accuracy in the final record.

 5DT813, Panel 16, close-up.

5DT813, Panel 16, Photo and
drawing from Carol Patterson.

"The techniques used for documenting the rock art were as follows:
1. Systematic digital photographing of each panel, at the same distance and at right angles to the panel to produce a color reproduction of the entire panel. Some panels required two or more photographs to capture the entire panel. Each photograph included a distance and color scale.
2. These images were downloaded to a computer and processed through Adobe PhotoShop 7.0 and adjusted to reduce the glare and increase the contrast. This improved the visibility of the petroglyphs that had been obscured by dust and reflections.
3. Each panel was printed out and put into a plastic sleeve with a second and third layer of plastic over it. Drawings were then made on the plastic in the field as described below." (Patterson and Watchman 2006:23)

Then the actual drawing on the plastic sleeves is described as follows: "Each panel printout in its plastic sleeve was put on a clip board and taken back to the field. In front of the petroglyph panel, the color photograph was traced on the plastic sleeve. The first sheet of plastic was labeled 'geology' and on it was drawn the rock features, cracks, spalling and scratches. The second sheet was labeled 'chalk' and the chalked areas were reproduced on this sheet. The third and last sheet over the petroglyph was labeled 'petroglyph' and with a 'pecking' motion, a dot was placed in every single pecked mark that could be seen on the photograph and check(ed) on the panel surface. The resulting ink drawings on plastic were then scanned to produce a single graphic representation of the panel. The plastic sheets were assembled to produce a full reproduction of each panel, including cracks and notes about threats to the panel, or scanned separately to obtain specific information about each panel." (Patterson and Watchman 2006:23)

               5DT813, Eagle Rock shelter,
               photo from Carol Patterson.

Notice that the drawing is done by tracing the photograph of the panel while in front of the panel to that each detail can be double checked against what is actually there, but various aspects of the panel are drawn on different sheets of plastic so they can be examined separately if so desired. Doing final scans of each sheet separately, and then combined, seems to me to be a wonderful way of recording all aspects of the rock art panel and combining the accuracy of tracing off of a photograph with the ability to detect details and subtle variations by human observation of the actual rock art.  

Variations of this technique could be used for rock art panels in different situations: for instance figures with both painting and pecking could be recorded with the paint and pecking on different plastic sheets so the differing techniques could be studied separately and then combined as well. Elements of a rock art panel from different cultures and ages could be easily recorded separately but then also presented in combination. Another variation that Carol has tested is to use colored pens on the different layers to bring out differences more clearly.

While working to this standard would obviously take more time than by usual methods, the results are clearly worth it. The beautifully detailed resulting drawings, with their separate layers of information, allow study at a deeper level and finer factual analysis than those of most reports. Well done!


Patterson, Carol, Dr., and Dr. Alan Watchman
2006 Gunnison River Rock Art Site (5DT813), Delta County: Documentation, Evaluation, and Management Plan. Submitted for Julie Coleman, BLM Archaeologist, BLM Field Office, Montrose, CO, 80401, Urraca Archaeological Services, Montrose, Colorado

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