Conservation Considerations for Rock Art Research (2013)

With resilience to the elements and time, rock surfaces resulted to be the ideal canvas for lasting expressions of past cultures. Unfortunately, they are also accommodating for lasting vandalism, the effects of which survive indefinitely alongside original rock art. Unintentional damage often occurs in the recording of rock art. This paper explores s variety of rock art recording methods and will discuss their potential effects, especially in regard to preservation and dating potential. To evaluate which method is the least invasive and detrimental, I will provide a comparison of the benefits and effects of the most utilized manual and automatic rock art recording methods and technologies.

Introduction

This paper will discuss issues and concerns of conservation in rock art research. Rock art can be best described as human-made marks on natural, [typically] non-portable rocky surfaces (Chippindale and Tacon 2000). These marks include pictographs, which are markings that have been painted, drawn, stenciled or otherwise applied to the rock surface. Another method of creating rock art, where marks are incised, abraded, or otherwise created by removal of the rock surface, are referred to as petroglyphs. When a petroglyph is made, the patina[1] is removed to reveal a lighter contrast beneath.

There are multiple factors which must be considered including environmental, social, and economic factors, as well as concerns of vandalism. There are two general types of vandalism that affect rock art sites: deliberate and unintentional. Deliberate vandalism involves a conscious decision to alter the rock art with various methods; including graffiti, initial carving[2], looting, and target practice. Preventing deliberate vandalism is not my primary focus for this research, as the effects of deliberate vandalism are instant, and in many cases unavoidable. Unintentional vandalisms occur due to misinformation or ignorance, with adverse effects accumulating over time. Rock art recording methods are often a source for unintentional damages to rock art, so common recording methods will be analyzed with specific consideration for diminishing unintentional vandalism through a standardized recording procedure.  Research considerations such as completeness, accuracy, and efficiency of these recording methods will also be emphasized, as the quality of the record is often a justification for various recording methods.

Conservation Considerations

            There are several factors which impact theories of rock art conservation. Deacon (2006) points out that although many groups consider conservation to be a “good” reaction to detriments or vandals, there are several other points of view that must be taken into account. She asserts that rock art conservational theory is a delicate balance between environmental, social, and economic factors (Deacon 2006).

Environmental Factors

Environmental factors are Necessary to consider, due to their presence at every site. Environmental considerations for the conservation and preservation of rock art sites include: the material of the host rock surface, surrounding climate, and types of paints, pigments, or engravings used in the rock art. It is also important to consider any physical alterations from people, plants or animals, or artifacts that may be associated with the site (Deacon 2006).  Because the environment is ever present and constant at art sites even without the human element, their effects must be considered.

Dating Potential

Dating rock art is difficult, due to the uniqueness of a rock art feature. Environmental factors such as the rate of lichen growth or repatination have been used to relatively date rock art panels. Although carbon is usually present, the amounts are generally minute, and researchers have no method of knowing whether the deposits correlate with the art event (Chippendale and Tacon 2000). Accelerator Mass Spectrometry (AMS) technology has reduced the sample size necessary for dating, allowing for new experimentation with direct dating of rock art, however researchers are finding a high occurrence of contamination (Cole 1990). Much of this contamination is the result of enhancement practices, both by researchers and visitors. Enhancement methods are employed to increase contrast or otherwise prepare the rock art for recording. Many of these methods have adverse effects on the dating and preservation of rock art.

A common practice used is wetting, or applying some liquid to a rock surface. This causes the patina and accretion layers to become transparent, increasing the contrast (Chafee, et al. 1994). Even water can accelerate the process of accretions, which may affect dating potential. Another method utilized which seems harmless is chalking, in which an outline is traced around a rock art figure. These outlines can last for years, as with the All American Man in Southeastern Utah, which has maintained a chalk outline for 30 years (Chafee, et al. 1994) (Fig. 1).

 Chaffee , Hyman, and Rowe conducted a comparative analysis of accelerator mass spectrometer dating on spalls of red paint from the Holy Ghost and Attendants panel at Canyonlands National Park and found that dead carbon, carbon so old it has almost completely decayed (Chafee, et al 1994). The most common sources of dead carbon are geological carbonates (for example, limestone), and fossil fuels. A common fossil fuel that has been applied to increase contrast in rock art is kerosene. The study found that the panels had likely been contaminated with kerosene or something similar. I believe such methods can be prevented through educational outreach to both archaeology professionals and the public.

Fig.1    Chalk Embedded in Rock Varnish (Whitley 2005)

Social Factors

The social factors which should be considered for conservation include the rights of descendant communities, property owners and researchers, management policies and legislations, and public expectations and attitudes (Deacon 2006). Many legislations and management policies are dependent on who the property owner is.

Accountability may be one of the most important considerations for the protection of rock art sites. When individuals feel connected to a site, they feel a responsibility to protect it. Grant says those with private ownership of a site may be inclined to protect it more, rather than a Federal entity with no personal connection to the land (Van Tilburg 1980). This is where public expectations and attitudes become exceedingly important. These are the local individuals, rather than tourists, who may have information, time, or resources that they are willing to contribute. For example, there are site steward programs which train volunteers to periodically report on the conditions of a site (Whitley 2005).

Economic Factors and Tourism

Because it inevitably takes money to enact many conservation procedures, economic considerations include the location of the site in relation to roads, type of ownership of the site and tourism facility, tourism marketing strategies, level of income generated by tourism, and the extent to which local people lose or derive income from rock art tourism (Deacon 2006). Tourism can be very beneficial in that it generates the income needed to protect and maintain a site; however there is an increase in concern when visitor numbers increase. Concerns which may have little adverse effect in small numbers may significantly affect rock art integrity or dating potential. An example would be a significant increase in carbon deposits from campfire smoke.

            Visitors interpret the context of a site in much the same way archaeological researchers do, therefor the manner of presentation of a site to visitors is essential to discouraging vandalism, whether intentional or unintentional. A site which is free of graffiti and visitor garbage presents the image that there is a person nearby who is involved and concerned for the site. If funding permits, the ideal tourism tactic involves guided tours and educational outreach. Infrastructure such as low fences, informative signs, and visitor sign-in boxes are beneficial when funding may not provide for a guide. These still provide a perceived official presence which may detour vandals (Fig 2).

Fig.2    Ayers Rock: Car park, path, and signs built by local boy scouts (Whitley 2005)

Rock art Recording Methods

Walt and Brayer (1994) introduce two general methods for rock art recording: manual and automatic. Manual methods include some outdated techniques such as tracing, rubbing, and molding, as well as simple drawing and computer aided drawing. Automated methods include photography and more recently 3D laser scanning technology. There is also the category of non-image recording methods, which provide important contextual data for researchers.

Criteria for Analysis

            The ideal methods for rock art recording will reflect a high degree of accuracy and efficiency, and will maintain little to no conservation considerations. For this analysis, accuracy is defined in terms of scale, context, and location. How well the resulting data reflects reality. Efficiency is concerned with the cost of executing a specific method, with regard to monetary cost, labor, and field logistics. Conservation considerations reflect any adverse effects of the recording on the data itself, or the potential for future data.

Manual Recording of Rock Art

Manual methods have been used for long time in rock are recording, due to being rather inexpensive and require relatively little training. The advantage to manual recording is that a researcher is able to subjectively alter the result to improve the context. This is also a disadvantage, as there is no standard procedure and interpretations may differ among researchers. The final result is dependent on the skills and interpretation of the recorder, and thus the reflection of reality at the site is subjective.

Tracing, Rubbing, and Molding methods are increasingly becoming phased out among researchers, due to the fact that they involve contact with the rock surface. It is now known that contact can have gradual effects on the preservation and even on chronometric dating possibilities. Rubbing can alter the rate of repatination and may further abrade some surfaces. Because there are several non-invasive technologies available, they should be considered prior to any of these practices.

Fig.3    Recording by Rubbing: not recommended due to its invasive nature (Rock Art Pilot Project 2000)

Drawing

Drawing by hand has a great advantage in that it is inexpensive and requires little equipment. As stated above, the recorder’s contextual interpretation can be helpful; however this subjectivity can be a disadvantage. A good drawing will also be time consuming in the field. Drawing by hand is a good method for conservation concerns, as it avoids contact with the rock surface (Walt and Brayer 1994).

A standardized graphic system may be employed for drawings, and should include a key (Fig 4). This will remove some of the confusion often encountered when recorders on a project have a different symbology system. A string grid may also be employed to aid in scale representation; however care should be taken to avoid contact with the panel surface. It should be noted that he grid works as a guide at best, and the interpretation is still in the hands of the recorder (Whitley 2005).

Fig.4    Graphic Conventions (Whitley 2005)

 Automated Recording of Rock Art

Automated recording methods employ mechanical means to capture rock art imagery. These methods include photography, computer aided drawing, and 3-Dimensional scanning. The advantage to automated recording is a non-invasive approach. The primary disadvantage is the cost, especially with newer technologies.

Photography

Photography has been the primary recording method for rock art researchers, because it is non-invasive and now extremely efficient with the invention of digital cameras. A concern with photography is lighting, as many rock art sites are included in caves or otherwise covered (Whitley2005). The ideal natural light conditions will be light to medium overcast. Bright sun has the disadvantage of causing too much contrast and shadow (Walt and Brayer 1994). Early morning or late afternoon provide softer lighting, which may produce a better color photograph (Walt and Brayer 1994). Flash technology should be avoided, as it may have adverse effects on fragile art surfaces. In some rock art sites, for example those in caves, it may be near impossible to record any data without the use of portable lighting equipment.

Digital photography trumps standard photography in regards to efficiency. Standard photography requires processing out of the field, where with the digital technology; the researcher can see and review the image in the field. A concern with photography is that in transferring a 3-dimensional reality into a 2-dimensional representation distortions may occur. This accuracy may be improved by researchers taking specific note of weather conditions, time of day, and angle of the photograph.

Computer Aided Drawing

            A photograph is printed lightly and then retraced by the recorder (Walt and Brayer 1994). This allows for any annotations of superimpositions, or significant rock features. An option that has become available with technological advances would be to use a portable tablet with touch-drawing capabilities. A photograph can be uploaded with a transfer cord, and a researcher can draw directly on the screen. This method is beneficial in that it combines the efficient instant capture of digital photography, with the ability to add in specific annotations or contrasts that may not reveal well. This is a good method in regards to conservation because it is completely non-invasive (providing natural lighting is used).

3-Dimensional Photogrammetric Scanning

            3D scanners sweep lasers over a surface and calculate a digital elevation model based on the time it takes the beam to reflect back (Walford 2009). Scanners maybe mounted, or handheld units. Photogrammetric scanning uses a digital camera and software to create a 3-Dimensional model. The advantages of a laser scanner are the record is able to accurately reflect the contours of the rock surface. Accuracy is impacted by the quality of the camera used however, so the highest resolution possible should be used (Walford 2009). A primary disadvantage of this method is the cost. Tripod and handheld scanner units can be pricey, and may take time in the field for set up. Scanning time may fluctuate, depending on the number of control points, as with processing time. The resulting model is very accurate, in some cases revealing more than researchers are able to see.

Non-image recording methods

Recording methods such as Global Positioning Systems (GPS), Geospatial Information Systems (GIS), database programs, sketch maps and rock art record forms may not provide the image of the rock art itself, but provide important context for interpretation and conservation in a regional context.

Global positioning systems (GPS) provide spatial information via a satellite tracking system. A monitor control unit is held by an individual, which uses satellite triangulation to formulate the spatial position of the unit. Accuracy is of primary concern when using a GPS, as there is a dilution of precision depending on the reliability and quantity of satellite configuration. There are units which are capable of recording positions with sub-meter accuracy, however these increase in price. Typically, a unit costing around $200 can reach 3-5 meters accuracy, with more expensive units reaching sub-meter ($800+). Some newer models even offer Bluetooth connections for more efficient data collection. When recording spatial information with a GPS, the operator should note number of satellites, and the dilution of precision, as well as which coordinate system is being used for reference (in some cases the software may do all of this).

Geospatial Information Systems (GIS) are computer based systems assisting the collection, analysis, and display of spatial data and information (Bolstad 2012). They are often utilized for data distribution and cartography, which is especially beneficial for archaeology. Because a GIS can analyze spatial data along with aspatial data, it is an ideal tool for predictive modeling. The location of a panel can be displayed on a base map, with attribute table listing data such as type of host rock surface, number of individual motifs on panel, technique (painted or pecked), condition. The data in an attribute table can be used for predictive modeling, by using a Structured Query Language (SQL) search. The results of which can be displayed in reference to known spatial coordinates. GIS work well when joined with data in tabular format. There are numerous database Programs[3] available which can be easily imported to an attribute table.

Sketch maps provide the benefit of reflecting the subjective view of a researcher who is present in the field. They provide a snapshot view of the context and condition of the site at the time the research is present. Elements which are essential to a sketch map are a north arrow and scale, the recorders name, date and a legend describing symbols used.

Rock art record forms implement a measure of standardization into the rock art recording practice. The IMACS rock art recording form, for example, provides data categories including: number of panels at site, host surface type,[4] direction of worked surface, [5]type of rock,[6] background[7], category and technique, and degree of repatination.

Ethical Considerations in Rock Art Recording

There are disagreements on whether rock art sites should even be preserved. These sites offer important contextual data for researchers, who agree that restricted access and closures may be necessary for some sites that may be especially fragile due to their size, rarity, religious importance, or other factors (Whitley 2005). The issue here is that it makes the researcher the elite authority on who is qualified to visit a site, and fails to consider the opinions of the public. Another opinion is that although these ancient images were created for a specific purpose, that purpose belongs in the past and once fulfilled the images need not exist (Tilburg, et al. 1981). If researchers are to continue recording rock art sites, some form of standardization must be employed.  These standards should employ non-invasive methods (computer aided-drawing, photogrammetric scanning) along with non-image recording technologies.

Bibliography

Bolstad, Paul

2012     GIS Fundamentals 4th Edition: A first text on GIS. 4th ed. White Bear Lake, MN: Eider.

Chaffee, S. D.; Hyman, M.; and Rowe, M. W.

1994     “Vandalism of Rock Art for Enhanced Photography”. Canyonlands Research Bibliography. Paper 148.

Chippindale, Christopher, and Paul S. C. Taçon.

1998     The Archaeology of Rock-art. Cambridge, U.K.: Cambridge UP

Cole, Sally J.

1990     Legacy on Stone: Rock Art of the Colorado Plateau and Four Corners Region. Boulder, CO: Johnson.

Deacon, Janette

2006     Rock Art Conservation and Tourism. Journal of Archaeological Method and Theory, Vol. 13, No. 4, Advances in the Study of Pleistocene Imagery and Symbol Use [Part I]

U.S. Department of the Interior National Park Service.

1988     Management Policies.

 Marymore, Leigh

2001     ARARA Guidelines for Managers of Rock Art Sites on Public Lands. Prepared for ARARA Conservation and Protection Committee.

Rock Art Pilot Project (RAPP)

2000     Rock Art Pilot Project. Main report: Figures and Tables. Bournemouth and London. Bournemouth University School of Conservation Sciences and University College London Institute of Archaeology for English Heritage. [Limited circulation printed report]

“Utah State History.” IMACS Manual. http://anthro.utah.edu/labs/imacs.php

Rock Art Attachment Form

Section 510

Van, Tilburg JoAnne, and Clement W. Meighan

1981     Prehistoric Indian Rock Art: Issues & Concerns: Report of the 1980 Conference Proceedings, Institute of Archaeology, the Rock Art Archive, University of California, Los Angeles. Los Angeles: Institute of Archaeology, University of California, Los Angeles.

Walford, Alan

            2009     A New Way to 3d Scan. Eos Systems, Inc.

Walt, Henry, and John Brayer

1994     A Petroglyph Recording Demonstration Project for Petroglyph National Monument.

Wasklewicz, T., Whitley, D., Volker, H., & Staley, D.

2005     3D Laser Scanning and Intensity Mapping: A New Methodology for Mapping and Monitoring Rock Art Sites. International Newsletter on Rock Art, 41

Whitley, David S.

2005     Introduction to Rock Art Research. Walnut Creek, CA: Left Coast.


Footnotes

[1] Patina is the accumulation of elements on a surface over time.

[2] Individuals feel the need to mark that the have been at the site as well, and carve their name or initials.

[3]  Microsoft Excel is one of the more common programs.

[4] Bedrock, boulder, cave interior, cliff-face, portable-small stones, rockshelter interior, structure (IMACS Manual Rock Art Attachment form).

[5] Vertical, horizontal, sloping, overhead, multiple (IMACS Manual Rock Art Attachment form).

[6] Basalt, granite, limestone, sandstone, tuff (IMACS Manual Rock Art Attachment form).

[7] Natural, painted, patinated, plastered, smoke blackened (IMACS Manual Rock Art Attachment form).


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