An initial investigation into aspects of preservation potential of the Bradshaw rock-art system, Kimberley, northwestern Australia.

An initial investigation into aspects of preservation potential of the Bradshaw rock-art system, Kimberley, northwestern Australia. The Bradshaw rock-art system comprises a complex, unique andremarkably advanced form of art, signifying the work of highly skilledartisans. The paintings, unique to the Kimberley, northwestern Australia(FIGURE 1), possibly represent the world's largest concentration ofrock art (c. 100,000 sites). The large number of paintings indicates anexplosion of artistic creativity. Bradshaws are extraordinarily advancedboth in technique and breadth of style (Michaelsen et al. 2000; FIGURE2). Bradshaw art depicts human-like figures, characterized by extensiveheaddresses and elaborate body ornamentation. They have been classifiedinto four associations (modified from Walsh & Morwood 1999), whichvary according to detail of ornamentation and stylization styl��ize?tr.v. styl��ized, styl��iz��ing, styl��iz��es1. To restrict or make conform to a particular style.2. To represent conventionally; conventionalize. of figures: 1Tassel; 2 Sash; 3 Elegant Action; and 4 Polychrome pol��y��chrome?adj.1. Having many or various colors; polychromatic.2. Made or decorated in many or various colors: polychrome tiles.n. Clothes Peg Figures(see www.bradshaw.dk). [ILLUSTRATIONS OMITTED] Bradshaw panels are associated with King Leopold Sandstone(Michaelsen & Ebersole in press), painted on exposed, near-verticaloutcrops or in small rock-shelters. Many are shaded from directsunlight, demonstrating the painters' preference for protectedlocations. They are predominantly executed in hues ranging fromreddish-brown to crimson. A large proportion are characterized by a highdegree of weathering. In this note we summarize preliminary research of preservationaspects of the Bradshaw rock-art system. Is weathering of Bradshawpanels significantly influenced by a characteristics of the host rock,including geographical location, grain size, strike, sorting, dip,sedimentary structures and bedding thickness, and/ or b characteristicsof the method of paint application, as in undercoating or paintcomposition? The database for this study consisted of 66 Bradshaw panels,documented between August and September 2000. Degree of weathering ofeach panel was ranked on a scale from 1 to 5: 1 very well-preserved (8);2 well-preserved (16); 3 moderately-preserved (21); 4 poorly-preserved(16); 5 very poorly-preserved (5). Data analysis has indicated thatpaintings on the fluvial flu��vi��al?adj.1. Of, relating to, or inhabiting a river or stream.2. Produced by the action of a river or stream.[Middle English, from Latin plain have a higher proportion ofbetter-preserved paintings than those areas near the present coastline.Preliminary Analysis of Variance found no statistically significantdifference between differentially weathered panels in terms ofgeological characteristics. It could be concluded that no significantcorrelation exists between the geological aspects analysed and thedegree of weathering exhibited by Bradshaw paintings in this sample.However, additional investigation has indicated that somenon-significant linear relationships may exist. These factors will beanalysed in greater detail in a future contribution. The lack of correlation suggests that the nature of the paint mighthave had a profound influence on preservation. In this context, thequestion of painting materials and technique has hitherto received verylittle attention. Experimental research utilizing paint substancesidentified in the literature indicates that, without a binder, thesemixtures do not have the permanence required by the suggested age of theBradshaws (Roberts et al. 1997; Watchman et al. 1997). When applied towell-sorted, medium-grained, quartz-rich sandstone, they wash off almostimmediately with water. Further work has identified possible paintconstituents that could have been utilized as a medium, as one of themajor requirements appears to be presence of enough binder to render thepaint water-resistant after drying. Subsequent mineralization could thenact to preserve a latent image in the rock, whilst acting to remove allor nearly all of the initial binder. We are currently studying the chemical and physical mechanisms ofthe intricate interplay of climate and weathering. Precipitation islikely to be highly important as both the vehicle and the implement ofchemical and physical events that eventually `petrified' andsubsequently preserved the Bradshaws. Other possible aspects oflithology li��thol��o��gy?n.1. The gross physical character of a rock or rock formation.2. The microscopic study, description, and classification of rock. and microenvironment microenvironment/mi��cro��en��vi��ron��ment/ (-en-vi��ron-ment) the environment at the microscopic or cellular level. may have played an important role inpreservation of the paintings (e.g. Stanton 1998; Pope 2000). Our workalso reveals that some Bradshaws were preserved through episodes ofoverpainting and restoration (FIGURE 3). [ILLUSTRATION OMITTED] The question of how the Bradshaw paintings were preserved isfundamental in the attempt to date them. Our working model for paintingpreservation is based on the idea that primary damage caused by naturalforces occurred when the paint was still relatively fresh and thussusceptible to forces of erosion and similar processes. Subsequently,incorporation of the paint layer into the rock by crystallization wouldminimize the impact of weathering on the painting. Preliminary dataanalysis appears to support this concept. Some Bradshaw panels appear to have been vandalized. Scars,possibly created by thrown stones, are evident in some panels (FIGURE4). Approximately 9% of Bradshaw panels have been damaged to someextent. All Bradshaw associations, except for Elegant Action Figures,have indications of possible vandalism for reasons that are unclear, butmay include aspects of ritual mutilation MutilationSee also Brutality, Cruelty.Mutiny (See REBELLION.)Absyrtushacked to death; body pieces strewn about. [Gk. Myth.: Walsh Classical, 3]Agatha, St.had breasts cut off. [Christian Hagiog. or defacing. Superposition su��per��po��si��tion?n.1. The act of superposing or the state of being superposed: "Yet another technique in the forensic specialist's repertoire is photo superposition" ofmore recent images is another common form of vandalism, or conversely aform of preservation, and is developed throughout the Kimberley. It can be concluded that the Bradshaws clearly deserve a prominentposition in global art history. However, numerous questions remainunanswered. We hope they can be resolved with further research. References http://www.bradshaw.dk MICHAELSEN, P. & T.W. EBERSOLE. In press. The Bradshaw rock artsystem, NW Australia -- a window into material culture, social andbelief systems of hunter-gatherers in Kimberley during the last Ice Age,Adoranten -- Journal of the Scandinavian Society for Prehistoric Art. MICHAELSEN, P., N.W. SMITH, T.W. EBERSOLE & P.P. BIRO. 2000.Australian Ice Age rock art may depict Earth's oldest recordings ofshamanistic rituals, Mankind Quarterly 41(2): 131-45. POPE, G.A. 2000. Weathering of petroglyphs: direct assessment andimplications for dating methods, ANTIQUITY 74: 833-43. ROBERTS, R., G.L. WALSH, A. MURRAY, R. OLLEY, R. JONES, M.J.MORWOOD, C. TUNIZ, E. LAWSON, M. MACPHAIL, D. BOWDERY & I. NAUMAN.1997. Luminescence luminescence,general term applied to all forms of cool light, i.e., light emitted by sources other than a hot, incandescent body, such as a black body radiator. dating of rock art and past environments usingmud-wasp nests in northern Australia, Nature 387: 173-6. STANTON, K. 1998. Rock art -- an emerging discipline, Journal ofthe West 37 (4): 31-7. WALSH, G.L. & M.J. MORWOOD. 1999. Spear and spearthrowerevolution in the Kimberley region NW Australia: evidence from rock art,Archeology in Oceania 34: 45-58. WATCHMAN, A.L., G.L. WALSH, M.J. MORWOOD & C. TUNIZ. 1997. AMS AMS - Andrew Message System radiocarbon age estimates for early rock paintings in the Kimberley, NWAustralia: preliminary results, Rock Art Research 14(1): 18-26. P.P BIRO, T.W. EBERSOLE, M.A.J. FELDER, I.B. JENSEN, P. MICHAELSEN,N.W. SMITH & T. VON LIPTAK(*) (*) Michaelsen, School of Earth Sciences, James Cook University Situated in the tropical gardens of the campus, the halls of residence provide students with modern social and sporting facilities as well as the opportunity to choose between catered or self-catered accommodation. ,Townsville QLD QLDor Qld Queensland 4811, Australia. Per. Michaelsen@jcu.edu.au