At many sites throughout the world rock art paintings have been covered by naturally deposited calcite laminations, which we demonstrate can be individually dated by recently improved uranium-series methods. Here we report the application of multi-collector inductively coupled plasma mass spectrometry to measure the ages for carbonate coatings that bracket red pigment at Lene Hara cave, East Timor, which could be evidence of human painting. These analyses establish the feasibility of dating milligram samples of finely layered calcite deposits associated with archaeological evidence of human occupation. In addition to confirming an age of less then 6300 years for the visible red paintings on the carbonate surface we also report a substantially older age of 24,000 to 29,300 years for a similar, older red pigment lamination providing possible evidence for an earlier painting episode.

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Mineralogical and geochemical variations in ten rock surface crusts are described from a large rock shelter known as Carpenter's Gap 1 in the southern Kimberley, formed at the junction between a sandstone floor and an overlying limestone roof. The finely laminated crusts, containing quartz, clays, oxalate and phosphate minerals, and sulfate salts (bassanite, gypsum, epsomite), formed over quartz-rich sandstones. Mineralogical analyses of crusts, determined by X-ray diffraction, and major element geochemical trends, in the form of element maps of cross sections, show a complex distribution of hemi-, mono-, and dihydrated sulfate and oxalate minerals vertically and laterally within the shelter. These mineralogical changes have occurred under fluctuating moisture and temperature regimes, which follow a general drying trend spatially with distance from the back wall and temporally over a period of about 20,000 years. Documenting these mineralogical changes is a first step in understanding the nature of microclimatic controls on the formation of rock surface coatings in shelters and their implications for palaeoenvironmental reconstructions and for dating engravings covered by these crusts. ᭧