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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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Current-year, 1-year-old, and 2-year-old needles were collected separately on 37 black spruce (Picea mariana Mill. B.S.P.) trees located on a heavy metal contamination gradient around the smelter in Murdochville, Québec (Canada). Needles were analyzed separately by year for the concentrations of Pb and Cu, a nonessential and an essential metal, respectively. Lead concentrations increased significantly with needle age in the highly contaminated area near the smelter. In contrast, Cu concentrations decreased with needle age in the same area. Our results support the hypothesis that the passive sequestration of toxic metals in the senescing foliage is a detoxification process contrasting with the active translocation of essential metals in the nonsenescent part of the foliage.