A black coating overlies rock paintings found within Little Lost Rive Cave, Idaho. A calibrated radiocarbon date of 1390-1040 B.C. was obtained by Steelman et al.1 However, this relies on the assumption that the black coating was formed by some human activity. For further characterization and to verify that the coating is anthropogenic, THM-GC-MS was performed on various samples collected throughout the cave, including soil samples from inside, outside, and above the cave. Humic and fulvic acids, synthetic and natural melanin, and experimentally created cooking residues were also analyzed as standard materials. By comparing the resulting chromatograms and the compounds identified by mass spectrometry, it was determined that the black coating is not a synthetic or natural melanin and bears little resemblance to the cooking residues. The coating bears most resemblance to humic acid standards, indicating an environmental origin
