First direct ¹⁴C ages on Hawaiian petroglyphs

We collected organics encapsulated by coatings of amorphous silica from 13 petroglyphs on Kaho'olawe Island, Hawai'i. Silica-glaze coatings can form within a few decades in Hawai'i. After backscatter electron microscopy of the overlying silica coating determined that it had been deposited in layers sequentially, organics were treated with NaOH, HCl, and HF, and were radiocarbon-dated at the New Zealand accelerator. The minimum ages obtained for these Kaho'olawe petroglyphs indicate that they span at least 80 percent of the time that the Hawaiian Islands have been occupied. Stick figures are the oldest petroglyphs, but they overlap with other linear motifs (fish hook, dog) as well as the triangular-bodied figures, which came later.