Controversy has surrounded the All-American Man pictograph in southeast Utah since its discovery in the 1950s. Its coloration, similar to the flag of the United States of America, has led to questions regarding its authenticity. We have obtained two radiocarbon values on a single sample comprised of pigmented sandstone fragments from one small area of this pictograph. They suggest the pictograph dates to the fourteenth century and indicate that it is an authentic, prehistoric pictograph, probably Anasazi in origin.
Other forms of defilement have been carried out in the interest of enhancing photography. The chalked outline of the ‘All American Man’ pictograph ( Figure 2), a pictograph we recently dated , is one example of this type of Received 19 January 1993 desecration. It is hard to remove chalk without causing damage to the rock art.
Both sources are millions of years old and would yield ‘infinite’ radiocarbon ages of >40 000-50 000 years B.P. Previous experiments performed in our laboratory have shown that inorganic carbonates do not decompose in the experimental conditions used for the oxygen plasma extraction method . We have also found that calcium oxalate (CaC204), which sometimes occurs as an accretion on rock paintings and which has been identified on another pictograph sample from Utah , does not cause contamination of the organic carbon during the oxygen plasma treatment. Neither carbonates nor oxalates affect the radiocarbon age in this technique.