W.M. Childers | Search USGS

USGS1979

Temperature calibration of amino acid racemization: Age implications for the Yuha skeleton

D/L of aspartic acid ranged from 0.52 to 0.56 for femur samples of the Yuha skeleton. Subsurface temperature measurements made at the burial site indicate average annual temperature is 18°C and diagenetic temperature is 21.6°C. These data and a relation derived for the dependence of the aspartic acid rate constant on diagenetic temperature indicate an age of 23,600. The result is consistent with 14 C and 230 Th dating of calcrete found coating the bones.

Earth and Planetary Science Letters↗

USGS1976

Antiquity of man in America indicated by radiometric dates on the Yuha burial site

MUCH evidence suggests that man was present in the Western Hemisphere before 12,000 yr ago, but the case has remained less than conclusive 1 . In some situations, the geological age of the site is reasonably well established but the association or nature of the artefacts is questionable 2,3 . In other cases, museum specimens of human bones dated by radiocarbon analysis of collagen lack desirable information concerning site location, geology, and stratigraphy even though the accuracy of their absolute ages seems valid 4–6 . We report here the results of radiometric dates of the Yuha burial site from Imperial County, California, for which the geology and stratigraphy have been documented and reported in detail.

Nature↗