watch dating dark us online - Esr dating
The ages obtained for the four other teeth are, respectively, 624 79/−73 and 627 73/−71 ka for the lower sands and 458 39/−37 and 502 43/−41 ka for the upper sands (Fig. in terms of bio- and lithostratigraphy, as well as depth in the deposits.The two sand samples Mau 1 and Mau 2 were taken 0.5 m below and above the gravel bed.We have calculated 108 dates (10–20 per dated layer) and can minimize errors caused by incomplete reset of the luminescence clock—resulting in age overestimation—due to insufficient light exposure in the fluvial sediment environment (7, 8).
Here we show using electron spin resonance (ESR) measurements of the calcite encrustation and of bone fragments that the age of the Petralona hominid lies between 160,000 and 240,000 yr.
We also demonstrate, by trace element analysis, that the composition of the calcite encrustation is the same as that of the very top of the travertine floor.
Mammalian biostratigraphy places the find layer in a young, but not the youngest, interglacial of the Cromerian complex, probably Cromerian IV or Cromerian III (2, 4).
The faunal assemblage from the lower sands, including at Mauer matches or may be slightly less advanced than that at Isernia, indicating that Mauer should be at least as old as the Italian locality (4).
As reported in a previous study (10), most of the Mauer dental-tissue samples show evidence of postmortem uranium uptake, allowing the calculation of reliable ESR-US ages.
However, for five samples (i.e., ≈25% of the material analyzed), determination of the -parameter was not possible, and this quantity was fixed equal to −1 to allow an age calculation.
This procedure leads to an apparent systematic underestimation of the ESR-US ages in comparison with the other samples extracted from the same fluvial unit.
The results obtained should be treated as minimum ages and cannot be considered in the geochronological interpretation.
Magnetostratigraphic studies on clay layers below and within the Mauer sands show normal polarity.