Which of the following is not a chronometric dating method
Given the associated mammal fauna and the geological context, the find layer has been placed in the early Middle Pleistocene, but confirmatory chronometric evidence has hitherto been missing.
Here we show that two independent techniques, the combined electron spin resonance/U-series method used with mammal teeth and infrared radiofluorescence applied to sand grains, date the type-site of at Mauer to 609 ± 40 ka.
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).
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.
The Mauer sands are overlain by several Middle and Late Pleistocene glacial loess layers with interstratified interglacial paleosoil horizons, which constrain the age of the fossil to older than 350 ka (3).A juvenile partial cranium, a young adult hemimandible, teeth, and other bones have been reported from the TD6 level at Gran Dolina, antedating the Brunhes-Matuyama magnetic reversal at 780 ka (20, 21).Additionally, a lower jaw fragment has been recovered from the TE9 level at Sima del Elefante (22)., was found in 1907 in fluvial sands deposited by the Neckar River 10 km southeast of Heidelberg, Germany.The fossil is an important key to understanding early human occupation of Europe north of the Alps.