The age of the Lower Paleolithic occupation at Schöningen.

Thermoluminescence (TL) data are presented for eight samples of heated flint collected at the archaeological site of Schöningen 13/I-1 (Cycle I), for which a Holsteinian age is suggested by palynology of stratigraphically similar positions within a cyclic sedimentological model for the Quaternary sequence of Schöningen. Although the fire responsible for the zeroing of the TL-signal cannot be unequivocally attributed to human activities, any time difference between a natural fire and the human occupation is negligible for a site of this antiquity. The weighted mean age of 321 ± 16 ka places the last heating of the flints nominally in the age range of Marine Isotope Stages (MIS) 10 to 8. By inference this data would suggest an attribution of the Holsteinian to MIS 9 and may also serve as a maximum age estimate for the spear site of Schöningen 13/II-4 (Cycle II). Considering the chronometric data available and following an alternative sedimentological model the age of these two sites at Schöningen can be considered as belonging to the same climatic cycle. This suggests an attribution to MIS 9, and by inference provides an age estimate of 337-300 ka for the oldest spears in human history.

Radiometric dating of the type-site for Homo heidelbergensis at Mauer, Germany.

The Mauer mandible, holotype of Homo heidelbergensis, 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. 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 Homo heidelbergensis at Mauer to 609 ± 40 ka. This result demonstrates that the mandible is the oldest hominin fossil reported to date from central and northern Europe and raises questions concerning the phyletic relationship of Homo heidelbergensis to more ancient populations documented from southern Europe and in Africa. We address the paleoanthropological significance of the Mauer jaw in light of this dating evidence.

Feldspar flotation as a quartz-purification method in cosmogenic nuclide dating: A case study of fluvial sediments from the Pamir.

Cosmogenic nuclide (CN) dating relies on specific target minerals such as quartz as markers to identify geologic events, including the timing of landscape evolution. The presence of feldspar in sediment samples poses a challenge to the separation of quartz and affects the chemical procedures for extracting the radioactive CNs 10Be and 26Al. Additionally, feldspar contamination reduces the 26Al/27Al ratio, thus hinders the accurate determination of 26Al by accelerator mass spectrometry (AMS). Using fluvial sediment samples from Central Asia, which contain 16-50 weight percent (wt.%) of feldspar, we show that the standard physical separation and chemical cleaning-up procedures for quartz-enrichment reduces the feldspar content to only 9-47 wt.%. We present a new froth flotation mineral-separation device and procedure that allows for very effective quartz enrichment before CN chemistry. Our flotation cell, which has a volume of 600 cm3, is built of borosilicate glass, holds up to 90 g of sample, and achieves quartz and feldspar separation in ≤2 h for very feldspar-rich samples. We trace the stepwise enrichment of quartz to 95-100% purity with our procedure by X-ray diffraction analysis.