ORCID Profile
0000-0003-4061-3066
Current Organisation
Wageningen University
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Publisher: Elsevier BV
Date: 12-2000
Publisher: Geological Society of America
Date: 11-2011
DOI: 10.1130/G32244.1
Publisher: Elsevier BV
Date: 05-2009
Publisher: Copernicus GmbH
Date: 16-01-2015
Abstract: Abstract. The optically stimulated luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could potentially provide insights into sediment transport processes. However, comparison of bleaching between s les is complicated by s le-to-s le variation in aliquot size and luminescence sensitivity. Here we begin development of an age model to account for these effects. With measurement data from multi-grain aliquots, we use Bayesian computational statistics to estimate the burial dose and bleaching parameters of the single-grain dose distribution. We apply the model to 46 s les taken from fluvial sediment of Rhine branches in the Netherlands, and compare the results with environmental predictor variables (depositional environment, texture, s le depth, depth relative to mean water level, dose rate). Although obvious correlations with predictor variables are absent, there is some suggestion that the best-bleached s les are found close to the modern mean water level, and that the extent of bleaching has changed over the recent past. We hypothesise that sediment deposited near the transition of channel to overbank deposits receives the most sunlight exposure, due to local reworking after deposition. However, nearly all s les are inferred to have at least some well-bleached grains, suggesting that bleaching also occurs during fluvial transport.
Publisher: Springer Science and Business Media LLC
Date: 04-2002
Publisher: Elsevier BV
Date: 11-2013
Publisher: Elsevier BV
Date: 04-2010
Publisher: Elsevier BV
Date: 12-2010
Publisher: Springer Science and Business Media LLC
Date: 03-12-2014
DOI: 10.1038/NATURE13962
Abstract: The manufacture of geometric engravings is generally interpreted as indicative of modern cognition and behaviour. Key questions in the debate on the origin of such behaviour are whether this innovation is restricted to Homo sapiens, and whether it has a uniquely African origin. Here we report on a fossil freshwater shell assemblage from the Hauptknochenschicht ('main bone layer') of Trinil (Java, Indonesia), the type locality of Homo erectus discovered by Eugène Dubois in 1891 (refs 2 and 3). In the Dubois collection (in the Naturalis museum, Leiden, The Netherlands) we found evidence for freshwater shellfish consumption by hominins, one unambiguous shell tool, and a shell with a geometric engraving. We dated sediment contained in the shells with (40)Ar/(39)Ar and luminescence dating methods, obtaining a maximum age of 0.54 ± 0.10 million years and a minimum age of 0.43 ± 0.05 million years. This implies that the Trinil Hauptknochenschicht is younger than previously estimated. Together, our data indicate that the engraving was made by Homo erectus, and that it is considerably older than the oldest geometric engravings described so far. Although it is at present not possible to assess the function or meaning of the engraved shell, this discovery suggests that engraving abstract patterns was in the realm of Asian Homo erectus cognition and neuromotor control.
Publisher: Walter de Gruyter GmbH
Date: 22-09-2011
DOI: 10.2478/S13386-011-0048-Z
Abstract: In the OSL dating of sediment, the scatter in equivalent dose (D e) between grains is almost always larger than would be expected due to counting statistics alone. Some scatter may be caused by insufficient (partial) bleaching of some of the grains prior to deposition. In order to date partially bleached sediment, it is essential to estimate the amount of scatter caused by other processes (e.g. grain-to-grain variability in the natural dose rate). Measurements of such scatter are performed at the single-grain level by contrast, most OSL dating is performed on multi-grain subs les, for which grain-to-grain scatter is reduced through averaging. Here we provide a model for estimating the expected scatter (i.e. excluding that caused by partial bleaching) for multi-grain aliquots. The model requires as input the single-grain sensitivity distribution, the number of grains in the sub-s les, and the expected scatter at the single-grain level, all of which can be estimated to an adequate degree. The model compares well with measured values of scatter in D e, determined using aliquots of various sizes, and can be used to help produce a minimum-age D e from multi-grain subs les that is consistent with single-grain data.
Publisher: Elsevier BV
Date: 12-2000
Publisher: Elsevier BV
Date: 10-2012
No related grants have been discovered for Jakob Wallinga.