Optically stimulated luminescence (OSL) dating is used to determine the (robust) chronology of the phases of sediment deposition and incision in a headwater sub-basin of the Yzeron Basin, France.
Different statistical approaches to extract the mean equivalent dose from dose distributions are compared to estimate the effect of differential bleaching of the OSL signal prior to deposition.
Des datations par OSL (Optically Stimulated Luminescence) sont utilisées pour reconstituer la chronologie de phases d’aggradation et d’incision dans un sous-bassin élémentaire du bassin de l’Yzeron (France).
Différents traitements statistiques visant à extraire les doses équivalentes moyennes des distributions des doses sont comparés pour estimer l’effet de la variété du blanchiment du signal OSL antérieur au dépôt.
Goodyear, who has garnered international attention for his discoveries of tools that pre-date what is believed to be humans' arrival in North America, announced the test results, which were done by the University of California at Irvine Laboratory, Wednesday (Nov .17).
"The dates could actually be older," Goodyear says.
Age overestimation due to partial bleaching is thought to be insignificant.
The OSL ages suggest that the glacial sediments studied were deposited during MIS 12 rather than in different post MIS 12 stages.
The findings are significant because they suggest that humans inhabited North America well before the last ice age more than 20,000 years ago, a potentially explosive revelation in American archaeology.
The channel incised during this period was later partly filled with sediment.
The decline of agricultural land use from about 1915 onwards decreased sediment supply, while the increase of urbanisation from about 1950 amplified the flow energy of flooding by pluvial waters and overflows from storm basins, causing the presently ongoing incision in the area that began about AD 1975.
during the industrial revolution more carbon-12 was being produced offsetting the ratio a bit).
Carbon dating is somewhat accurate because we are able to determine what the ratio was in the unobservable past to a certain extent.