Teotihuacan is one of the most studied archaeological sites in Mesoamerica because of its exceptional size and urban planning; however, its last years of occupation and abandonment are still under debate. We report a high-resolution chronology for the Xalla complex integrating archaeomagnetic dates, radiocarbon (14C) ages, and detailed archaeological information about sample type and context in a Bayesian model. The model includes 42 14C ages and 7 archaeomagnetic dates grouped in 6 phases, including samples from collapsed roofs with 14C ages earlier than expected, suggesting a problem of inbuilt age. The archaeomagnetic dates on lime plasters were classified in unburned samples, related to the time of construction, and burned samples, related to the Big Fire associated to the abandonment of Teotihuacan. The modeled 14C ages resulted in shorter intervals, with the possibility of differentiating the construction phases, confirming that big beams had inbuilt age. Further, combining the two dating methods and classifying lime plaster samples in burned and unburned, it was possible to date different events within the same archaeological context. It is concluded that by combining these two dating methods and understanding the moment that each sample is dating, it is possible to obtain solid and precise chronologies.

We report comprehensive rock-magnetic and archaeointensity investigations from 21 well-constrained pottery fragments from the Catamarca province of northwest Argentina. The absolute ages of the studied sites are ascertained by several high-quality radiometric ages and range between 1940 to 114014C yr BP. Magnetic mineralogy experiments indicates that the remanence is carried by thermally stable Ti-poor titanomagnetites. Forty-seven samples belonging to 11 out of 98 studied potsherds yielded reliable absolute intensity determinations judging from the quality parameters associated with the Thellier double-heating experiments. Moreover, we analyzed the available absolute geomagnetic intensities associated with the radiometric ages to construct the first intensity paleosecular variation curve (PSVC) for South America using thermoremanent magnetization carried by burned archaeological artifacts obtained in the present investigation and 79 other selected archaeointensities (out of 213 published in the literature). The dataset is used to build the PSVC reference curve by combined bootstrap and temporal P-spline methods. The variation curve shows significant differences with the global prediction model SHA.DIF.14k mainly based on the GEOMAGIA database. This intensity PSVC curve shows reasonably good agreement with paleosecular variation curves for Europe between 850 through 1150 BC and for Asia between 1000 and 1500 BC. This regional curve may be used as most reliable archaeomagnetic dating tool for the major part of South America (Peru, Brazil, Argentina, Chile, and Bolivia) for the last two millennia.

Landscape geophysical survey around the small upland ‘henge’ at Yarnbury, Grassington, North Yorkshire revealed few anthropogenic features around the enclosure but did identify a small rectangular structure in the same field. Sample trenching of this feature, radiocarbon and archaeomagnetic dating proved it to be an earlier Neolithic post and wattle structure of a type that is being increasingly recognised in Ireland and the west of Britain. It is the first to be recognised in the Yorkshire Dales and it is argued that the Dales may have been pivotal in the Neolithic for east–west trade as well as pastoral upland agriculture.