The role of climate, marine influence and sedimentation rates in late-Holocene estuarine evolution (SW Portugal)

Estuaries are sensitive to changes in global to regional sea level, to climate-driven variation in rainfall and to fluvial discharge. In this study, we use source and environmentally sensitive proxies together with radiocarbon dating to examine a 7-m-thick sedimentary record from the Sado estuary accumulated throughout the last 3.6 kyr. The lithofacies, geochemistry and diatom assemblages in the sediments accumulated between 3570 and 3240 cal. BP indicate a mixture between terrestrial and marine sources. The relative contribution of each source varied through time as sedimentation progressed in a low intertidal to high subtidal and low-energy accreting tidal flat. The sedimentation proceeded under a general pattern of drier and higher aridity conditions, punctuated by century-long changes of the rainfall regime that mirror an increase in storminess that affected SW Portugal and Europe. The sediment sequence contains evidence of two periods characterized by downstream displacement of the estuarine/freshwater transitional boundary, dated to 3570-3400 cal. BP and 3300-3240 cal. BP. These are intercalated by one episode where marine influence shifted upstream. All sedimentation episodes developed under high terrestrial sediment delivery to this transitional region, leading to exceptionally high sedimentation rates, independently of the relative expression of terrestrial/marine influences in sediment facies. Our data show that these disturbances are mainly climate-driven and related to variations in rainfall and only secondarily with regional sea-level oscillations. From 3240 cal. BP onwards, an abrupt change in sediment facies is noted, in which the silting estuarine bottom reaches mean sea level and continued accreting until present under prevailing freshwater conditions, the tidal flat changing to an alluvial plain. The environmental modification is accompanied by a pronounced change in sedimentation rate that decreased by two orders of magnitude, reflecting the loss of accommodation space rather than the influence of climate or regional sea-level drivers.FCT by Spanish Ministry of Science and Innovation [SFRH/BD/110270/2015, HAR2014-51830-P, HAR2011-29907-C03-00]FCTPortuguese Foundation for Science and Technology [PTDC/HISARQ/121592/2010]Instituto Dom Luiz-IDL [UID/GEO/50019/2013]info:eu-repo/semantics/publishedVersio

Mesolithic skull cults?

While long known as a feature of the Near Eastern Neolithic, there is growing evidence for the special treatment of the human head in Mesolithic Europe. This takes the form of secondary deposition of crania and mandibles, often in unusual contexts, including as ‘grave goods’ with other burials; cutmarks suggesting decapitation, scalping and defleshing; and the deposition of fleshed heads in pits, as well as, most recently, on stakes in shallow pools. After reviewing this evidence, discussion turns to its interpretation. Possible links with the ‘ancestors’ are explored, and ethnographic support for their importance among hunter-gatherers is reviewed. If accepted, there may be implications for the expression of territoriality in the Mesolithic. The blurring of the lines between revered ancestor and enemy when interpreting the treatment of human heads is emphasised

Long-term dietary change in Atlantic and Mediterranean Iberia with the introduction of agriculture : a stable isotope perspective

The Neolithic expansion in the Iberian Peninsula is marked by the introduction of livestock and domesticated crops which modified subsistence strategies in an unprecedented manner. Bulk collagen stable carbon and nitrogen isotope analysis has been essential to track these changes, which have largely been discussed in relation to particular geographic areas or single case studies. This paper reviews the available isotope literature to provide a regional, long-term synthesis of dietary changes associated with the expansion of the Neolithic and the establishment of farming economy in the Iberian Peninsula. Bulk collagen stable carbon and nitrogen isotope values of 763 human individuals and 283 faunal remains from the Mesolithic to the Late Neolithic period in Iberia (ca. 8000–3000 cal BC) were collated and analysed using a Bayesian mixing model. The results show that Mesolithic diets were isotopically diverse in both the Atlantic and Mediterranean regions of the Iberian Peninsula, and that a significant decrease in variability happened with the Neolithisation, culminating with the establishment of farming economies and reliance on terrestrial resources in the Late Neolithic