Les puits de l’âge du Bronze du Parc d’Activités du Pays d’Erstein (Bas-Rhin, Alsace) : des analyses dendroarchéologiques à l’ étude de l’occupation du sol

Abstract

Between 2006 and 2014, several preventive archaeological surveys of an area of 55 ha were carried out before the development of the Parc d’Activités du Pays d’Erstein. The excavations brought to light more than three hundred, mainly domestic, features (e. g. pits, silos, storage vessels, large pits associated with wells) dating to the Bronze Age. The excavation also revealed periods of human activity during the Late Neolithic/ Early Bronze Age (Late Beaker Culture/ Bz A1) transition, the Middle Bronze Age (Bz A2-B1 then Bz C) and the Late Bronze Age (Bz D and Ha A2-B1). One of the particularities of the site is the excellent preservation of wood in the waterlogged conditions of the wells. These included eight linings, built from logs or hollowed tree trunks. Construction pits used to dig the wells contained three types of well linings that reached the ground water level : tube linings using hollowed out trunk sections, vertically planted planks and chest-like well linings using timber logs. The latter construction types were found in the same pit. Three linings consisted of hollow trunks probably using old trees. The chest-like linings used logs cut in half, whole logs or planks. The planks were split out of trunks in a radial or tangential direction. Only one lining used vertically planted planks (slabs). The exceptionally well-preserved timbers allowed sampling and analyses of 465 waterlogged wooden finds. In total 411 wood samples were anatomically identified including eight species. Oak (Quercus sp.) dominated the species assemblage, followed by maple (Acer sp.), hazel (Corylus sp.) and beech (Fagus sp.). For the purpose of dendrochronological dating only oak timbers with more than 20 tree rings were analysed and it was possible to date 113 timbers. In 48 samples the outermost ring beneath the bark (waney edge) was preserved, allowing the determination of the felling year of the used trees. Moreover, the cross dating of the 113 tree-ring width series enabled the development of three site chronologies, which could be absolutely dated based on high visual and statistical agreement with different regional oak master chronologies. The first chronology includes 12 series and covers the period 2354– 2215 BC, the second is based on 40 series covering the period 2131– 1571 BC, and the third with 62 series could be synchronised between 1320 and 1002 BC. The use period of the wells varies considerably from only a few years to several decades and in the case of wells that are regularly reused the period of use could be considerably longer. For some of the wells it has been possible to estimate the minimum duration of use and in many cases, these long-lived structures were used for several generations. Owing to the high quantity and quality of dendrochronological data, the archaeological site of the the Parc d’Activités du Pays d’Erstein offers new insights into settlement dynamics and occupation periods with an unusually precise chronological resolution for a land based site. The first occupation phase with about twenty structures located in the north and in the middle of the excavated area dates back to the Late Neolithic/ Early Bronze Age. The well dating to this first phase contains timbers dating to 2231 and 2215 BC. After a hiatus of several centuries, a second settlement phase dates to between 1750 and 1715 BC, documented by only a few oak planks from the bottom of a well. A later settlement phase dating to between the end of the 17th century and first half of the 16th century BC is located to the north of the site where two wells were dug around 1615 BC. The few features of this phase can be attributed to Middle Bronze B1. For the following phase of the Middle Bronze Age C2 only a few features were found and excavated, but no wells are dated to this phase. The settlement dating to the second half of the 13th century and the first half of the 12th century BC has several poles. Three wooden well linings date to between 1241 and 1208 BC and one earlier well was restored during this period (1237 BC). About ten features were excavated from this 75 years long phase of the Late Bronze Age. The last phase covers the 11th century and the first half of the 10th century BC with features found all over the excavation area. Four wells date to this phase covering an 80-year period from 1078 to 1002 BC and were probably in use from the last quarter of the 11th century up until the first half of the 11th century BC. The 70 or so domestic features dating to the middle of the Late Bronze Age indicate a densely occupied settlement. During the Bronze Age, the presence of small mobile settlements or homesteads that regularly moved and relocated within their territory, characterises stable land use patterns. This system seems, as the example of the Parc d’Activités du Pays d’Erstein shows, to be in place probably from the Early Bronze Age and maintained until the Late Bronze Age.