Between 1999 and 2001, archaeological excavations undertaken just south of the town of Delémont prior to the construction of the A16 Transjurane motorway led to the discovery of five sites dating to the metal ages: Le Tayment, La Beuchille, La Deute, Les Prés de La Communance and La Communance. All contained remains of Late Bronze Age occupations and most produced finds dating to the Late Iron Age. Two sites furnished evidence of Early Iron Age settlements.

The geology of the sites is discussed in the first section of this volume (chap. 2). After placing each site in its geomorphological context and presenting their general stratigraphy, particular problems posed by three of the five sites (Le Tayment, La Deute and Les Prés de La Communance) are examined in detail. The concluding part of this analysis consists of a discussion of the palaeoenvironment and human impact on sediment formation.

The features and the finds discovered at each site are described in the following five chapters.

The site of Le Tayment (chap. 3) is very small, not only in terms of its excavated surface, but also in the number of features and finds. Any conclusion must therefore remain doubtful. We can roughly date the first occupation to the Late Bronze Age, the second probably occurred during the early or the middle phase of the Late Iron Age. The rare features do not permit any firm conclusions about settlement type or extent, but they are probably the remains of an isolated farmstead.

La Beuchille (chap. 4) lies on a wide and in modern times intensively cultivated terrace. Agriculture seems to have obliterated the original archaeological layers and destroyed some of the features as well as thoroughly mixed the finds. The majority of the artefacts can be assigned to the first, Late Bronze Age occupation (Ha B2). Any surviving prehistoric features also appear to belong to this phase. Several finds date to the Late Iron Age, others to the roman period and document a limited or temporary occupation of the site at these times. Among the undated finds is a small assemblage of iron slag and hammerscale, the scant remains of a smithy established during the Late Iron Age or the roman period.

La Deute (chap. 5) occupies a narrow terrace in a lateral valley and revealed traces of two occupations. The older phase dates to the Late Bronze Age (Ha B1/ early B2). The original archaeological layer has been completely eroded and the buildings were probably situated just to the southwest of the excavated area. Two fragments of wire fibulae date the second phase to the Late Iron Age (La Tène C2/D1a). At this time, an isolated farmstead occupied most of the terrace. Two post-built buildings and several pits cover the northern half of the site, while the southern part revealed traces of a smithy.

Les Prés de La Communance (chap. 6) is the largest site and consists of four independent occupation zones. They were occupied respectively at the end of the Late Bronze Age (Ha B3, zone A), during the Early Iron Age (Ha C, zone D), the early phase of the Late Iron Age (zone C) and probably the middle phase of the Late Iron Age (zone B). Excepting A, every zone provided clear plans of post-built structures. They represent the remains of isolated farmsteads consisting of one to three buildings of varying function. The assemblages consist mostly of potsherds. Several fragments of pottery made with pyroxene-enriched clay were found in zone C, confirming the Early La Tène date of this particular farmstead and proof of economic ties to the Kaiserstuhl region in the Upper Rhine Valley, nearest source of pyroxene-enriched clay.

The site of La Communance (chap. 7) is best known for its roman mausoleum, but also provided finds dating to two, possibly three prehistoric periods. Most of the prehistoric pottery can be assigned to the Late Bronze Age (Ha B3) and were found in disturbed sediments displaced during the construction or the demolition of the roman mausoleum. The absence of features or in situ finds renders any further interpretation of this occupation impossible. Two complete pottery vessels found during the 1948 excavation belong to a second occupation dating to the Early Iron Age (Ha C or D1). Traces of fire and burnt bones, badly documented at the time, suggest the presence of an Early Iron Age cemetery about 300 m to the north of the roman mausoleum. A small number of potsherds found in the layers associated with the mausoleum appear to date to a late phase of the Late Iron Age, but they could also belong to vessels made in the Celtic tradition during roman times and deposited during the construction of the monument.

In the concluding section of the volume, the results obtained from the different sites are correlated and discussed in the regional context. In the Delémont Valley, little is known about prehistoric settlement before the Bronze Age. A considerable number of Late Bronze Age sites were documented in recent years and can be inserted into a chronological framework. Numerous features and finds from the Iron Age document the subsequent settlements. However, little can as yet be said about local Bronze Age architecture. The oldest house plans date to the Iron Age (Halstatt C) and usually represent single-aisled post-built structures of modest size. Standing alone or in small groups, these buildings represent the remains of isolated farmsteads. The absence of similar features from the Late Bronze Age sites of the Delémont Valley probably indicates a preference for other building techniques that do not require the use of posts, such as frame construction based on sill beams or Blockbau.

Translation: Robert Fellner