dAf 35
BOSTYN Françoise, LANCHON Yves
Jablines
Le Haut Château (Seine-et-Marne) : Une minière de silex au Néolithique
This volume is the first of the series "Archéologie et grands travaux" created within the DAF series to welcome the publication of large scale rescue excavations, and in part financed by developers of projects in rural or urban situations. Discovered during excavations carried out before construction work on the northern TGV line, the site of Jablines uncovered a Neolithic flint mine which became the object for the first time in France, of large scale excavation. More than 1000 features bad been located and 58 shafts completly explored. The results of these studies conducted by a pluridisplinary team are presented here in detail. Finally, the site is placed within its regional environment and compared to sites of the same type in France and the rest of Europe.
Abstract
Abstract
Between August 1989 and August 1990, a very important rescue excavation, necessitated by the construction of a new TGV railway line, was carried out on a flint mine at « Le Haut Château» near Jablines (Seine-et-Marne). This site had already been identified as a mine following a limited excavation in 1981 and thanks to aerial photography. For the first time in France a neolithic flint mine has been studied in an extensive manner, necessitating a reconsideration of the methodological approach and the excavation techniques of such sites.
Topsoil removal (approximately 500 m by 70 m) enabled the true importance of the site to be revealed: more than 1000 features, of which 766 were represented by entrances to extraction areas appeared after the mechanical removal of ploughsoil. About one hundred mine shafts, selected in relation to their situation and to their surface morphology, were initially planned to be excavated. After taking into account the technical difficulties (instability of the substrata) and the problems of security, only 58 shafts have been totally explored; the study of about 10 being carried out using an unusual excavation technique, adapted to this type of feature and the short time available : .after excavation of the entry shaft, the totality of the surrounding substrata was removed by mechanical means down to gallery level. These being excavated practically using the open-cast method.
The paleo-environmental context has been studied by geological analysis (along trench permitted the precise identification of the nature of the Marne chalk substrata and the different flint beds), malacological, palynological and anthracological (study of charcoal originating from backfilling, but equally carbonised wood coming from gallery props). The synthesis of this pluridisciplinary study has given a picture of a semi-forest or edge of forest landscape.
The study of extraction features has enabled to show a great morphological variability. One can distinguish simple extraction pits, features in the form of chambers (exploitation in one or two directions), bell-shaped features (multidirectional chambers). These first types are organised in groups of variable importance, but always spaced distinctly, in the northern part of the site. A single bed of flint bed had been exploited, but with no great intensity, these features ail having a surface diameter relatively restricted (between 1.2 m and 2 m), for a depth of 2 metres.
In the southern zone, by contrast, the morphology and the organisation of the structures are different. The access shafts were 4 to 7 metres in depth and 2.50 metres or more in diameter. They were cut through a first bed of flint, exploited in a secondary manner or neglected: the lower bed being exploited by a system of radiating gallerys, communicating most of the time between themselves and those of neighbouring shafts by small creeps. The shafts were organised following a very regular pattern which cris-crossed the landscape, the underground exploitation of flint being maximal. The study of backfill has shown that, the gallerys had not been dug simultaneously, the most recent waste being used to back-fill disused gallerys. Stratigraphical sections of access shafts indicates that phases of deliberate backfilling alternated with natural erosion (by collapse of sides and over hangs).
In the central area of the zone stripped, features related to extraction had been reopened after their backfilling but only 01:)their limits. This reuse of exploitation could indicate either frequentation by another group, or the temporary abandon of extraction.
The recording .in three dimensions of extraction features has permitted not only to visualise the importance and intensity of flint extraction, but equally to quantify the volume of each structure, and to estimate its profitability.
Spacial analysis of mine shaft distribution and the extension of underground exploitation indicates an organisation of extraction completely different to that between the northern and southern zones. It probably indicates the presence of two distinct systems of flint exploitation each of different intensity, satisfying different needs. This duality is perfectly illustrated by the tracing of Tiessen polygones.
The excavation of structures and the extraction of flint blocks had been carried . out with the aid of specialised antler tools: detailed analysis of wear has enabled a classification according to types and function of antler tools. Traces of tools left on gallery walls has enabled the reconstruction of block extraction techniques and suggests the possible use of wooden tools. No traditional extraction tools. of flint had been identified. Amongst the antler tools, several rare sherds and bone remains were found, otherwise the artifacts are composed almost exclusively of flint waste and fragments of unusuable flint blocks. A large amount of raw material had been worked in situ, evidenced by several working zones, and the thousands of waste flakes and rough-outs located in the back-fill of shafts. The study of waste material was carried out by diacritic schema analysis on worked products and reconstruction, which has enabled to understand ail the phases of the operating chain of their production by individualising the principal stages. It has shown that there existed on the site a production in larges series of two distinct axe modules. The large and part of the small size axes must have been exported. It is probable that certain axes, even some more common tools (scrapers, etc.) had served during extraction (working and reworking of wood and antler tools).
A clear series of 17 carbon 14 measures permit to date this mining area of the middle neolithic Il, to around 3000 BC (uncorrected). The presence of earlier sherds (Cemy culture) in a secondary in the back-fill of mine shafts, could indicate the existence of an early phase of mining, outside the area studied.
The mine is not isolated in the region, it is part of mining complex comprising a dozen identical sites (today identified) having probably exploited different beds of tertiary flint. The study of the distribution of Jablines products, which has not been possible in this present work, must necessarily be part of a vast study these different beds and their exploitation.
