The mesolithic rock-shelter of Gripons, St. Ursanne was discovered in 1986 through archaeological prospecting along the N16-Transjura route. Three successive excavations were undertaken between 1987 and 1989. Due to the limited dimensions of the site, it was possible to use minute digging techniques, including notably the systematic sifting of all sediments to recover elusive vestiges as small as 2mm in size.

With the exception of a sterile deposit at the base of the layers, the shelter-fill is entirely Holocene. The major interest of the site is the presence of two occupation periods prior to the Neolithic, one attributed to the early Mesolithic and the other to the late Mesolithic.

The oldest archaeological horizon is also the most important, as much by the quality of its vestiges as by their quantity. The major traits of the lithic industry are: an abundance of very small microliths, a high number of scrapers and the relative discretion of the other tools' shapes, which are essentially retouched flakes and bladelets. The spectrum of microliths is clearly dominated by scalenes, but we also found some isosceles and segments as well as some points, mainly with a retouched base.

ln spite of intense fragmentation and systematic calcination, the bone vestiges attest that aurochs, deer, wild boar and beaver were hunted as well as various furry species (Mustelids). The presence of a fish vertebra leads us to believe that fishing went on in the nearby rivers. The great number of carbonized hazelnut shell fragments indicates that this fruit was systematically collected.

The spatial analysis of the different categories of vestiges indicates at least one area where flint tools were prepared and scrapers were manufactured. The microwear study of the scrapers suggests that they were then used at the site for preparing skins for tanning. All these activities went on around a central hearth.

Petrographic analysis of siliceous resources demonstrates that the group of people living in Gripons were firmly anchored to their territory, because they knew the nearby resources well. Nevertheless, they obtained silex from the Olten area because of its superior quality. This is the only indication of long-distance contacts discovered at the site.

Several Carbon-14 datings place this complex in the first half of the Boreal, that is to say between 9000 and 8500 B.P.

The late Mesolithic horizon is much less rich, as the shelter was only used for brief periods at that time. The lithic industry consists of retouched bladelets associated with trapezoid microliths; a large proportion of broken bladelets is an indication of possible microlith manufacture.

This late Mesolithic is dated to the second half of the 7th millennium B.P.

Only some isolated archaeological objects prove that the shelter was still in use during the Neolithic and the late Bronze Age as well as in historic times.

Apart from the disciplines directly related to the study of silex (petrography, microwear analysis), several specialists contributed to the analysis of the archaeologicallayers (sedimentologist, malacologist, palynologist, anthracologist). The synthesis of the results obtained in each branch allows us to reconstruct important events in the history of the shelter and to reconstitute the natural habitat in which mesolithic man evolved. Thus, during the Boreal, we witness the development of a hardwood forest (hazelnut, linden, elm) where beech and white pine begin to appear. Relics of a pine-wood remain in the immediate, surroundings of the shelter. During the early Atlantic, the rise in temperature and humidity favorized the growth of a dense forest of thermophilic hardwoods (linden, hazelnut, oak, elm, ash) where yew was already present since it is abundant in the charcoals of the shelter.

Translation: Janet Lechmann-McCallion