1. Survey Objectives and Regional Geomorphology
During the winter and early spring months of 2026, CAPRA mobilized a multidisciplinary volunteer survey group to investigate the Pleistocene alluvial terraces situated at the confluence of the Drôme and Rhône rivers, between Livron-sur-Drôme, Étoile-sur-Rhône, and Beauvallon. This geographical zone represents a vital crossroads of ancient human mobility: a wide migratory funnel connecting the Mediterranean coastal plain with the inner valleys of the Alpine arc.
The primary scientific objective of the 2026 campaign was to assess the impact of recent agricultural plowing, soil erosion, and climate-induced flash floods on previously unmapped Middle and Upper Paleolithic archaeological horizons. By combining systematic line-walking pedestrian surveys with non-destructive manual sediment coring, our team sought to delimit the spatial extent of buried stone tool scatters and evaluate their stratigraphic integrity.
2. Survey Methodology and Field Protocol
Fieldwork was conducted across twelve discrete agricultural parcel sectors covering a cumulative surface area of 48 hectares. The timing was scheduled following winter frost cycles and subsequent gentle rain events, which naturally washed surface soil crumbs and enhanced artifact visibility:
- Line-Walking Traverses: Teams of four to six volunteers spaced at regular 10-meter intervals traversed each agricultural field in parallel lines. Every observed lithic piece exhibiting human knapping characteristics was marked with a high-visibility survey pin.
- Sub-Metric Spatial Recording: A designated surveyor equipped with a high-precision differential GNSS receiver recorded the exact coordinates and elevation of each pin before collection.
- Sediment Augering: Where surface flint densities exceeded five artifacts per square meter, manual Dutch auger corings (diameter 70 mm) were advanced to depths between 1.2 and 1.8 meters to determine whether the surface artifacts derived from deeply buried intact paleosols or represented displaced colluvial deposits.
3. Major Discoveries and Technological Analysis
The 2026 campaign resulted in the identification and collection of 412 diagnostic prehistoric lithic artifacts, categorized into two dominant chronological horizons:
- Middle Paleolithic Mousterian Horizon (Sector B-4, "Les Grands Quartiers"): This sector yielded a remarkable assemblage of 287 flint artifacts exhibiting classical Levallois recurrent centripetal reduction strategies. Notable finds include three broad Levallois points, sixteen convex side scrapers (racloirs simples convexes) with scalariform retouch, and multiple discoidal cores fashioned from local fluvial quartzite and silicified limestone river cobbles. The technological characteristics suggest repeated seasonal butchery and wood-scraping episodes by Neanderthal hunter groups tracking ungulate herds across the paleo-floodplain.
- Late Upper Paleolithic Blade Assemblage (Sector F-2, "Les Vignes Basses"): Located on a slightly elevated gravel knoll overlooking a paleochannel, this sector yielded 125 artifacts characterized by laminar debitage, including fine prismatic bladelet cores, endscrapers on blade blanks (grattoirs sur bout de lame), and straight-backed bladelets. Petrographic inspection under magnification revealed that several blades were crafted from exotic Vassieux-en-Vercors bedded flint, demonstrating long-distance transport of premium raw materials across forty kilometers of rugged terrain.
4. Conservation Assessment & Recommendations for Heritage Authorities
The sediment corings carried out in Sector B-4 revealed an undisturbed, organically rich silt-clay paleosol buried at a depth of 65 centimeters beneath the modern plow layer. This confirms that beneath the disturbed agricultural surface lies an intact, sealed Paleolithic living horizon with exceptional preservation potential.
However, observed sheet erosion triggered by recent torrential rainfall has begun scouring the protective overburden. CAPRA has submitted an urgent technical advisory to the Regional Service of Archaeology (DRAC Auvergne-Rhône-Alpes) recommending:
- The formal integration of Sector B-4 into the regional archaeological sensitivity perimeter (Zone de Présomption de Prescription Archéologique).
- Collaborative outreach with the local agricultural landowner to implement low-depth tillage or perennial grass cover to prevent further soil loss.
- Targeted non-destructive electrical resistivity imaging (ERT) in autumn 2026 to map the subsurface morphology of the paleochannel without ground disturbance.
All collected artifacts have been cleaned, cataloged, and deposited in the CAPRA archival repository at Espace L'Île Girodet, where they are accessible to visiting researchers and students.