Coudoulous I is an ancient cave about fifteen meters in diameter, whose ceiling collapsed during the Middle Pleistocene, transforming it into a cave-aven open to the external environment. Large sedimentary deposits, about ten meters powerful, make it possible to reconstruct the complex history of its filling:

• the oldest levels are characteristic of an internal karst functioning and include clays surmounted by stalagmitic floors (OIS 7 or 9?);
• Lower ensemble: a chaos of large blocks and slabs, accompanied by the first faunal remains and some lithic remains, reflects the collapse of the ceiling and the opening of the cavity;
• Medium set: the cavity is filled by accumulation of elements detached from the walls (small angular blocks) or from the plateau (earth and pebbles), until forming a cone that will gradually clog the aven. This ensemble is affected by various reshuffling phenomena (solifluxion, racking) linked in particular to particularly severe climatic episodes (ice ages) (OIS 6).
• Upper set: a return to milder climatic conditions resulted in the formation of a small stalagmitic floor at the top of the sequence (OIS 5), surmounted by fine deposits, aeolian and from solifluxions marking a return of cold (OIS 4 to 2), then by the current soil.

The first anthropogenic indices (lower set) are made up of a few cut pebbles and some chips of local materials from the alluvial formations of the Lot (quartz, quartzite, basalt). They are interpreted as clues of frequentation of the cavity to acquire meat resources from large mammals accidentally fallen into the aven (active scavenger). The cavity is then also frequented by Carnivores (wolf, cuon, lynx, bear). Herbivores present include Deer, Goats, Large Bovids, Equids and ancient elephant remains and rare rhino elements.

The main level of anthropogenic occupation is layer 4 (age between 130 and 200,000 years), within the average ensemble. It associates an abundant lithic industry with numerous bison remains, corresponding to at least more than 200 individuals. The industry is mainly made on quartz and quartzite but also includes some flint parts. The latter was cut according to the Levallois method and made it possible to produce retouched tools characteristic of Mousterian. Quartz and quartzite were cut using a unifacial discoid method or by anvil cutting to produce fragments most often used raw. This set is interpreted as the result of the use of the aven as a natural trap to which the bison herds would have been directed. It is one of the strongest evidence of the existence of specialized sites used in seasonal collective hunts organized by Neanderthals, taking advantage of the topographical and morphological characteristics of a site.