The Châtelperronian open-air site of Aranbaltza II presents a set of very particular characteristics, such as the large number of well-preserved lithic materials in a small area and the presence of lobular accumulations that represents the 33% of different size and shape of lithic materials of the whole assemblage. Through the application of density, hotspots, and 3D-fabric analysis, in combination with sedimentological data, we discuss the factors responsible of the accumulation of these archaeological materials. The main goal of this work is inferring the formation processes from a geoarchaeological perspective and the spatial organization of this site, unraveling the high-density accumulations of this site and therefore the activities carried out. The complexity of site formation processes has not traditionally been taken into account, leading to explanatory proposals in terms of human behavior disconnected from the sedimentary context. In this work, we highlight the need to analyze site formation processes before making assumptions about human behavior. Thus, the difficulties of dismantling and interpreting high density concentrations of materials in reduced areas are addressed, as it is also observed in other Châtelperronian open-air sites, like Vieux Coutets, Les Bossats at Omersson, Canaule II, or Le Basté, which show concentrations of lithic materials that have been interpreted as waste accumulations in knapping areas, where other activities also took place. The results obtained have revealed that some materials could have suffered a short-distance displacement followed by a rapid burial that protected them and their spatial integrity, thus allowing a preservation of the main zones of accumulation of materials and therefore the type of actions performed at Aranbaltza II.