The first of these was a marked excavator bias in favor of the recovery of scrapers, especially the more heavily-worked examples.

This was shown by analyzing a sample of material recovered from Ami's backdirt that had eroded into the trench. This backdirt was exceptionally rich in artifactual material, but the bulk of it consisted of notches and denticulates, along with some lightly-retouched scrapers. The two series -- one from the museum collections representing the former excavation and one from the backdirt -- completely and unmistakenly bracketed the range of tools uncovered in the current excavation. Since the museum collections contained mostly scrapers, it is understandable that those industries would be assigned to Charentian assemblage groups.