One of the biggest challenges of working at the Chivay source during the 2003 season was evaluating the evidence for the incentives that drove ancient people to excavate a quarry pit to acquire larger nodules of obsidian, and the evidence for who was responsible for the quarrying work. Presumably, the earliest visitors to the Chivay source had the first pick of the largest and most homogeneous nodules, but over the millennia the source would be relatively depleted as compared with the initial abundance during early human visitation sometime in the Early Holocene. A quarry pit [Q02-2] that was encountered in the south-east quarter of Maymeja is evidence that investing labor in excavating for obsidian was indeed worthwhile.

At some sources, for example in the upper reaches of the Alca source as described by Rademaker (2005, pers. comm.) large blocks of obsidian of variable quality are found littering the surface. At lower elevations at the Alca source, and closer to large settlements, small cavities and tunnels were excavated to retrieve obsidian (Jennings and Glascock 2002).