At Qillqatani, the Middle Formative comprises the bulk of Formative B layers and all of the Formative C layers (see Qillqatani data in Section X3.4.2X). In Formative B layers, Chivay obsidian is the only type represented in the four samples that were analyzed and the lithic assemblage suggests that formal tools were not being produced at the site as no evidence of obsidian tools were found in these levels. Obsidian flakes, however, persist as 18% of the lithic assemblage from that level. Subsequently, in the Formative C level that begins around 900 BCE and corresponds approximately with the latter half of the Middle Formative as well as the rise of the Yaya-Mama tradition in the south Titicaca Basin, there is a distinctive shift in the use of obsidian at Qillqatani. Whereas all prior obsidian samples from Qillqatani were Chivay after the initial Middle Archaic sample, the obsidian samples in Qillqatani Formative C levels are only 60% from the Chivay source.
The other samples come from Aconcahua, a source of lower-quality obsidian that is near the Qillqatani shelter, and from Tumuku, an as-yet undiscovered source that may be located close to the three-way border between Peru, Bolivia, and Chile, and finally Alca obsidian occurs for the first and only time at Qillqatani in these levels. Given that Alca obsidian also occurs at Pukara, Incatunahuiri (surface) and at Taraco in quantity (16% of assemblage, n = 9), the presence of Alca obsidian at Qillqatani is consistent with the abundance of Alca material in circulation in that time. A sample of Alca obsidian has also been found on the Island of the Sun (Frye, et al. 1998), though it was from a surface context.
Table 3-6Xshows that obsidian tools in Formative C levels at Qillqatani are abundant (n = 19) and relatively large on average (1.21 g), and the non-obsidian tools were also very abundant (n = 187) for this level.