Terminal Archaic projectile points in the Ilave valley demonstrate the dramatic shift in the frequency and use of obsidian that occurred in this time period (SectionX3.4.4X). XRF analysis of 68 obsidian artifacts excavated from Jiskairumoko show that the Chivay source was used with particular intensity in this period. The XRF study found that 97% of obsidian bifaces from Terminal Archaic and Early Formative levels at Jiskairumoko were from the Chivay source, however published obsidian studies from all time periods show that typically 90% of all obsidian analyzed from Titicaca Basin sites are from the Chivay source (XTable 3-3X).