The Late Archaic in the south-central Andes signals the beginning of economic changes in the lead-up to food production, and furthermore the first signs of incipient social and political differentiation are evident in a few archaeological contexts. Some of the obsidian samples reported by Burger et al(2000: 275-288)with possible Late Archaic affiliations are from surface contexts at multicomponent sites and it is therefore difficult to confidently assign these samples to any particular period of the Archaic.
Evidence of Late Archaic obsidian use comes from excavations at the previously discussed sites of Asana, Qillqatani, and Sumbay. Several obsidian samples in the Burger et al. (2000) study were of portions of diagnostic projectile points that resemble types in Klink and Aldenderfer's (2005) point chronology. From illustrations and text(Burger, et al. 2000: 279, 281)the Qaqachupa sample appears to belong to the Late Archaic. Burger et al. describe this point as resembling a Type 7 point from Toquepala in Ravines'(1973)classification, and Klink and Aldenderfer(2005: 44)mention that their Type 4D point strongly resembles the Toquepala Type 7, making it diagnostic to the Late Archaic.
In excavated data from Asana, in Moquegua, one sample of Chivay obsidian was found in a Muruq'uta phase occupation in Level XIV-West lying above a palimpsest dated to 6040±90 (Beta-24634; 5210-4766 BCE) (Aldenderfer 1998: 269), as shown above in SectionX3.4.1X. This level lies on the Middle Archaic / Late Archaic transition. Interestingly, Chivay obsidian disappears at Asana subsequent to this time period. Furthermore, evidence of lower raw material diversity in the Late Archaic lithic assemblage point to greater geographical circumscription.
Chivay obsidian at Qillqatani is first found in the Late Archaic level WXXX dated to 5620±120 (Beta-43927; 4800-4200 BCE). The Chivay material is the second oldest obsidian fragment identified from Qillqatani (SectionX3.4.2X), the oldest obsidian is from an as-yet unknown source. Notably, the assemblages from the Qillqatani excavations do not begin to contain obsidian from the Chivay source until considerably later date than did the excavations from Asana.XFigure 3-7Xreveals that both obsidian tools and debris increase as a percentage of the assemblage in the Late Archaic. The counts of obsidian, however, are still relatively low.
Qillqatani is slightly further away than Asana than from the Chivay source, and it is at a higher altitude and further to the east. It has been suggested that perhaps the obsidian was transported via a coastal route at this early date (Frye, et al. 1998). As mentioned, Alca obsidian was also found on the coast in the Terminal Pleistocene levels although, like Chivay, Alca obsidian distributions conform over the long term to a highlands orientation. As no Chivay obsidian as ever been found below the 1250 masl (at Omo), and all Archaic Period Chivay obsidian is found above 3000 masl, the littoral route between Chivay and Asana seems improbable.
Craig and Aldenderfer(In Press)report that two obsidian projectile points from the Ilave valley in a type 3f form, diagnostic to the Late - Terminal Archaic were analyzed in 2005 with a portable XRF unit and were found to be of the Chivay type.
At Sumbay SU-3,three obsidian samples were analyzed from excavated contexts and all three turned out to be of the Chivay type(Burger, et al. 1998: 209;Burger, et al. 2000: 278), as shown in SectionX3.4.3X. Two14C dates were run and returned dates from the early part of the Late Archaic(Ravines 1982: 180-181). One sample was from stratum 3 and it was dated to 6160±120 (BONN-1558; 5400-4750 BCE). Another sample was from above it in stratum 2 and it dated to 5350±90 (BONN-1559; 4350-3980 BCE). One of the three obsidian samples came from Stratum 4 of unit 5, while the other two samples came from higher levels. The Stratum 4 sample probably dates to the Middle Archaic.
Obsidian from securely dated Late Archaic contexts show something of a reduction in regional distribution and a greater focus on locally available lithic material, suggesting a reduction in mobility or exchange in the Late Archaic. Similarly, projectile point styles became increasingly more limited in spatial distribution, with greater local variability during the Late Archaic implying reduced mobility(Klink and Aldenderfer 2005: 53). This is consistent with Aldenderfer's(1998: 260-261)observations about reduced mobility during the Late Archaic Qhuna Phase occupation at Asana when the occupants ceased to use non-local lithic raw materials. During this phase, Aldenderfer also describes increasingly formalized use of space at Asana, evidence of a ceremonial complex, and greater investment in seed grinding. In short, during this time a circumscribed population with reduced mobility was probably living in higher densities and exhibiting signs of ceremonial activity that are consistent with the scalar stress model for the emergence of leadership(Johnson 1982).
It is also worth considering the impact that scarcity may have on valuation. The lack of discarded obsidian signifies that it was not being knapped or resharpened and it was probably not abundant, but that does not mean that obsidian was not known in the larger consumption zone during this period. In the subsequent time period, the Terminal Archaic, obsidian becomes abundant on a regional scale at the same time as a host of other social and economic changes were occurring. This period, and the previously discussed Middle Archaic, correspond with what was referred to as the silencio arqueologico(Núñez and Santoro 1988)due to a dearth of archaeological data observed by investigators working in Northern Chile. The reduced evidence of circulation of obsidian from Chivay appears to correlate with a reduction in archaeological evidence regionally.
Thereis strong representation of Chivay obsidian in Arequipa at Sumbay, and it is likely that Late Archaic projectile point forms are found in the North Titicaca Basin as reported by Burger et al. (2000). However, at Asana there is little obsidian from the Colca. Possibly these reduced distributions of obsidian reflect the reduced mobility and more complex architectural investment in Late Archaic contexts at Asana(Aldenderfer 1998), and prior to the development of extensive, long distance exchange that were potentially initiated by early caravan networks during the Terminal Archaic.These conclusions, however, on not based on particularly robust data, as the sample of sites for this time period is relatively small.