The earliest obsidian identified in the south-central Andes comes from one of the oldest confirmed sites in South America, the Paleo-Indian site of Quebrada Jaguay 280 near the coast north of Camaná, Arequipa. Sandweiss et al.(1998)report that Alca type obsidian was the dominant lithic material at the site in the Terminal Pleistocene and Early Holocene phases that were identified. Twenty-six Alca type obsidian flakes came from the older occupation that occurred during the Terminal Pleistocene and the context is dated by twelve¹⁴C dates on charcoal falling between 11,105±260 bp (BGS-1942; 11,700-10,400 BCE) and 9850±170 bp (BGS-1956; 10,100-8700 BCE). A later occupation contained one flake of Alca obsidian and it belonged to the Early Holocene II phase dated by four¹⁴C samples falling between 8053±115 (BGS-1944; 7350-6650 BCE) and 7500±130 (BGS-1700; 6600-6050 BCE). Three other obsidian flakes from the Alca source were collected but they could not be assigned to a temporal context.

Sandweiss et al. observe that the Chivay source is "less than 20 km further; the absence of Chivay obsidian at QJ-280 may indicate that this source was covered by glacial readvance during the Younger Dryas (circa 11,000 to 10,000¹⁴C yr B.P.)"(Sandweiss, et al. 1998: 1832). The Maymeja volcanic depression of the Chivay obsidian source indeed shows notable evidence of recent glaciation, but obsidian matching the "Chivay Type" is also found in smaller nodules on adjacent slopes outside the Maymeja zone as well as in the streambed below Maymeja having eroded through alluvial erosion (see Section4.5.1for maps and a discussion of the Chivay obsidian source geography). Procurement of obsidian from Chivay did not necessarily require entering the Maymeja area, however better source material can be obtained from the within the area.

Regional scale GIS analyses show Quebrada Jaguay to be 154 linear km from the Alca source, or 35.7 hours by the hiking function. In contrast, the trip to Quebrada Jaguay from the Chivay source is 170 linear km and 41.5 hours by the hiking function. Despite this relatively difference in distance, no Chivay obsidian was found at Quebrada Jaguay. It is worth noting that, despite this early find of Alca obsidian on coast, both the Alca and the Chivayobsidian types were predominantly found at high altitude throughout prehistory based on current evidence from obsidian sourcing studies. In the bigger picture, the coastal Quebrada Jaguay paleoindian finds are anomalous for Alca distributions. The next lowest altitude context for Alca to date is at the site of Omo in Moquegua, a Tiwanaku colony site at 1250 masl dating to the Middle Horizon.

Recent work by Kurt Rademaker and colleagues at the Alca source has shown that bedrock outcrops of obsidian are found as high as 4800 masl, and there are large pieces found at 3,800 masl that appear to have been transported downslope by glacial action and colluviation (K. Rademaker 2005, pers. comm.). Deposits of Alca obsidian at much lower elevations have been reported that are probably the result of pyroclastic flows(Burger, et al. 1998;Jennings and Glascock 2002). These deposits found close to the floor of the Cotahuasi valley at 2500 masl were probably available throughout the Younger Dryas and perhaps further sub-sourcing of Alca obsidian will better answer the question of which Alca deposits were being consumed during the Terminal Pleistocene by the occupants of Quebrada Jaguay.