Obsidian Blades from La Blanca, a Changing Lithic Industry on the South Coast of Guatemala

In a study of Middle Preclassic (Conchas phase) ceramics from the site of La Blanca, Love (1989) derived a sequence of four subphases. Here, the focus is on 431 prismatic obsidian blades excavated from the same deposits in order to discern if patterns of change can be discovered in this lithic industry. For each blade, recorded attributes describe blade dimensions and edge wear, as observed through low-power microscopy. Chronological controls were set by ceramic associations. Through the sequence, blades became smaller and more fragmentary, due, we hypothesized, to an increasing scarcity of obsidian. As predicted from these trends, we found that wear patterns became more pronounced through time, and use of a bipolar technology became increasingly important for removing (rejuvenating) worn lateral edges. A definite obsidian-blade sequence emerged, which was investigated through linear discriminant-function analyses.