Lithic Technology

Prehispanic lithic tool reduction technologies throughout the Americas comprise both formal and informal techniques, each requiring different skill levels to produce the desired tool type. The presence of any combination of these technologies varies across space and time and is dependent on a number of overlapping variables, including resource availability and accessibility, material quality, and presence/absence of specialized production knowledge. Formalized tool reduction techniques require a specialized knowledge of fracture mechanics and a mental template of what the final form of the product will be, since tool production involves several steps in the lithic reduction continuum. Formalized techniques include flake-core technology that produces usable flakes and bifacial tools and core-tool technology that produces prismatic blades. Formalized bifacial technology and blades have been recovered in Ecuador from deposits dating throughout the Preceramic Period at sites like Chobshi Cave (Burger et al. 1994), El Inga (Mayer-Oakes 1986), and along the Guayas coast (Meggers 1966).

In contrast, informal reduction techniques do not require specialized knowledge on the part of the tool fabricator, since the objective is to obtain a simple cutting edge rather than a preconceived tool form. For this reason, all products of informal reduction may function as a tool, but their use as such is at the discretion of the fabricator. The advantage of this technique over formal technologies is that anyone, regardless of skill, can produce a serviceable tool. In addition, informal reduction is well suited to very small pieces of raw material or material of poor quality.

Informal techniques include bipolar reduction and expedient flake reduction. Bipolar reduction reduces small cobbles or small pieces of raw material into flakes through a bipolar fracture method whereby the core is placed on an anvil, often a flat stone, and struck at an ~90o angle with a percussor. Bipolar reduction is very often the only viable method of producing flakes from heavily decorticated river cobbles, small ovoid pebbles or from very small pieces of raw material (Flenniken 1981; Torres 1998). Often bipolar reduction is employed to maximize the amount of useable material from any given piece of raw material. As such, bipolar reduction is usually found where material is scarce, although many exceptions exist. During the Late Formative to Classic Periods on the southern Gulf Coast of Mexico, for instance, bipolar technology was used at the same time as formal reduction techniques, but for different purposes (Knight and Pool 2008).

While some bipolar debitage is indistinguishable from other reduction technologies, several distinctive bipolar artifact types exist in the Quijos Valley Project assemblage. Bipolar cores were very common in the assemblage and are often thumbnail sized pieces that have two or more battered edges, usually at opposite ends. Flake scars are visible emanating from these battered edges, sometimes extending the length of both faces, sometimes extending the full length of one face and only partially along the opposite face, and sometimes only partially along both faces. Nonetheless, the removal of flakes on both faces leaves the core lenticular in cross-section. Often a third or fourth edge also is battered indicating the core had been turned on its side to remove additional flakes. Negative bulb scarring is always very diffuse, if present at all. Often unidirectional, and sometime bidirectional ripples are present on the core faces.

The most commonly identified bipolar flake artifact is what I refer to as a “sheared flake.” The term sheared flaked is adopted from Crabtree (1982:5) in describing the shearing effect on a pebble by the radiating force caused by direct percussion in bipolar reduction. Sheared flakes are triangular in cross section and, therefore, have three faces, although two appear to be more prominent than the third. All faces of a sheared flake lack negative scarring or any evidence of the percussion force that removed them from a core; they have little to no bulbar scarring or ripple marks. The morphology of a sheared flake best fits the description Crabtree (1982:5) provides for bipolar debitage as resembling “segments of an orange.” Crushed platforms are often identifiable on opposite ends, although it is not uncommon for one end to be completely obliterated. Sheared flakes are, on average, slightly longer than bipolar cores. This, coupled with the fact that they do not exhibit any negative scarring on their faces, suggests that they are removed at an earlier stage in the bipolar reduction process than any flakes removed from bipolar cores. Many sheared flakes were used as tools as they often exhibit use wear.

Bipolar flakes comprise the third most common bipolar artifact category. These are flakes with evidence of crushing at opposite ends with a combination of shearing and/or rippling on their ventral faces. In addition evidence for bidirectional flake scarring on their dorsal faces is often present.