 | This articlemay be too technical for most readers to understand. Pleasehelp improve it tomake it understandable to non-experts, without removing the technical details.(November 2010) (Learn how and when to remove this message) |
Inarchaeology, aprismatic blade is a long, narrow, specializedstone flake tool with a sharp edge, like a small razor blade.[1] Prismatic blades are flaked fromstone cores throughpressure flaking or direct percussion.[2] This process results in a very standardized finished tool andwaste assemblage. The most famous and most prevalent prismatic blade material isobsidian, asobsidian use was widespread in Mesoamerica, thoughchert,flint, andchalcedony blades are not uncommon. The term is generally restricted toMesoamerican archaeology, although some examples are found in theOld World, for example in aMinoan grave inCrete.[3]
Prismatic blades were used for cutting and scraping, and have been reshaped into other tool types, such asprojectile points andawls.
Prismatic blades are oftentrapezoidal in cross section, but very close in appearance to anisosceles trapezoid. Triangular blades (in cross-section) are also common. The ventral surface of the prismatic blade is very smooth, sometimes bearing slight rippling reflecting the direction of applied force and a very smallbulb of applied force (indicative of pressure reduction). Flake scars are absent on the ventral surface of these blades, thougheraillure flakes are sometimes present on the bulb. The dorsal surface, on the other hand, exhibits scar ridges running parallel to the long axis of the blade. These facets are created by the previous removal of blades from the core. The proximal end contains the blade'sstriking platform and its bulb of applied force, while the distal end will consist of a snap break, a feather termination, or a stepped termination.
Obsidian prismatic blade production was ubiquitous in Mesoamerica, and these tools can be found at a large majority of Mesoamericanarchaeological sites from thePreclassic period on until thearrival of the Spanish in the early 16th century. Ethnohistoric sources recount the process of prismatic blade production. FrayMotolinia, aSpanish observer, recorded:
It is in this manner: First they get out a knife stone (obsidian core) which is black likejet and 20 cm or slightly less in length, and they make it cylindrical and as thick as the calf of the leg, and they place the stone between the feet, and with a stick apply force to the edges of the stone and, at every push they give, a little knife springs off with its edges like those of a razor.[4]
The production of prismatic blades creates not only a very standardized final product, but also a standardized waste assemblage.[5] The analysis of obsidiandebitage can reveal whether or not prismatic blade production occurred at a site and, if it had, what stages of production the process included. In other words, the types of manufacturing waste present (e.g., rejuvenation flakes and/or blades, platform rejuvenation flakes, etc.) at a site can inform archaeologists about the stage in which blades were being produced.[6]