Lithic flake
In
Production
Flakes may be produced by a variety of means. Force may be introduced by direct percussion (striking the core with a percussor such as a rock or antler), indirect percussion (striking the core with an object, sometimes referred to as a "punch", which itself is struck by a percussor, similar to the use of a hammer and chisel to shape stone), or by pressure. Additionally, flakes may be initiated in a
The end which received the blow or pressure is referred to as the proximal end of the flake; the terminal end is referred to as the distal end. The side displaying the bulb of force but without flake scars (barring an errailure flake scar or additional working of the flake) is called the ventral (or interior) surface, while the opposite side, displaying the flake scars of previous removals, or the cortical or original rock surface, is the dorsal (or exterior) surface.
On most natural cobbles or nodules of source material, a weathered outer rind called a cortex covers the unweathered inner material. Flakes are often differentiated by the amount of cortex present on their dorsal surfaces, because the amount of cortex indicates when in the sequence of reduction the flake came from. Primary flakes are those whose dorsal surfaces are entirely covered with cortex; secondary flakes have at least a trace of cortex on the dorsal surface; and tertiary (interior) flakes lack cortex, having derived entirely from the interior of the core. Primary flakes and secondary flakes are usually associated with the initial stages of
Prominent bulbs of force generally indicate that a hard hammer percussor (
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Other flake characteristics
The striking platform is the point on the proximal portion of the flake on which the detachment blow fell or pressure was placed. This may be natural or prepared. Termination type is a characteristic indicating the manner in which the distal end of a flake detached from a core. Flake terminations may be feathered, hinged, stepped, or plunging (also known as overshot or outrepassé). Feathered terminations are often very sharp, as the flake gradually reduces to a very fine thickness before the force exits the core and removes the flake. Hinged terminations are the result of the force rolling away from the core, resulting in a rounded distal end. Step terminations result when a flake prematurely breaks or snaps during removal, leaving a distal end that is often squared off. Plunging flakes are the result of the force rolling back towards the core and often taking off its "bottom". Hinge, step, and plunging terminations, although sometimes deliberately formed, are usually errors called "abrupt terminations". Abrupt terminations are often indicative of internal flaws in a core or previously formed Hertzian cones on the surface.[2] Eraillures, also referred to as "bulbar scars", are tiny flake scars that appear on some bulbs of applied force. The reason they form is not entirely understood. Of those flakes that do exhibit eraillures, very few have more than one.
Secondary and tertiary flakes display dorsal flake scars, which are simply the markings left behind by flakes detached prior to the detachment of the subject flake. These flake scars are one of the lines of evidence used to infer the method of lithic reduction, or the process by which raw material is turned into useful objects.
Tools
Flakes can be modified into formal tools, which result from additional working of the piece to shape a flake into a desired form, or they can be used without further modification, and are then referred to as expedient tools. For example, scrapers, which may be made by additional removals, known as retouchings, to the edge of a piece, or burins, which are created by a burin blow on the tip of a blade which produces a chisel-like edge which may have been used for graving and carving wood or bone. Because they require less labor to create, expedient flakes can be used strategically as a useful tool for a situation that does not necessarily require a sharpened tool necessary for cutting.[3]
References
- ^ a b c Andrefsky, W. (2005) Lithics: Macroscopic Approaches to Analysis. 2d Ed. Cambridge, Cambridge University Press
- ^ Macgregor, O.J. (2005) "Abrupt Terminations and stone artefact reduction potential". In Clarkson, C. and L. Lamb (Eds) (2005) Lithics 'Down Under': Australian Approaches to Lithic Reduction, Use and Classification. British Archaeological Reports International Monograph Series S1408. Oxford: Archaeopress
- S2CID 143220063.