The production of lithic artifacts depends upon the controlled removal of detached pieces from an objective piece. Often the detached pieces have characteristics of conchoidal fracture. Flakes with characteristics of conchoidal fracture are called ‘conchoidal flakes’ (Figure 2). Conchoidal flakes can be recognized as having two surfaces: a dorsal and a ventral surface.
The ventral surface is the surface that has broken away from the objective piece and is usually smooth and shows no evidence of previous flake removals. The dorsal surface is opposite the ventral surface and may show signs of the original exterior of the rock (‘cortex’) or of previous flake removals. Only the dorsal side of the conchoidal flake will have evidence of the original exterior of the rock. Specific properties of flakes are related to the technology used to detach the flake and can reveal information about the type of tool manufactured and the technique(s) used.
Typically, conchoidal flakes will have a point of applied force that removed the flake from the objective piece, known as a ‘striking platform’. Depending upon the physical characteristics of the original objective piece there are several different kinds of striking platforms. Some are flat, some are rounded, and others are angular with multiple facets. In some cases, there will be a projection at the base of the striking platform On the ventral surface of the flake known as a ‘lip’. A lip is formed as a result of impact with soft-hammer percussion or pressure flaking technology.
The end of the flake containing the striking platform is the ‘proximal end’. Opposite the proximal end is the ‘distal end’. The distal end of the flake is where the force of the original point of impact terminates. Different shapes of flake terminations reveal different kinds of information about the manner in which the flake was detached. The sides of the flake
Figure 1 Example of various tool and debitage types: (a), hafted biface; (b), unhafted biface; (c), coretool; (d), angular shatter; (e), flake tool; (f), proximal flake; (g), flake shatter.
Figure 2 Conchoidal flake showing common flake characteristics: (a), ventral side; (b), dorsal side.
Chipped stone artifacts Human modification? Yes=tool, No=debitage
Tool
Bifacial flaking? Yes=biface No=nonbiface
Debitage On flake?
Yes=flake debitage No=nonflake debitage
Nonbiface On flake?
Yes=flake tool No=core tool
Biface
Contains haft element? Yes=hafted biface No=unhafted biface
Flake debitage Nonflake debitage =
Contains striking platform? Angular shatter Yes=proximal flake No=flake shatter
Figure 3 Flowchart showing chipped stone typology with seven artifact types.
Between the proximal and distal ends where the dorsal and ventral sides meet are called the lateral margins. Lateral margins are often where the flake or blade is intentionally modified by the toolmaker or modified as a result of use.
The area below the striking platform on conchoidal flakes may have a raised hump on the ventral surface. This feature is called the ‘bulb of force’. The size and location of the bulb of force indicates the amount of load applied in the flake removal process and the density of percussor used. The bulb of force is always on the ventral surface of a flake, and never on the dorsal surface. Below the bulb of force and radiating away from the proximal end there may be compression rings. These rings show the direction of applied force as it traveled through the objective piece when the flake was detached. Another characteristic that is frequently found in association with the bulb of force is a scar from a small chip or flake on the bulb. This is called an ‘eraillure’ flake scar and is produced during the original impact of the flake removal.
World History
