Lithic flake

The energy of this blow propagates through the material, often (but not always) producing a Hertzian cone of force which causes the rock to fracture in a controllable fashion.

Since cores are often struck on an edge with a suitable angle (<90°) for flake propagation, the result is that only a portion of the Hertzian cone is created.

The process continues as the flintknapper detaches the desired number of flakes from the core, which is marked with the negative scars of these removals.

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.

At impact, concentric radii emanate from the point of percussion, but unlike conchoidal fracture, the force travels along what would be the center of the Hertzian cone.

More moderate and diffuse bulbs may indicate the use of a soft hammer percussor—such as bone, wood, or antler—which produces the bending flakes often associated with bifacial thinning and trimming.

The relative abundance of each type of flake can indicate what sort of lithic work was going on at a particular spot at a particular point in time.

Step terminations result when a flake prematurely breaks or snaps during removal, leaving a distal end that is often squared off.

Abrupt terminations are often indicative of internal flaws in a core or previously formed Hertzian cones on the surface.

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.