Stone Tool Analysis: Face shear

In wedging initiations, the crack is initiated by a relatively hard percussion blow, often combined with the compression effects of resting the core on a hard anvil.  A wedging initiation is essentially a split, and hence there is no platform like that occurring on flakes initiated conchoidally or by bending.  A wedge-initiated scar is flat rather than convex, lacks a bulb of force, and has a ‘sheared’ appearance.  


Flake, block-on-block, Mithaka

Quarry Debris

Flake, wedging initiation, Australia


Bipolar core, Indiana

Bipolar Core

The proximal end of the wedging-initiated flake is often a sharp edge, and frequently crushed.  The crack path in wedging initiations is often highly unstable and exceptionally prominent and closely-spaced undulations will radiate from the point of force initiation, or PFA.  Linear hackles and splits are often present, also radiating out from the PFA.  Eraillures, ring cracks, umboes, and platform lips are not present on wedge-initiated scars and flakes.