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IMAGINARY CENTER-LINE - In flint reduction it is necessary to imagine a center-line for the artifact.  Platforms are generally prepared below this center-line to assure a long, efficient, flake removal with clean feather termination. To strike a platform above this center line, one risks too short or a failed flake removal. 

ISOLATED PLATFORM - An isolated nipple or protrusion on the edge of a artifact, servicing for a more accurate strike in flake removal. 

PERCUSSION FLAKES - Flakes removed by the percussion process.  Percussion is attained by striking a platform with great force, allowing the knapper to remove much greater amounts of flint at one time than with pressure flaking. 

DELTAS - Flake ridges. A line or ridge formed by the intersection of two flake scars.  Platforms are usually made from delta edges and flake removal is usually designed to travel down them.  

PRESSURE FLAKES -  Pressure flakes are removed by applying pressure on a platform with enough force to make the flake detach from the artifact, this allows greater control for the knapper than by hitting it with percussion.  Pressure flaking scars are generally thinner, smaller, and less feathered than percussion.

CORTEX (RIND) - The outer surface or "bark" of  rock. It is formed on the exterior of stone by chemical and mechanical weathering processes.

FINGERNAIL - Fingernails are formed from when a flake fails to detach fully from the face of an artifact.  They are generally caused from insufficient force applied to detach the flake fully (resulting in step termination), or incorrect platform preparation.  Fingernails are often more visible on high quality or even heat treated materials.  Note: Fingernails are not always a good determiner for an artifacts authenticity.  Exposure to certain environments and material used seems to factor the most for fingernails.

OUTRE-PASSE - A highly specialized flaking technique that involves running a flake the full length of a blades face (edge to edge) before detaching, generally in a plunging termination.  Horizontal Transverse Flaking. This method has been long employed as a method for thinning an artifact quickly and efficiently.

DELTA TRIMMING - A retouch of the delta flakes.  Some of the earliest Clovis points (in first form) exhibit very little secondary pressure flaking but a minor trimming of the deltas.