| Fracture features
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| Morphological features found on flakes can be described using well established terms. These terms are often illustrated using a drawing such as the one shown below. Each unbroken flake has three surfaces. The surface onto which the indenter was placed is called the striking platform (sometimes abbreviated to 'platform'). The surface formed by the fracture that created the flake is called the ventral face. The third surface, which was the exterior of the rock before the flake was removed, is called the dorsal face.
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In addition to these surfaces there are some generalised descriptions of the different zones of a flake. The end of the flake containing the striking platform is termed the proximal end, whereas the portion of the flake containing the fracture termination is called the distal end. In addition, the two edge formed by the junction of the ventral and dorsal faces are termed the lateral margins. Using these terms it is possible to describe the location on a flake of any feature of interest.
Beginning with the ventral surface it is possible to illustrate the various features found on flakes.
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| At the extreme proximal end of the flake, at the junction of the platform and the ventral surface it is often possible to see the ring crack as a semi-circular protruberance. On fine-grained materials ringcrack features are pronounced.
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Below the ringcrack there is a distinct convexity called the bulb of force. This bulge is often smooth and gently curved, but may sometimes contain a depression known as an eraillue scar. |
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At the distal end of the ventral surface the fracture termination can be seen. The terminination is often described on the basis of the bend in the fracture plane that can be seen from the side (see below). |
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| Many of these features can also be seen from the side. In the photograph below and left the dorsal surface is on the left while the ventral surface is on the right. At the junction between those surfaces the lateral margin clearly runs from the proximal to distal end of the flake.
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|  | PROXIMAL END is where the fracture is initiated. From this lateral view the flat striking platform is visible at an angle to the ventral surface. It was on the platform that the blow was applied, and the ringcrack is therefore found at the junction of the platform and ventral face. |
| | From the side the protruding bulb of force is easily visible towards the proximal end and below the ringcrack. |
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DISTAL END is where the fracture finishes, thereby creating the flake as a separate object from the core. A termination in which the fracture plane gradually converges with the free surface is called a 'feather termination' (shown on the left). When the fracture plane bends sharply towards the free surface it is called a 'hinge termination' (see photograph below). These are two common terminations, although others do occur.
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| Hinge termination.
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| On the dorsal surface of a flake there is usually a number of negative flakes scars left by the previous removal of flakes. These scars contain the full detail of ventral surfaces, but in the negative (eg. where the bulb is a convex area on a ventral surface it is a concavity on a scar). Because of this it is possible to identify the location of fracture initiation on each previous scar, and to determine the location and direction of blows that removed each of the flakes evidenced by the scars. In the specimen to the left all negative flake scars were created by blows applied to the proximal end of the flake. |
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Author: Peter Hiscock, Dept. Archaeology and Anthropology, Australian National University.
Feedback:  peter.hiscock@anu.edu.au.
Date Last Modified: Thursday, 1-May-97
URL: http://artalpha.anu.edu.au/web/arc/resources/intro/feat.htm
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