Block On Block or Anvil / Clactonian / Levalloisian Technique
ฝัง
- เผยแพร่เมื่อ 24 ส.ค. 2024
- Block-On-Block:
In this technique the pebble or block of stone to be worked is struck against the projecting point of a large fixed stone or anvil. The bulbs produced in this kind of flaking can be really pronounced as the force with which the stone hits the anvil is supplemented by the natural weight of the rock.
The above methods have a risk of having no control over the fracture and hence can often defeat the purpose. The following controlled methods of stone fabrication were evolved to overcome this risk.
Clactonian Flaking:
Strictly speaking this method is not a combined method but we list it here because it involves a special planning. This is the oldest flaking technique known from the British Lower Palaeolithic. The name is derived from the site Clacton-on-Sea in Essex. These flakes are known from all over Europe during various stages of Palaeolithic culture. These are essentially typified by a characteristic high flake angle and a general absence of secondary retouchings on them.
It is a common experience that to detach a flake from a pebble one has to strike a blow in an inclined manner. The angle of this direction of force with the pebble surface is therefore always less than 90° for obtaining a good sized flake. For removing a second flake from the same surface one requires increasing the angle of the blow. If this process is repeated a stage comes when the blow delivered is at right angles-and the core in this case, shatters in several pieces instead of giving a flake.
Hence this is known as the critical angle of percussion. The Clactonian technique eliminates this limitation of simple percussion technique. Here once a flake is removed from one surface this flaked surface is used as the striking platform to remove another fresh flake from the opposite surface. As a result the flake angle of each Clactonian flake comes out as more than 90°.
Levallois Technique:
This technique is named after a site of this name in the suburb of Paris. It involves taking out of a number of flakes from one face of a nodule from all around its periphery in a centripetal manner as a first step. This prepared core resembles a tortoise shell and therefore is usually referred to as tortoise core.
Finally a calculated blow is delivered on the top of the shaped surface in such a manner that a flake comes out of this core. The detached flake carries the previous dressing on its dorsal surface. It is, therefore, taken to be a technique where a previous planning and shaping of a flake to be detached is perfected.
In other words this marks a technological development in prehistoric techniques which needs to be counted in the assessment of the characteristics of a given industry or culture. For long it has been emphasized that the diagnostic trait for the identification of a levallois flake is the occurrence of a faceted butt.
In reality there are many normal flakes known with faceted butts and also numerous levallois flakes known without any kind of faceting present at their butt ends. The only feature which goes to define a levallois flake is the occurrence of centrally directed flake scars on its dorsal surface.
Many or some of these dorsal surface flake scars do not have their points of impact on this flake (that is, the flake detached cuts a portion of the previous dressing from the tortoise core. Thus, most of the points of impact of these scars are retained on the core while the flake detached maintains only the distal ends of these scars).
Besides this, the butt end of a levallois flake is rarely known to have formed an angle of more than 90° with the axis of the flake scar. Levallois technique can be modified by choosing and shaping special cores and thus producing levallois points and levallois blades.
#basicknowledge248
#ArchaeologicalAnthropology