Lithic reduction

Lithic reduction involves the use of a hard hammer percussor, such as a hammerstone, a soft hammer fabricator (made of wood, bone or antler), or a wood or antler punch to detach lithic flakes from a lump of tool stone called a lithic core (also known as the "objective piece"). As flakes are detached in sequence, the original mass of stone is reduced; hence the term for this process. Lithic reduction may be performed in order to obtain sharp flakes, on which a variety of tools can be made, or to rough out a blank for later refinement into a projectile point, knife, or other object. Flakes of regular size that are at least twice as long as they are broad are called blades. Lithic tools produced this way may be bifacial (exhibiting flaking on both sides) or unifacial (exhibiting flaking on one side only).

Cryptocrystalline or amorphous stone such as chert, flint, obsidian, and chalcedony, as well as other fine-grained stone material, such as rhyolite, felsite, and quartzite, were used as a source material for producing stone tools. As these materials lack natural planes of separation, conchoidal fractures occur when they are struck with sufficient force. The propagation of force through the material takes the form of a Hertzian cone that originates from the point of impact and results in the separation of material from the objective piece, usually in the form of a partial cone, commonly known as a lithic flake. This process is predictable, and allows the flintknapper to control and direct the application of force so as to shape the material being worked.

Removed flakes exhibit features characteristic of conchoidal fracturing, including striking platforms, bulbs of force, and occasionally eraillures (small secondary flakes detached from the flake's bulb of force). Flakes are often quite sharp, with distal edges only a few molecules thick, and can be used directly as tools or modified into other utilitarian implements, such as spokeshaves and scrapers.

Techniques

Percussion reduction

Percussion reduction, or percussion flaking, refers to removal of flakes by striking a core or other objective piece, such as a partially formed tool, with a hammer or percussor. Alternatively, the objective piece can also be struck against a stationary anvil-stone, known as bipolar percussion. Percussors are traditionally are either a stone cobble or pebble, often referred to as a hammerstone, or a billet made of bone, antler, or wood. Often, flakes are struck from a core using a punch, in which case the percussor never actually makes contact with the objective piece. This technique is referred to as indirect percussion. (Andrefsky 2004:12)

Hard-Hammer Percussion

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An example of hard hammer precussion.
Hard hammer techniques are generally used to remove large flakes of stone. Early flintknappers and hobbyists replicating their methods often use cobbles of very hard stone, such as quartzite. This technique can be used by flintknappers to remove broad flakes that can be made into smaller tools. This method of manufacture is believed to have been used to make some of the earliest stone tools ever found, some of which date from over 2 million years ago.

It is the use of hard-hammer percussion that most often results in the formation of the typical features of conchoidal fracture on the detached flake, such as the bulb of percussion and compression rings (Cotterell and Kamminga 1987:986)

Soft-Hammer Percussion

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An example of soft hammer precussion
Soft-hammer percussion involves the use of a billet, usually made of wood, bone or antler as the percussor. Flakes produced in this manner are generally smaller and thinner than those produced by hard-hammer flaking, thus, soft-hammer flaking is often used after hard-hammer flaking in a lithic reduction sequence to do finer work.

In most cases, the amount of pressure applied to the objective piece in soft-hammer percussion is not enough for the formation of a typical conchoidal fracture. Rather, soft-hammer flakes are most often produced by what is referred to as a bending fracture, so-called because the flake is quite literally bended or "peeled" from the objective piece. Flakes removed in this manner lack a bulb of percussion, and are distinguished instead by the presence of a small lip where the flake's stiking platform has separated from the objective piece (Andrefsky 2005:18-20; Cotterell and Kamminga 1987:690).

Pressure flaking

Enlarge picture
An example of pressure flaking
In lithic reduction, pressure flaking is a method of trimming the edge of a stone tool by removing small lithic flakes by pressing on the stone with a sharp instrument rather than striking it with a percussor. This method, which often uses punches made from bone or antler tines (or, among modern hobbyists, copper punches or even nails), provides a greater means of controlling the direction and quantity of the applied force than when using even the most careful percussive flaking. Usually, the objective piece is held clasped in the flintknapper's hand, with a durable piece of fabric or leather protecting the flintknapper's palm from the sharpness of the flakes removed. The tip of the flaking tool is placed against the edge of the stone tool and pressed hard, removing a small linear or lunate flake from the opposite side. In some instances, a hammer and punch is used while the tool is held down with a vice. The process also involves frequent preparation of the edge to form better platforms for pressing off flakes. This is usually accomplished with abraders made from a coarse-grained stone such as basalt or quartzite. Great care must be taken during pressure flaking so that perverse fractures that break the entire tool do not occur. Occasionally, outrepasse breaks occur when the force propagates across and through the tool in such a way that the entire opposite margin is removed.

The use of pressure flaking facilitated the early production of sharper and more finely-detailed tools. Pressure flaking also gave toolmakers the ability to create notches where the objective piece could be bound more securely to the shaft of the weapon or tool and increasing the objects utility.

References

Andrefsky, W. (2005) Lithics: Macroscopic Approaches to Analysis. Cambridge: Cambridge University Press. ISBN 0521615003

Cotterell, B. and Kamminga, J. (1987) The Formation of Flakes. American Antiquity 52:675-708

See also

In archaeology, a hammerstone is a hard cobble used to strike lithic flakes off a lump of tool stone during the process of lithic reduction. Often, a hammerstone is made of a material such as limestone or quartzite, is ovoid in shape (to better fit the human hand), and develops
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The WOOD callsign may refer to:
  • WOOD-TV – an NBC-affiliated television station in Grand Rapids, Michigan
  • WOOD (AM) – an AM radio station in Grand Rapids, Michigan
  • WOOD-FM - an FM radio station in Grand Rapids, Michigan




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Bones are rigid organs that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red and white blood cells and store minerals.
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Antlers are the large and complex horn-like appendages of male deer, consisting of bony outgrowths from the head with no covering of keratin as is found in true horns. Each antler grows from an attachment point on the skull called a pedicle.
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A punch is a hard metal rod with a shaped tip at one end and a blunt butt end at the other that is usually struck by a hammer. A variety of punches are used in engineering, but often the purpose is to form an impression of the tip on a workpiece.
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lithic flake is a thin, sharp fragment of stone that results from the process of lithic reduction. Once the proper tool stone has been selected, a fabricator is used to direct a sharp blow to the surface of the stone.
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In archaeology, a tool stone is a type of stone that is used to manufacture stone tools. Generally speaking, tools that require a sharp edge are made using cryptocrystalline materials that fracture in an easily-controlled conchoidal manner.
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In archaeology, a lithic core is a distinctive artifact that results from the practice of lithic reduction. In this sense, a core is the scarred nucleus resulting from the detachment of one or more flakes from a lump of source material or tool stone, usually by using a hard hammer
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In archaeology, a projectile point is an object that was hafted and used either as knife or projectile tip or both, commonly called an arrowhead. Occasionally, projectile points made of worked bone or ivory are found at archaeological sites, but generally the term is reserved for
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In archaeology a blade is a type of stone tool created by striking a long narrow flake from a stone core.

Blades are defined as being flakes that are at least twice as long as they are wide and that have parallel or subparallel sides and at least two ridges on the dorsal
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biface is a two-sided stone tool, manufactured through a process of lithic reduction, that displays flake scars on both sides. A profile view of the final product tends to exhibit a lenticular shape (i.e., as a convex lens).
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uniface is a specific type of stone tool that has been flaked on one surface only. Such tools can be placed into two general classes: 1) modified flakes and 2) formalized tools, which display deliberate, systematic modification of the marginal edges and were often formed with a
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Cryptocrystalline is a rock texture which is so finely crystalline, that is, made up of such minute crystals that its crystalline nature is only vaguely revealed even microscopically in thin section by transmitted polarized light.
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Chert (IPA: /ˈtʃəː(r)t/) is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils.
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Flint (or flintstone) is a hard, sedimentary cryptocrystalline silicate form of the mineral quartz, categorized as a variety of chalcedony and broadly part of the mineral group known as silicas.
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Obsidian is a type of naturally-occurring glass formed as an extrusive igneous rock. It is produced when felsic lava erupted from a volcano cools rapidly through the glass transition temperature and freezes without sufficient time for crystal growth.
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Chalcedony is a cryptocrystalline form of silica, composed of very fine intergrowths of the minerals quartz and moganite[1]. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, whilst moganite is monoclinic.
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Rhyolite is an igneous, volcanic (extrusive) rock, of felsic (acidic) composition (typically >69% SiO2 — see the TAS classification. It may have any texture from aphanitic to porphyritic.
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This article on a cryptocrystalline igneous rock may contain original research or unverified claims.
Please help Wikipedia by adding references. See the for details.
This article has been tagged since April 2nd, 2007 at 9:34:25PM|.

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<noinclude></noinclude> Quartzite (from German Quarzit[1]) is a hard, metamorphic rock which was originally sandstone.[2] Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within
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Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types:
  • Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes.

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Conchoidal fracture describes the way that brittle materials break when they do not follow any natural planes of separation. Materials that break in this way include flint and other fine-grained minerals, as well as most amorphous solids, such as obsidian and other types of glass.
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A Hertzian cone is cone of force that propagates through a brittle, amorphous or cryptocrystalline solid material from a point of impact, eventually removing a full or partial cone.
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lithic flake is a thin, sharp fragment of stone that results from the process of lithic reduction. Once the proper tool stone has been selected, a fabricator is used to direct a sharp blow to the surface of the stone.
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In lithic reduction, the striking platform is the surface on the proximal portion of a lithic flake on which the detachment blow fell; this may be natural or prepared. Types of striking platforms include:

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In lithic analysis (a subdivision of archaeology), an eraillure is a small secondary flake removed from a lithic flake's bulb of force, which is a lump left on the ventral surface of a flake after it is detached from a core of tool stone during the process of lithic reduction.
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In lithic analysis, a subdivision of archaeology, a bulb of applied force (also known as a bulb of percussion or simply bulb of force) is a defining characteristic of a lithic flake.
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A spokeshave is a tool used to shape and smooth wooden rods and shafts - often for use as wheel spokes, chair legs (particularly complex shapes such as the cabriole leg),[1] or arrows. It can also be used to carve canoe paddles.
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Scrape may refer to:

Tools

  • Bottle scraper, for removing content from bottles
  • Card scraper, for smoothing wood or removing old finish
  • Hand scraper, for finishing a metal surface
  • Ice scraper, for removing ice from windows

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In archaeology, a lithic core is a distinctive artifact that results from the practice of lithic reduction. In this sense, a core is the scarred nucleus resulting from the detachment of one or more flakes from a lump of source material or tool stone, usually by using a hard hammer
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