Editing Hand axe (section)

==Morphology==
[[File:Bifaz-esquema.png|thumb|right|upright|Basic scheme for the morphological description of an Acheulean hand axe.]]
Hand axes have traditionally been oriented with their narrowest part upwards (presupposing that this would have been the most active part, which is not unreasonable given the many hand axes that have unworked bases). The following typological conventions are used to facilitate communication. The [[symmetry axis|axis of symmetry]] that divides a biface in two is called the ''morphological axis.'' The ''main face'' is usually the most regular and better worked face. The ''base'' (not the ''heel'') is the bottom of the hand axe.<ref name=fritisa/>

*Terminal zone—the narrowest end, opposite the base. Its most common shape is pointed, more or less acute or oval. Some hand axes have terminal ends that are rounded or polygonal (i.e. not pointed) while others have terminal ends that are transversal to the axis, called [[cleaver]] or spatulate.
*Proximal end (base)—opposite the terminal end (usually broader and thicker), it can be described as either ''reserved'' (partially or totally worked, but not cut); or ''cut'', with a rounded (polygonal), flat or pointed end.
*Edges—convex, rectilinear or concave, and more or less even. Edges on some specimens are [[Denticulate tool|denticulate]]—scalloped—or notched. Some specimens have unsharpened edges. The profile of a hand axe's worked edges can be regular without pronounced [[line (geometry)|rectilinear]] deviations (the edge is gently curved in the form of an [[S]]) or an edge may be more sinuous and wave-formed with pronounced curves or deviations in the edge's profile. On some specimens only selected areas have been formed into a working edge.
*[[Cross section (geometry)|Cross section]]—the horizontal cross-section taken at some distance from the base. It is possible to discern retouching or rebuilding in deteriorated parts of the edges. The following types of cross section are commonly seen: [[triangle|triangular]] (sub-triangular and backed triangular), [[rhombus|rhombic]] ([[rhomboid]]al and backed rhomboidal), [[Quadrilateral|trapezium]] ([[trapezoid]] and backed trapezoidal), [[pentagon]] (pentagonal and backed pentagonal), [[polygon]]al, biconvex or lenticular (sub lenticular).
*Profile—By definition, hand axes have a roughly balanced outline, with a morphological axis that also serves as an axis of [[Symmetry in biology|bilateral symmetry]] and a plane that serves as an axis of [[Isometry|bifacial symmetry]]. Not all hand axes are perfectly symmetrical. Symmetry was achieved only after millennia of development. Symmetry may not make tools more useful. Hand axes were used in a variety of heavy physical tasks. They deteriorated, wore out and broke and were often repaired with retouching of their edges, recovery of their points or complete reworking. The majority of discovered pieces are remains, pieces that have been discarded after a long life as tools, during which they often were damaged and/or adapted for specialized tasks. Such pieces may have lost whatever symmetry they initially had. Hand axe profiles can be classified into the following categories:
{| class="wikitable" style="width:30%; margin: auto; background-color: white"
|+ Biface profiles
|- style="vertical-align: bottom"
|[[File:Biface triangulaire.png|center|75px|thumb|Triangular]]
|[[File:Biface amygdaloide.png|center|100px|thumb|Amygdaloidal]]
|[[File:Biface flexueux.png|center|100px|thumb|Cordiform]]
|[[File:Coup de poing acheléen.jpg|center|70px|thumb|Lanceolate]]
|[[File:Biface.jpg|center|90px|thumb|Micoquien]]
|- style="vertical-align: bottom"
|[[File:Biface discoide.png|center|100px|thumb|Discoid]]
|[[File:Biface ovalaire.png|center|80px|thumb|Ovoid]]
|[[File:Biface limande.png|center|100px|thumb|Elliptical]]
|[[File:Biface naviforme.png|center|100px|thumb|Naviform]]
|[[File:Biface losangique.png|center|100px|thumb|Rhombic]]
|- style="vertical-align: bottom"
|[[File:Biface-hachereau.png|center|70px|thumb|Splitter]]
|[[File:Biface lageniforme.png|center|100px|thumb|Spatulate]]
|[[File:Biface abbevillien.png|center|90px|thumb|Abbevillian]]
|[[File:Biface nucleiforme.png|center|105px|thumb|Nucleiform]]
|[[File:Question mark.svg|center|50px|thumb|Others]]
|}

===Dimensions and ratios===
[[File:Bifaz dimensiones.svg|thumb|upright=1.5|Basic dimensions to be measured on an Acheulean hand axe.]]

Hand axe measurements use the morphological axis as a reference and for orientation. In addition to length, [[width]], [[Three-dimensional space|depth]], specialists have proposed a wide range of other [[physical quantity|physical quantities]]. The most common were proposed by Bordes<ref name=bordes/>{{rp|51}} and Balout:<ref name=balout/>

*Maximum length ('''L''')
*Maximum width ('''m''')
*Maximum depth ('''e''')
*Distance from the base to the zone with the maximum width ('''a''')
*Width 3/4 of the way along the piece ('''o''')

'''A''' and '''o''' can be used to delineate the contour's cross section and to measure the angles of the edges (provided this is not an area covered in the stone's original cortex). These [[Degree (angle)|angular measurements]] for the edges are made using a [[goniometer]].

Edge length, weight and the length of the [[Circle#Properties#chord|chord]] described by the edges (if the piece has a transverse terminal bezel) can be measured. These measurements allow morphological and technical ratios to be established (for example, the relationship between the weight and the length of the cutting edges, or the relationship between the hammer used to form the piece and the angle obtained etc.).

The most commonly used coefficients were established by Bordes for the morphological-mathematical classification of what he called "classic bifaces" (Balout proposed other, similar indices):<ref>They are the ''Elongation index'', the ''Sectional index'' and the ''Convergence index'', {{harvnb|Balout|1967}}</ref>

{{unordered list
|Base-rounding index—allows classic bifaces to be separated into triangular, almond-shaped and oval families. The '''L/a''' ratio provides the following separation thresholds:
{{clear}}
{{wikitable| style="background-color:#F0F0F0" cellspacing{{=}}"10"
|-
!style{{=}}"background-color:white" rowspan{{=}}4|[[File:Bifaz-Redondeamiento de la base.gif|left|110px]]
!style{{=}}"background:#e2e4c0"|Family
!style{{=}}"background:#e2e4c0"|Threshold
|-
|''Triangular bifaces'' (the most regular)<br />or ''sub triangular'' (for the irregular ones)||style{{=}}"text-align:center"|<math>{\frac{L}{a}}<2.75</math>
|-
|''Almond-shaped bifaces''||style{{=}}"text-align:center"|<math>2.75<{\frac{L}{a}}<3.75</math>
|-
|''Oval bifaces''||style{{=}}"text-align:center"|<math>3.75<{\frac{L}{a}}</math>
}}

|Elongation index—separates common bifaces from the ''short'' (and, occasionally, from the ''elongated''). For example, within the family of ''Oval bifaces'' the index distinguishes discoidal bifaces from other types; in the ''Almond-shaped bifaces'' it identifies lanceolate or micoquien bifaces. The index is calculated using '''L/m.''' Thresholds:
{{wikitable| style="background-color:#F0F0F0" cellspacing{{=}}"10"
|-
!style{{=}}"background-color:white" rowspan{{=}}4|[[File:Bifaz-indice de alargamiento.gif|left|110px]]
!style{{=}}"background:#e2e4c0"|Elongation
!style{{=}}"background:#e2e4c0"|Threshold
|-
|''Short bifaces''||style{{=}}"text-align:center"|<math>{\frac{L}{m}}<1.3</math>
|-
|''Common bifaces''||style{{=}}"text-align:center"|<math>1,3<{\frac{L}{m}}<1.6</math>
|-
|''Elongated bifaces''||style{{=}}"text-align:center"|<math>1.6<{\frac{L}{m}}</math>
}}

|Cross-sectional/planar index—divides the ''thick'' bifaces from the ''flat'' ones and is used only on certain types. In the ''Almond-shaped bifaces'' (along with the elongation index) it distinguishes the amygdaloid bifaces (thick) from the cordiform bifaces (flat). The index is calculated using '''m/e.''' Thresholds:
{{wikitable| style="background-color:#F0F0F0" cellspacing{{=}}"10"
|-
!style{{=}}"background-color:white" rowspan{{=}}3|[[File:Bifaz-indice de aplastamiento.gif|left|110px]]
!style{{=}}"background:#e2e4c0"|Cross section
!style{{=}}"background:#e2e4c0"|Threshold
|-
|''Thick bifaces''||style{{=}}"text-align:center"|<math>{\frac{m}{e}}<2.35</math>
|-
|''Flat bifaces''||style{{=}}"text-align:center"|<math>{\frac{m}{e}}>2.35</math>
}}

|Other indexes apply to the other types of bifaces (partial bifaces, bifaces with an unworked base, or cleaver, spatulate, Abbevillean, nucleiform, etc.).}}