Editing Hand axe (section)

===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.).}}