Editing Hand axe (section)

===Hard hammer faces===
Hand axes can be made without subsequent reworking of the edges.<ref name="alimen">{{cite book|author-link=Henriette Alimen|last1=Alimen|first1= Marie-Henriette|last2=Zuate y Zuber|first2= José|chapter=Les bifaces: considerations morphologiques et technologiques|title=L'évolution de l'Acheuléen au Sahara nord-occidental|lang=fr|trans-chapter=Bifaces: morphological and technological considerations|trans-title=Evolution of the Acheulean in the northwestern Sahara|year=1978|publisher=Centre National de la Recherche Scientifique |location=Meudon, France|pages=120–121}}</ref> A [[hammerstone]] was the most common percussive tool used during the Acheulean. The resulting artefact is usually easily recognizable given its size and irregular edges, as the removed flakes leave pronounced [[bulb of percussion|percussion bulbs]] and compression rings.<ref>{{cite journal |last1=Cotterell |first1=Brian |last2=Kamminga |first2=Johan |title=The Formation of Flakes |journal=American Antiquity |date=October 1987 |volume=52 |issue=4 |pages=675–708 |doi=10.2307/281378 |jstor=281378 |s2cid=163565502 }}</ref> A hammerstone produces a small number of flakes that are wide and deep leaving long edges on the tool as their highly concave form yields curving edges. The cross-section is irregular, often sub-rhombic, while the intersection between the faces forms an acute angle of between 60° and 90° degrees. The shape is similar to that of the core as the irregularities formed during knapping are not removed. The notches obtained were exploited in the production sequence. It is common that this type of manufacture yields "partial bifaces" (an incomplete working that leaves many areas covered with cortex), "unifaces" (tools that have only been worked on one face), "[[Abbevillian|bifaces in the Abbevillian style]]" and "nucleiform bifaces". This type of manufacturing style is generally an indication of the age when a tool was made and with other archaeological data can provide a context that allows its age to be estimated.