Year: 2021
Type: article
Abstract: Natural alteration process of lithic artefactsAccording to Paul S. Hossfeld (1965), four terms, the first two more frequently, are used commonly in Australia to indicate such alterations.They are weathering, patination, desert polish, and desert varnish.Weathering is the geological term for a process that includes the changes that occur in a rock exposed to several atmospheric conditions.In general, two main weathering processes can be differentiated, which can influence the surface conditions of a lithic artefact, the physical and chemical weathering.Mechanical or physical weathering involves the breakdown of a part or parts of the stone artefact through direct contact with atmospheric conditions, such as heat, water, ice, and pressure.Chemical weathering involves the direct effect of chemicals of atmospheric or biological origin in the breakdown of a part or parts of the artefacts.Physical weathering is characteristic in very cold or very dry environments, chemical reactions are most intense under wet and hot climatic conditions.The degree of surface modification is extremely variable; it may imply a colour change, with or without a possible modification of the granularity of the texture, either solely on the surface (film) or more deeply (Inizan et al. 1999, 91).Patina is an extremely thin surface film or skin.Except for the rare instances where the effects of weathering are in their early stages and noticeable as a thin film only of altered material on the surface, there is no difficulty in distinguishing patina from weathering.Patination of materials other than flint is of importance.In the drier areas of Australia, patination affects stones other than flints, such as quartzites and igneous rocks.Although it forms a veil or skin on weathered and unweathered rocks, it is distinct from an existing weathered crust.This veil may consist of crystalline silica over flint or similar materials, or iron oxides or mixtures of these with silica, but all of them are due to chemical action and therefore termed "chemical patination".Another surface phenomenon is known as desert polish, which is distinct from the gloss patina.The glossiness and lustre of this form of patination are produced by the frictional action of windblown sand and dust.It is being termed "mechanical patination."(see, also, Perry et al. 2005).Another coating referred to by some authors is known as desert varnish.It is a black, manganeserich rock coating.The thickness of this coating is variable, as it covers not only the outer surfaces Knapping techniquesGeneral information on knapping techniques is available in several pieces of literature, such as Crabtree (1972), Whittaker (1994) and Inizan and colleagues (1999).In the following, the author will confine himself to a brief description of the most necessary concepts.
Source: Litikum
Author: Attila Péntek
Language: English
Subfield: Anthropology
Field: Social Sciences
Domain: Social Sciences
Open Access status: diamond
OpenAlex ID: W4386092450