The mechanical properties of heat-treated rocks: a comparison between chert and silcrete

Schmidt, Patrick; Buck, Gerald; Berthold, Christoph; Lauer, Christoph; Nickel, Klaus G.

doi:10.1007/s12520-018-0710-y

Cited by 37 publications

(45 citation statements)

References 63 publications

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“…Since the 1960s several experiments have been carried out on the effects of heat treatment of silica rocks (see among others, Crabtree and Butler, 1964;Inizan et al, 1976;Purdy and Brooks, 1971). Heat treatment causes mechanical transformations of silica rocks (for example flakeability) (Schmidt et al, 2018b). However, it also causes different types of visible alteration.…”

Section: Macroscopic Recognition Of Heat-treatmentmentioning

confidence: 99%

“…The result of such post-heat treatment knapping is surface gloss. It is caused by changing fracture pattern due to modified mechanical properties of the material (Schmidt et al, 2018b) and is therefore only visible if the artefact is worked after heating (Crabtree and Butler, 1964;Domanski and Webb, 1992;Inizan et al, 1976;Masson, 1981;Purdy and Brooks, 1971). The intensity of this gloss depends mainly on the temperature reached during heating but also on the type of rock (Inizan et al 1976;Masson, 1981;Domanski and Webb, 1992).…”

Section: Macroscopic Recognition Of Heat-treatmentmentioning

confidence: 99%

“…Heat treatment modifies the mechanical properties of silica rocks. It is known to improve knapping quantity and the cutting edges of the finished object were found to be sharper (see among others, Anderson, 1978; Boix Calbet, 2012; Collins and Fenwick, 1974; Crabtree and Butler, 1964;Domanski and Webb, 1992;Flenniken and Garrison, 1975;Inizan et al, 1976;Léa et al, 2012;Mandeville, 1973;Masson, 1981;Purdy, 1974;Purdy and Brooks, 1971; Roqué-Rosell et al, 2011; Schmidt, 2011; Terradas and Gibaja, 2001;Tiffagom, 2006;Torchy, 2013, Schmidt et al, 2018b. In France, Solutrean heat treatment was identified in the 1960s-70s when heat-treated laurel-leaf points were found on the sites of Laugerie-Haute and Le Placard (Bordes, 1967(Bordes, , 1969Collins, 1973;Inizan et al, 1976).…”

Section: Introductionmentioning

confidence: 99%

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Technical innovations during the recent Solutrean in the southwest of France: Recognition of heat treatment of chert and estimation of heating temperatures based on the example of Le Piage (Lot, France)

Bachellerie

Renard

Schmidt

2019

Journal of Archaeological Science: Reports

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The Solutrean technocomplex is characterized by the use of innovative techniques for stone tool knapping during the Upper Palaeolithic. These processes include the development of pressure retouch and heat treatment of silica rocks. These innovations remain unprecedented at the scale of the recent European Paleolithic. The aim of our analysis is to acquire new information on the application of heat treatment, by investigating the heating technique and the lithic chaîne opératoire in which this treatment occurs. Macroscopic observations of the material combined with an infrared spectroscopic analysis of 69 archaeological samples provide new data on heat treatment in the Solutrean lithic series of Le Piage (Fajoles, Lot). Raw materials were heated in controlled conditions and to temperatures of 250-300°C. We also found that only leaf-shaped pieces were heat-treated at Le Piage. Part of the results obtained by infrared spectroscopy reveal discrepancies with macroscopic observations. These data raise questions concerning the validity of common macroscopic criteria used for recognising heat treatment and shed light on some of the choices made by Solutrean groups.

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Section: Macroscopic Recognition Of Heat-treatmentmentioning

confidence: 99%

Section: Macroscopic Recognition Of Heat-treatmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Technical innovations during the recent Solutrean in the southwest of France: Recognition of heat treatment of chert and estimation of heating temperatures based on the example of Le Piage (Lot, France)

Bachellerie

Renard

Schmidt

2019

Journal of Archaeological Science: Reports

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“…At least one example (Fig. 3, n°9) shows that heat treatment was also applied to local coarse-grained silcrete (this type of coarse-grained silcrete does often not produce unambiguous heating proxies, see: Schmidt et al, 2019).…”

Section: Raw Materials Acquisition and Silcrete Heat Treatmentmentioning

confidence: 99%

Experimentation preceding innovation in a MIS5 Pre-Still Bay layer from Diepkloof Rock Shelter (South Africa): emerging technologies and symbols

Porraz¹,

Parkington²,

Schmidt³

et al. 2020

Preprint

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In South Africa, key technologies and symbolic behaviors develop as early as the later Middle Stone Age in MIS5. These innovations arise independently in various places, contexts and forms, until their full expression during the Still Bay and the Howiesons Poort. We elaborate here on the Middle Stone Age sequence of Diepkloof Rock Shelter (South Africa) and focus on the Stratigraphic Unit Lynn, which immediately precedes the Still Bay at the site. The pre-Still Bay Lynn documents the transport of rocks over long distance (>20 km), the heat treatment of silcrete, the coexistence of seven lithic reduction strategies (including the production of bladelets and the manufacture of unifacial and bifacial points), the use of adhesives and the processing of ochre. Beside this set of novelties, the layer yields one of the oldest abstract engravings so far discovered in Africa, taking the form of cross-hatched markings in the cortical surface of an ungulate long bone shaft. At Diepkloof, these new practices appear in a context that demonstrates a shift in rock procurement and a diversification in lithic reduction strategies, suggesting these behavioral practices acted as a cultural answer to cope with new environmental and/or socio-economical circumstances. We argue that the innovations later found during the Still Bay and the Howiesons Poort were then already in the making during the MIS5 pre-Still Bay, though not all the benefits were yet taken advantage of by the populations.

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“…Barremian-Bedoulian flint contains ‘water’ in the form of chemically bound water (SiOH) of ~56 wt% and as molecular water (H 2 O) in fluid inclusions of ~0.33 wt%; it encloses a total intergranular pore volume of ~0.65 vol% [36]. All these characteristics confer a good knapping quality to this type of flint, including good homogeneity in terms of force transmission, high fracture strength and low fracture toughness [37], and provide the possibility to heat-treat the rocks to improve knapping quality even further [38].…”

Section: Barremian-bedoulian Flint At Gavà Minesmentioning

confidence: 99%

The status of imported Barremian-Bedoulian flint in north-eastern Iberia during the Middle Neolithic. Insights from the variscite mines of Gavà (Barcelona)

et al. 2019

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Barremian-Bedoulian flint from the Vaucluse region (western Provence, SE France), is traditionally considered one of the most significant chrono-cultural markers of the Chasséen culture during the Middle Neolithic (end of the 5th and beginning of the 4th millennium BC). Diffusion of Provençal flints became massive during the first half of the 4th millennium BC, penetrating in several neighbouring cultural spheres such as the Sepulcros de Fosa culture in north-eastern Iberia. The integrated study of the lithic assemblages from the variscite mines of Gavà (Barcelona) and its contextualization within the Sepulcros de Fosa culture in north-eastern Iberia have revealed unexpected complexity in the modes of consumption, use and status of imported Barremian-Bedoulian industries in north-eastern Iberia during the 5th to 4th millennia cal. BC transition. Local communities within this region, already controlling extraction and regional diffusion of variscite ornaments, exerted control over the fluxes of Vauclusian flint south of the Pyrenees, where it had a triple status (functional, symbolic and both). In addition, the results provide complementary data to better understand relevant aspects of the nature and organisation of Barremian-Bedoulian flint exploitation and early supply systems at the Provençal producing sites during the later phase of the Chasséen culture.

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The mechanical properties of heat-treated rocks: a comparison between chert and silcrete

Cited by 37 publications

References 63 publications

Technical innovations during the recent Solutrean in the southwest of France: Recognition of heat treatment of chert and estimation of heating temperatures based on the example of Le Piage (Lot, France)

Technical innovations during the recent Solutrean in the southwest of France: Recognition of heat treatment of chert and estimation of heating temperatures based on the example of Le Piage (Lot, France)

Experimentation preceding innovation in a MIS5 Pre-Still Bay layer from Diepkloof Rock Shelter (South Africa): emerging technologies and symbols

The status of imported Barremian-Bedoulian flint in north-eastern Iberia during the Middle Neolithic. Insights from the variscite mines of Gavà (Barcelona)

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