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D'ERRICO, D. - Glossy tools innovations in the method of interpretations of use-wear produced by plant processing

AUTHORS

Davide D'Errico

CATEGORY

Report

LANGUAGE

English

ABSTRACT

There is an emergent scholarly interest in the use of optical metallurgical microscopes to rercognise and define morphological features of wear traces produced by plant processing on stone tools.  Plant processing experiments have helped identify specific characteristics of micro-wear resulting from cutting different types of plants (Gassin 1993, Jensen 1994, Van Gjin 2010). The author of this thesis carried out analyses on wear traces produced by siliceous plants (Poaceae), reeds and other herbaceous plants, focusing specifically on the glossy produced by a specific plant (Clemente and Gibaja 1998, Ibanez et al. 2008, Jensen 1994, Van Gjin 2010).

Experimental data were compared to find out existing differences and to recognize wear traces on the archaeological material. The morphological features considered for defining a specific a trace are usually texture, topography, brightness and weave. The way these features combine defines a specific wear linked to a specific activity. It is important to notice that in an archaeological environment difficulties in reading may often occur, due mainly to the conservation status of the lithic instruments. Poorly developed traces can lead to inaccurate assignments because the characteristics, if not fully developed and recognized, may lead to several different interpretations.

I recently carried out experimental research to analyse a wide range of possible wear traces caused by cutting of plants (D'Errico 2011). I considered wear caused by both domestic and wild cereals, reeds, siliceous grasses and wooden plants to identify patterns related to the exploitation of different types of plants over different periods of time.

I made comparisons between the wear produced by such activities on modern reproductions of lithic instruments and archaeological materials coming from the Neolithic contexts of Masseria Candelaro (Puglia, Italy) and Çayönü (Anatolia, Turkey). In the following paragraphs I explain the methods adopted and show the results of this research.

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RESEARCH METHODS

Several flint instruments were produced to test wear after different periods of specific activity, from six to two hours. I considered the development of the wear in the following different areas of the tool:

- Margin area (outermost zone and more in contact with the worked material) 

- Retro margin area (intermediate zone, strictly close to the margin)

- Inner area (innermost area of the surface)

This topographic categorisation allows detecting variations in the distribution of use-wear within three specific areas, with particular characteristics related to the worked material and the time of use. 

The effectiveness of this method of investigation is especially evident in comparing wear traces in their early stage of development.  In particular, the retro margin area shows only a light polish in the early stages of formation. I introduced the term tending (for example ->smooth o ->flat) to indicate a stage where the polish does not present both a fully developed texture and topography, but tends towards a specific morphology.

dsc_0069

Fig. 1 - Cutting activites 1/2.

 

dsc_0010

Fig. 2 - Cutting activities 2/2.

 

RESULTS OF THE ANALYSIS

Tools used for cutting reeds (Phragmites australis) for over two hours (Tab. 1, Figs. 3 and 4) show a band of little developed polish in the marginal area of the edge. By moving slightly to the inside area, this band disappears and develops a particular polishing ->smooth present only on high points of the surface displaying a grill pattern weave. On the other hand the inner area is affected only by a widespread brightness, while no particular changes can be noticed on the surface.

Time

Band of polish

Margin Area

Retro Margin Area

Inner Area

2 hours

0.5mm

Edge slightly rounded. High point of the surface are smooth while the polish is localized in the lower parts

Grill pattern weave with ->smooth features in the immediate retro margin area

Presence of diffused brightness without relevant changes of the surface

 

Tab. 1 - Description of development of polish by reeds (2h) in three different areas of the surface. 

    

             

Fig. 3 - Experimental trace reed 2h margin area 10x.

2

Fig. 4 - Experimental trace reed 2h retro margin area 10x.

 

After five hours of use there is an accentuation of polish features in the margin area that presents itself still as ->smooth and ->flat with a much more tightened weave, while in the inner margin area a grill pattern weave is still present with a smoothing of the high points affecting also the lower areas (Tab. 2, Figs. 5 and 6). In the inner area only a diffused brightness can be noted.

 

Time

Band of polish

Margin Area

Retro Margin Area

Inner Area

5 hours

1.06mm

Polishing has more pronunced smooth and flat characteristics

Grill pattern weave with smooth features that interest retro margin area and lower zones

Presence of diffused brightness without relevant changes of the surface

 

Tab. 2 - Description of development of polish by reeds (5h) in three different areas of the surface. 

   

3                      

Fig. 5 - Experimental trace reed 5h margin area 10x.

 

 

Fig. 6 - Experimental trace reed 5h retro margin area 10x.

 

After six hours of use (Tab. 3, Figs. 7 and 8), the wear looks highly developed in the margin area, presenting a smooth texture with accentuated characteristics, but it is still not a compact and continuous band of polish, as the one produced by processing cereals. In the retro margin area the presence of grill pattern weave with rounded high points remains constant  and the lower parts of the surface appear only slightly affected by the polish, while in the inner area a slight rounding of the high points as well as a diffused brightness emerge.

 

Time

Band of polish

Margin Area

Retro Margin Area

Inner Area

6 hours

1.06mm

Compact band of polish, with smooth and flat characteristics strongly marked with heavy edge rounding

Grill pattern weave with smooth features on high points, marginal on lower zones

Presence of diffused brightness with minimal rounding of the highest points of the surface

 

Tab. 3 - Description of development of polish by reeds (6h) in three different areas of the surface.

 

5              

Fig. 7 - Experimental trace reed 6h margin area 10x.

 

6

Fig. 8 - Experimental trace reed 6h retro margin area 10x.

 

The main feature of the polish caused by cutting reeds is thus the smoothing of both the margin area and the retro margin area which are easily distinguishable from the remaining surface which instead appears rough.

Cereal processing wear look different indeed. It shows smoother and flatter features with a tighter weave than the one produced by reeds processing (Tab. 4, Figs. 9 and 10).  Although a compact and continuous band of polish is absent in both cases, the polish related to cereals is different for it affects also both the immediate and retro margin area.

Differences between reeds and siliceous plant processing can be summarized as follows:  

1. After six hours of use, polish due to siliceous grasses shows smoother and flatter characteristics and a tighter weave if compared with the one due to processing reeds.

2. Trace of reeds processing is always more present on the high points of the surface in the margin area and degrades more quickly in the retro margin area, while siliceous plants processing affects less internal areas of the surface.

An important result of the study is related to the distinction between wild and domestic cereals processing wear. Wild cereal processing produces a similar texture of polish only in the margin area, and differs from domestic cereal processing for the presence in the retro margin area of a slight rounding of the high points of the surface. Besides, traces left by wild cereals usually show a less developed polish. Such a difference could be caused by the different quantity of water present in the stem of wild and domestic cereals. The formers, did not have a constant supply of water and are more prone to stress caused by aridity (Celant and Lemorini p. c.), while the latter had more frequent access to water.

 

 

Weave

Edge rounding

Trace distribution

Texture/topography

Notes

Reeds

After 2h: half tigh

After 6h: tight

Maximum rounding: Medium

Experimental trace is  more present on the high points close to the edge.

retro margin area:smooth

Quite similar to  siliceous grasses but in general is more domed

After 6h: slight band of polish on  the edge

Siliceous grasses

After 1h: open

After  6h: compact

Edge rounding after 1h: Light

Maximum rounding: Heavy

Experimental trace is more present in the retro margin area and inner area than reeds.

Smoother and flatter than reeds

After 1h: no reflective band

After 6h: highly reflective band of polish

Cereals

After 1h30m: tight

Edge rounding after 1h30m: Medium

Experimental trace is much more intrusive than reeds. The trace not affected only the margin area.

Smoother and flatter than reeds and siliceous grasses

After 1h30m: slight band of polish, quite bright

 

Tab. 4 - Comparison between polish due to the cutting of reeds, grasses and cereals.   

 

7

Fig. 9 - Experimental trace wild cereals.

 

8

Fig. 10 - Wild cereals trace from Çayönü.

 

CONCLUSIONS

The study of the distribution of micro-wear on different areas of the surface of lithic instruments reveals important differences in the past use of plants and specific behavioural patterns related to them. To improve and test this method of investigation, further tests are required in order to recognise wear behaviour on a diachronic dimension, taking into consideration a large sample of plants that could have been exploited in specific areas in different periods. This approach in some cases could lead to the identification of both the processed materials and the tool's duration of usel. This would be essential for the reconstruction of patterns related to the exploitation of plant resources.

 

REFERENCES

Clemente, I. and Gibaja, J.F. (1998) Working processes on cereals: an approach through microwear analysis. Journal of Archaeological Science, 25, 457–464. 

D’Errico, D. (2011) Uomini, agricoltura e sperimentazione. Scelte culturali e sfruttamento dei vegetali nel Neolitico. Dissertation Archive Series, 11, available at the address http://www.archaeologicaltraces.org/index.php/2014-01-28-09-56-01/dissertations-archive/24-da0011

Gassin, B. (1993) Approche fonctionnelle des Industries lithiques du Néolithique provençal. L'exemple du site chasséen de la grotte de l'Eglise supérieure. Nanterre Edition Paris X University.

Ibanez, J. J., Clemente, I., Gassin, B., Gibaja, J. F., Gonzalez, J. E., Marquez, B., Philibert, S. and Rodriguez, A.(2008) Harvesting technology during the Neolithic in South-West Europe. In: Longo, L. and Skakun, N. (eds.) Prehistoric Technology 40 Years Later: Functional Studies and the Russian Legacy. British Archaeological Reports International Series, 1783. Oxford: Archaeopress, 183-196.

Jensen, H. J. (1994) Flint Tools and Plant Working: Hidden Traces of Stone Age Technology. Aarhus University Press.

Van Gjin, A.L. (2010) Flint in Focus. Lithic Biographies in the Neolithic and Bronze Age. Leiden: Sidestone Press.