Visualising lithic use wear traces – photo stacking

It is not always immediately apparent to non-specialists what we – use wear analysts – do and see and how we can be certain of our observations. This is partially due to the imagery many use wear analysts produce. In a recent paper A. van Gijn (2013) reflects on the current state of the field of lithic microwear or use-wear analysis and points out a number of aspects of our work in which improvements are possible or even necessary. These, in my opinion rightly, include an increase in sample sizes (e.g. by scanning tools with a stereomicroscope before moving on to higher magnifications); more incorporation of ethnographic data; a standardisation of practise and nomenclature; embedding the use wear traces in the cultural biographies of artefacts and providing better quality imagery.

The basal end of a Mesolithic scraper from Arconciel/La Souche, Switzerland (quartzit au grain fin/Ölquarzit). Left a normal photo. Right a composite photo of the same part of the artefact. Taken with a Keyence Digital Microscope.

The basal end of a Mesolithic scraper from Arconciel/La Souche, Switzerland (quartzit au grain fin/Ölquarzit). Left a normal photo. Right a composite photo of the same part of the artefact. Taken with a Keyence Digital Microscope.

The last point can be achieved by photo-stacking through the use of specialist software or microscopes, such as the digital microscope I use, which are able to make composite photos. The image above shows what photo stacking or composite photos allows you to do.

One major drawback of the microwear approach is the lack of convincing visual evidence. The pictures generally shown at meetings are fuzzy and lack depth of field. Usually only a small part of the photograph is sharp, namely the spot of polish we want to address. Although insiders may usually see and recognize what is being discussed, it is little wonder that the general audience has no idea what it has to look at and remains rather skeptical. There is much to gain from improving the visualization of the microwear traces. – A. L. van Gijn (2013 – p. 3)

Typically, it is difficult to make microscopic photos of larger parts of artefacts that are in focus. Photo stacking, however, allows exactly this: an increased depth of field with much larger parts of the artefact shown in focus. This way not only the traces, but also their contexts can be visualised. I find this technique does not work very well in all situations or for all raw-materials or for all traces. Nonetheless, it makes our work more effective and it will surely allow us to communicate our methodology and findings much better not only to fellow specialists, but also to non-use wear specialist archaeologists and the general public.

ResearchBlogging.org

Gijn, van A. (2013). Science and interpretation in microwear studies, Journal of Archaeological Science, DOI:

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