Microstratigraphy and micro CT scanning

I came across these two studies in Journal of Archaeological Science recently, through Google citation alerts. It's always satisfying when my papers are cited, as it shows that there are people out there actually reading them and finding them useful! It's especially satisfying when the citing papers are as exciting as these! Both are by the same team, with lead author Hans Huisman who you may remember gave me some very useful advice through my Micrograph of the Month feature on some of my thin sections.

The first paper is "A question of scales: studying Neolithic subsistence using micro CT scanning of midden deposits" Here Husiman et al. apply micro CT scanning to thin section analysis. CT scan, or CAT scan, stands for computerised tomography, which uses a series of X rays to produce 3D images of components that are enclosed within a matrix. This is the same technique that is used in medical applications to look inside the body, but at a much smaller scale, hence the micro CT.

The application of this technique to thin section blocks is really exciting. One of the limitations of thin section slide analysis is that we are looking at a two dimensional version of deposits that are in fact three dimensional. By applying micro CT scanning, the authors have been able to provide 3D models of microscopic inclusions, within their precise depositional context. So we can see the nature of their deposition, in 3D! This is especially useful for materials such as small bone fragments and plant remains, which can be very difficult to identify if they are not at a favourable angle in the thin section slide. 

The authors conclude that this is a valuable addition to microstratigraphic studies, but not as a replacement. I think they are quite understated in the potential importance - this could be a new essential step to identify without ambiguity, the original structure of materials such as conjoined phytoliths, which break apart during laboratory extraction, but are difficult to identify in situ in thin section.With this technique we can do both - look at the specific context and number of conjoined cells, and also identify the species! 

The second paper is "Systematic cultivation of the Swifterbant wetlands (The Netherlands). Evidence from Neolithic tillage marks (c. 4300-4000 cal. BC)" and has some fantastic images of well preserved micro-laminated plant remains, that look very similar to deposits that we see in middens at Catalhoyuk. It is quite remarkable in some ways that these 2 sites, separated by time and geography, show such similar deposit types. It is very interesting from a methodological viewpoint, as it confirms that similar activities can produce similar microscopic traces, even when the depth of deposits is quite different. It also highlights how exceptional preservation, as is seen in buried deposits at Catalhoyuk, and here at the Swifterbant S4 site, can show us how much of the archaeologial record is missing from other sites.