Importance of Field Work: Sifting to Recover Bones

Continuing with our theme of focusing on excavation and field work in mortuary archaeology, let’s look at another important step of the process: sifting.

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MSU Campus Archaeology Program sifting dirt during a survey

While the excavation is progressing, the process of sifting the recovered dirt is occurring at the same time. Sifting dirt is one of the activities that occurs on almost every archaeological site, whether a large scale excavation or small scale study of the insides of cremation urns. The process involves putting all soil recovered from the excavation through a mesh wire screen. It improves the recovery rate of small artifacts and is an important step in archaeology.

A new article by Mays, Vincent and Campbell (2012) explores the current process of sifting at mortuary sites and re-assesses the practice. Sieving the soil below the burial, while suggested, is often overlooked. The authors note, “there is a dearth of empirical studies of recovery of human remains from archaeological sites which measure the effectiveness of over hand retrieval, or which compare the merits of using sieves of different mesh sizes”. The goal of their study is to fill this gap and provide empirical data on the value of sieving, primarily in poorly preserved inhumation burials and loose teeth. They also assess the differences between hand collection and sieving, and the different size mesh screens.

The study was conducted during the excavations at the cemetery site of Whitby from 1999-2000. The cemetery was in use from the 7th to 9th century CE. The burials lacked grave goods, but the presence of nails suggested that some of the individuals were interred in coffins. Preservation at the site was fairly poor and wood survived due to the clay underlying the soil. This also caused poor preservation of the human remains; 325 graves were excavated but only 225 preserved any skeletal material. All the remains recovered were highly fragmented. The process for the sieving experiment involved removal of all grave fill by trowel to expose the skeleton. The burial was recorded and photographed, and then the exposed remains were removed by hand. Any soil remaining in the grave was then recovered in three samples for sieving and floatation. Sample A corresponded to the head area of the grave, sample B to the torso and sample C to the legs/feet area. All soil was wet sieved, a process involving gently washing the sieve and soil with water through a stack of sieves of decreasing mesh size (8mm, 4mm, and 2mm). Screens of 8 and 4mm were handpicked through for human remains, and 2mm was scanned. The samples found in the sieve were weighed separately in order to determine the success of the process, and they were scored by reliability of identifying the portions of bone (i.e. cranial versus axial versus dental).

Of the 70 burials that underwent this process, in 62 dental elements were found in the screening process and in 51 there were identifiable skeletal elements. Skull fragments were identified in 43 burials, 34 had fragments of long bones and 15 had fragments of other identifiable skeletal elements. Of the 62 burials with dental remains, a total of 946 permanent teeth were found, of which 913 (97%) were recovered during the sieving process. Overall, sieving increased the weight of the recovered human remains by 53% more than traditional hand collection alone. While studying human remains is important, we need to remember that this is completely reliant on our ability to remove as much of the skeleton from the grave as possible, collecting all available evidence. This study demonstrates that meticulous removal of small elements, such as dentition, can result in a substantial increase in material available for study.

These two articles highlight the correlation between the material collected in the field to the interpretation of human remains and burial sites. Careful record keeping about broader context of the burial and attention to the collection of all possible remains might provide unexpected opportunities to reduce bias. Improved methods in the field will lead to increased data and better interpretations in the lab.

Hope everyone out there has a safe and productive field season!

Works Cited

ResearchBlogging.org Mays, S., Vincent, S., & Campbell, G. (2012). The value of sieving of grave soil in the recovery of human remains: an experimental study of poorly preserved archaeological inhumations Journal of Archaeological Science, 39 (10), 3248-3254 DOI: 10.1016/j.jas.2012.05.006

 

[Portions of this are reprinted from the Society for Archaeological Science Bulletin 36(2), Summer 2013. See the full bulletin issue here]

7 responses to “Importance of Field Work: Sifting to Recover Bones

  1. It seems so crazy that during the reign of the antiquarians the techniques involved in excavation really didn’t exist at all. You would have figured that anyone who was looking to go grave robbing would at least try to comb the entire area for jewelry and other worthwhile artifacts.

  2. Hey, Katy! Thanks for sharing this with us! I didn’t know that sifting screens could be used to recover bones in the dirt—that’s super neat! I realized, in your biography, that you’re an anthropology PhD student. How much longer do you have in your current program?

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