Burnt Bones (The process and method of excavating cremation vessels)February 1, 2011 About my museum job, Archaeology, Blogs, Centre for Human Bioarchaeology, Conservation, MOLA Osteology
S. Matthews, BA, MSc
This month Sarah Matthews talks about the process of excavating human remains from cremation vessels. Click on the images to see further details of the excavation.
Archaeological investigations in 2010 by the Museum of London Archaeology revealed a number of Roman cremation vessels from a site in Surrey. While many of the vessels had been badly damaged by ploughing, 10 remained intact enough for further study.
The purpose of excavating cremation vessels is to ascertain how efficient the cremation process was, determine the distribution of bone in the vessel, gather knowledge about the pyre, and information about the individual cremated (age, sex and any pathological bone changes) skeleton (McKinley, 2004).
The excavation is carried out by carefully removing the soil from the vessel in spits (2-3cm layers). To begin, a piece of string is placed horizontally across the bucket dividing the vessel into two halves. One half is then excavated carefully and delicately by removing the soil and leaving the bone in place. To do this a variety of small trowels, wooden skewers and small brushes are used. This takes a great deal of patience, even the slightest knock to the bone can cause it to fragment. A plan and section is then drawn before excavating the other half.
The first spit (Picture 2) often contains very little bone, the overall the density of bone increases at the bottom of the vessel. After removing both halves of the spit, any bone uncovered is left in situ, photographed and planned.
Picture 2 (Pot B): Top of Spit two
Picture 3 (Pot B): top of Spit Three
Picture 3 shows the bone excavated from spit two revealing a dense quantity of bone. The majority of this bone comprises fragments of long bones, these often fracture in crescent or ‘U shapes’ (McKinley, 2004) running along the shaft. To the lower left corner of the urn a large, flat piece of bone has just been uncovered but is so far unidentified. Due to the density and overlapping nature of cremations often several pieces of bone need to be removed before elements can be uncovered enough to be identified.
Picture 4 (Pot B): Top of Spit Four
As the excavation continues, the anatomical features of the bone become apparent and the large fragment in the lower left can now be identified as part of a pelvis. Spits are not always easy to keep to an approximate depth and there maybe variations in the depth across the pot. In the centre (Picture 4) the depth could only able to be taken down by 1.5cms due to a large patch of trabecular bone lying just below the surface. It is sometimes necessary to leave soil in place rather than risking destroying the bone.
Picture 5 (Pot B): Top of spit five
Towards the bottom of the pot large pieces of identifiable bone are present. The right side of the pelvis can be seen in Picture 5 with the auricular surface facing towards the centre. Each element is measured, photographed and planned in case it disintegrates further during lifting. Any colour variation is recorded as this may suggest temperature deviations during the cremation. Large identifiable elements are bagged separately with the context and spit numbers marked on the bag.
Picture 6 (Pot A): Large areas of skull.
Picture six shows the importance of correct planning and excavation. Burning of the bone and shrinkage due to dehydration produces microfractures, these can result in the bone fragmenting during excavation and recovery (McKinley, 2004). The two large areas of skull can be seen in situ and once planned it is possible to tell that a very large piece of skull remained after burning.
The most important aspect of excavating cremations is to gain as much information as possible about the bone, the colour and disposition and any finds discovered inside the vessel. Once the bone is washed and dried, further analysis can be carried out to gain further evidence about the individual inside. This helps our understanding of the ritual and processes regarding cremated remains from the past.
For further information see..
Brickley, M. and McKinley, J. 2004. Guidelines to the standard for recording human remains IFA/ BABAO.