One of the aims of the archaeometric study is to associate the pottery compositions with the materials in the surrounding area. One way of doing this is by comparing it with the analysis of the sediments or alteration materials. In this study we decided to use samples from the C horizon belonging to the Geochemical Atlas of Galicia (Guitián Ojea 1992) made available to us thanks to Dr. B Prieto Lamas from the Soil Science and Agricultural Chemistry Department of the Faculty of Pharmacy of the USC. To produce this atlas, samples were taken in the whole of Galicia every square kilometre in the C horizon of the alteration fronts. It was found that these materials were closer to the composition of the sources of raw materials than the unaltered rocks themselves (geological maps only show lithologies in their “raw” state, and not altered materials).
The aims of the work depending on those for which the material is finally selected are:
A) With the aim of comparing different types of sites and periods
-contextual variability (purpose of the sites: settlements, burials, etc.)
-diachronic variability (from prehistory to recent times)
B) With the aim of making an archaeometric characterisation of the movable material culture from each site
-existing amount of pottery
-morphological-functional variety of the pottery
C) With the aim of studying specific aspects of the pottery
-technology used for mixtures
-surface finishes and decorations
D) With the aim of highlighting the exceptional nature and importance of certain sites and pottery
-uniqueness of certain pottery and other objects
E) With the aim of being able to carry out different statistical studies
-minimum number of individuals and subgroups within the classification or category variables
F) With the aim of studying, verifying and contrasting different methodological aspects
-variability of composition depending on the part of the vessel chosen
-minimum amount of sample required in order to stabilise the average
-other criteria for refining certain techniques
G) Depending on the availability of access to the samples
The sites that are in the final stages of excavation or those for which reports are being written are the most suitable in terms of having access to the material.
H) With the aim of adapting to the progress of the research
During the stage of processing the information obtained, new working hypotheses arise that need to be confirmed or rejected. This means that on some occasions new samples may have to be incorporated.
The methodology used to study the pottery begins by systematising the archaeological research carried out. Based on the archaeology study of the pottery, a selection of samples is taken for analysis. A range of analytical techniques are used, as shown in the figure below.
One of the most important objectives is to reconstruct the manufacturing processes used for the pottery; by combining approaches from the fields of archaeology and archaeometry, we can almost completely reconstruct these processes. The second figure shown below shows in which manufacturing stages the techniques we apply can be of use.