The provenance of Chalk Tesserae from selected sites in Roman Britain

Microfossil analysis of chalk tesserae from mosaics at five sites in Roman Britain (Caerleon, Colchester, the Isle of Wight, Leicester and London) was undertaken in order to ascertain the biostratigraphical age of the chalk used and thereby to determine its lithostratigraphical position within the Chalk Group. This information was then used to determine its most likely geographical provenance. The foraminiferal evidence presented in this thesis strongly suggests that the source of the chalk used to manufacture the tesserae within the Roman province varied with time. Comparison of the results obtained with previous micropalaeontological analyses of chalk tesserae from Silchester, Norden (Dorset) and elsewhere in London suggest that Dorset may have acted as a regional source of chalk tesserae supply for mosaics dating to the first or early second century AD. This confirms previous suggestions that a ‘geomaterials complex’ was operating in the Poole-Purbeck area of south-east Dorset at this time. Chalk tesserae dating to later periods did not display this same pattern of supply and appear to have been derived from elsewhere in the province. Kent and Sussex are suggested as possible sources for chalk tesserae dating to the second and third centuries AD, whereas Baldock in Hertfordshire emerges as a possible source in the fourth. The geological evidence also shows that harder members of the Chalk Group do not seem to have been preferentially selected for use in tesserae manufacture. The results obtained confirm the value of the ‘microfossil approach’ to the problem of provenance in archaeological studies. It is suggested that the extension of this technique to chalk tesserae from other sites might enable some wider aspects of mosaic manufacture in Roman Britain to be investigated and two areas are put forward for future consideration.