Luminescence Research Laboratory

Prehistoric pottery from Britain

Introduction

A large amount of pottery from the 1st millennium BC in Britain is difficult to date since it is generally unremarkable. For example, in the East Midlands, the same styles and fabrics remained in use through many centuries. It is therefore difficult for archaeologists to construct sequences of the development of the pottery, with which new finds can be compared and dated. Even where such sequences have been constructed, the seuqences may be 'floating' with no fixed chronological markers.

An example of a sherd of decorated pottery - East Midlands Scored Ware from excavations at Crick, Northamptonshire. This style of pottery is thought to have been made throughout the 4th to 1st centuries BC, and possible earlier.

Direct scientific dating of the pottery can provide these markers, giving information on the rates of changes of styles and testing the validity of the pottery typologies..Unfortunately, there are difficulties in applying radiocarbon dating to this problem. Firstly it is rare to be able to date the pottery directly, for example by dating organic matter taken from the fabric of the pot or charcoal scraped from the surface of the pot. Ssecondly, radiocarbon ages need to be calibrated and the calibration curve has a flat spot in the 1st millennium BC; for example, calibrating a radiocarbon date of 2500 ± 80 BP gives a very wide range: 800-400 BC.

Luminescence dating, however, can be applied directly to the pottery since it makes use of energy stored in crystals within the pottery. More about the principles of luminescence dating can be found here.

Comparison of Luminescence Ages with Archaeological Ages

The majority of the sherds tested were unremarkable: coarse grained body sherds with no identifiable shape or decoration and therefore there was limited independent dating evidence. A small number, however, did have characteristic rim shapes or patterning and could be dated by comparison with pottery sequences for the area. Independent dates were also obtained for several of the body sherds by carbon dating of nearby organic material or typological dating of nearby diagnostic pottery.

Luminescence vs Archaeological Ages

Characteristics of the fabric of the pottery such as the coarseness, composition, colour (indicative of firing temperature) have also been used to provide dates for pottery in the absence of characteristc shapes and patterns or independent dating evidence. A comparison of the luminescence dates with 'fabric dates' shows some major inconsistencies, suggesting that use of fabric also is not a good indicator of the age.

A case study

Northamptonshire shell tempered pottery

It is generally accepted that the majority of the pottery in Northamptonshire in the Late Bronze Age and Early Iron Age was tempered with fine shell. Towards the Middle Iron Age, ironstone and, later, grog replaced shell as a temper. Coarser shell was again used as a temper in the Late Iron Age. The coarseness of the shell temper is therefore used to distinguish Early Iron Age and Late Iron Age pottery. Luminescence dates for shell tempered fabrics from three sites in Northamptonshire (Wollaston Quarry, Hardwater Road and Sywell) confirm that there are two distinct periods in which shell was used as a temper. Mean luminescence dates for each group are 260 BC ± 60 ± 140 and 780 BC ± 100 ± 180. However, fine and coarse shell fabrics are found in each chronological group, showing that the coarseness of the shell temper should not be used to date this pottery.

Khoi pottery from South Africa

Direct dating of potsherds found on the surface iin the Upper Karoo region of the Seacow Valley was investigated. Although conventional radiocarbon dates can be obtained from the fibre temper in most Later Stone Age pottery from this area, this does not apply to Khoi ware which contains insufficient carbon, nor to comb-stamp ware which is poor in fibre. Luminescence dates were obtained from a number of examples of Khoi and comb-stamped pot sherds. These are in good agreement with radiocarbon dates for associated fibre-tempered potsherds and for charcoal. These results are important since they provide independent dates for these styles of pottery and demonstrate that luminescence dating can be applied to surface pottery.

Sampson, C.G, Bailiff, I.K. and S.M. Barnett (1997) Thermoluminescence dates from later Stone Age pottery on surface sites in the Upper Karoo. South African Archaeological Bulletin 52 38-42.

University of Durham

Luminescence Laboratory

Dating pottery

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