Tracing Celtic Civilisation with Neutrons

About 7500 years ago, men in Europe began to form earth with their hands into pots and created ceramics by firing them. Only since the 5th century B.C. the potteri´s wheel was introduced and making pottery became easier. Wheelturned pottery could be produced quickly and in large amounts. Handicrafts were established as independent professions in the big Celtic towns during the 3rd to the 1st century B.C. Objects for daily use were produced in abundance. They were sold, and an extended system of trade and economy developed. Therefore the civilization of this period was very uniform.

Certain forms of jewelry and ceramics were found all over Europe (Fig. 1). This oppida civilization can be considered as a first European Economical Union reaching from the south of Gallia to Bohemia in the East. Its formation and its inner organisation are so far little understood by archaeology. A study of its structures would be the key to an assessment of the Celtic civilisation, which determined the history of middle and Western Europe in the last two centuries B.C. (Fig. 2 and 3).

A characterization of the trade regions by a careful study of the amount and regional spread of traded goods would help in such an attempt. Of all finds ceramics is the most promising ware for such a study. It is abundant everywhere and its provenance can be determined.

The archaeologist uses the help of science to determine the origin of ceramics. The provenance of ceramics, or better of the clay it is made of, can be exactly localized. Different clay deposits exhibit characteristic trace element patterns, and pottery made from that clay carries its trace element distribution as a fingerprint. The trace element contents are determined by neutron activation analysis, the most accurate method of trace element analysis.

Small samples of sherds are ground in a mortar for analysis. The powder is refired to remove moisture and carbonate and sealed into quartz ampoules. During a short irradiation with neutrons in the core of a nuclear reactor artificial radioactivity is produced. A standard with known composition is irradiated together with the samples. Comparing the radioactive radiation emitted by the samples with that in the standard, allows to determine compositions of the samples. Data gained in such a way are sorted into groups by statistical methods. As a result one finds groups of sherds made from identical raw materials.

Our study of Celtic ceramics started at the central oppidum of Manching, north of Munich. This settlement covered an area of 380 hectares and was one of the largest towns in Celtic times. Its region of economic influence can be determined by comparing pottery which was made in Manching with the material from rural and urban settlements in the close and more distant vicinity.

First results show that the wide distribution of pottery of similar appearance in Celtic Central Europe is due to the transfer of information on form and decorations and on production techniques, while the actual migration of ceramics was an unimportant exception. Pieces of painted and wheelturned ware, undistinguishable by appearance, were produced in different local pottery centers, Manching being just one of them. Technology transfer was already of crucial importance in Celtic Europe.

Additional analyses will help to gain a more and more comprehensive picture. It is already clear, however, that the application of modern techniques is essential in the study of prehistory. In this example the use of neutrons in a research reactor reveals interesting facts about the world from which we come.