3.3 The use of guide artefacts for dating surface scatters

In the core regions surface sites have been registered almost exclusively. For dating such site assemblages, we depend on typochronological dating. Typo-chronology has long been a useful method of dating in archaeology. For the area under investigation, however, the lack of a uniform terminology and cultural attribution of the artefacts is a problem. On the other hand the limited dating accuracy of flint and pottery in surface scatters is a serious limitation in dating the surface sites.

There are a number of typo-chronological diagrams for flint artefacts (Arts 1987; Fiedler 1979; Löhr 1971, 1974, 1977; Newell 1973) and pottery (Louwe Kooijmans 1976; 1980; Lüning 1967; Modderman 1970). These diagrams are based both on excavated and surface finds and provide an excellent illustration of the problems outlined above. First of all there are relatively large differences between the several schemes regarding the various cultural phases, the artefact typology and the cultural attribution of the artefact types. Secondly, hardly any artefact type occurs exclusively in a single archaeological phase. Certain artefacts occur with a similar frequency in several phases, whereas other artefacts have a clear peak. The latter are more suitable as cultural 'markers' than those artefacts with a more continuous presence.

Based on the largest common denominator and taking into account the position of the Meuse Valley vis-a-vis the areas studied for the chrono-typological diagrams mentioned before, we have defined 10 cultural phases for the Meuse Valley Project, of which the two Beaker phases are often combined. For each phase the chronologically most characteristic (guide) artefacts have been selected. The number considered to be guide artefacts has been limited to 28 types. All other artefact types are too indistinct typologically and/or not specific enough chronologically to be used as a means of dating.

Two remarks should be made here about the typo-chronological dating method selected and the guide artefacts defined:

1. In dating site assemblages the associated presence of several artefacts is often considered, or the relative frequency of various artefact types. A site assemblage is dated to the LBK phase when both asymmetrical hollow-base points, adzes and straight-end scrapers on short blades occur. The early Mesolithic is characterized by a high percentage of microliths (ABCD-points and triangles) and low percentages of points with surface retouch, whereas that ratio is exactly reversed for the middle Mesolithic. However, the lack of certainty about the find association is the main characteristic of surface finds. A combination of (guide) artefacts on a single site does not by itself mean one habitation phase, which is why we have made a decision in favour of individual guide artefacts.
2. By using guide artefacts with a peak in use, the 'centre of chronological gravity' (Wansleeben 1987), a certain error is introduced. For example the macrolithic artefacts are most numerous in the Michelsberg culture, but they also occur sometimes in the Rössen and Vlaardingen/Stein phases and even occasionally in an LBK or Beaker context. The result of this situation is that too many sites may be dated to a single phase. However, as long as the centre of chronological gravity is large enough, the margin of error introduced in this way is acceptable to us. Macrolithic artefacts are most numerous in the Michelsberg phase and therefore the general trend in the distribution map of such artefacts will reflect most strongly the habitation activities of this phase.