The well-known fact that the sources of evidence concerning the pre-Neolithic period are seriously incomplete has not yet been analysed sufficiently, being concealed by the intensive interaction of very complex and variable factors. It is obvious, though, that even an imperfect attempt to quantify this problem could contribute to an explanation of the causes for the striking differences between the volume of archaeological source material from adjacent territories, or show the limits of attempts at a historical interpretation of the interrelationships between pre-Neolithic cultures. Unlike the post-Mesolithic period, the sources of the pre-Neolithic foraging societies suffer from reduced field visibility:
1 first of all, they are not usually indicated by colour contrasts in the feature fillings;
2 as a rule, they are reduced only to residues made of the most resistant materials;
3 because of the mobility of small hunter-gatherer groups, only limited accumulations of finds occur in temporary camps, both in extent and in volume, easily escaping attention;
4 Palaeolithic finds lie deeper under the present-day surface and are discovered less frequently than the remains of later periods;
5 the Palaeolithic record was, over tens of thousands of years – this partly under the extreme Pleistocene conditions – subjected to destruction more frequently than the post-Palaeolithic romains;
6 the intensity of the sedimentary and denu-datory processes differs regionally, and in other ways.