Testing of the consistency of the sieving (wash-over) process of waterlogged sediments by multiple operators

The sieving process has a considerable influence on the later retrieved archaeobotanical data. As known from earlier works the wash-over method is the most suitable method to extract plant macroremains from waterlogged sediments. In this paper, it was tested by an experiment if different sievers using this method produced comparable results. Even with identical instructions, some differences between sievers were found in the larger fractions ≥2mm, namely the varying presence of small remains. We propose guidelines for counting remains so that this problem can be avoided. In the small fraction <0,35mm, differences were not that substantial anymore. In addition to differences caused by the sieving technique we could also show that the patchy pattern of clumpy waterlogged sediments complicates a statistically relevant subsampling. All in all, we can state, that only large differences between samples should be interpreted in palaeoeconomic terms. It is our purpose to raise awareness of the fact that the methodology has a strong impact on the results obtained and should therefore always be revealed on a detailed level, especially if data from one site will later be used for comparisons with other sites.