Methodologies for assessment of the state of preservation of pollen and plant macrofossil remains in waterlogged deposits

Methodologies are proposed for assessing the state of preservation of pollen and plant macrofossil remains based on the investigation of known prehistoric waterlogged sites in the Somerset Levels, under threat from peat extraction and peat wastage. For each sample assessed, a fixed number of pollen grains and macrofossil seeds was classified according to deterioration type and scored for intensity of deterioration. The principal deterioration types recognised for pollen were biochemical (corrosion and degradation) and mechanical (breakage and crumpling). For seeds two main categories of deterioration were adopted, fragmentation and erosion/corrosion of the seed testa. The calculation of preservation indices for pollen and macrofossils allowed comparisons to be made within and between sites. A range of factors which may have influenced variations in preservation are briefly discussed. These methodologies are potentially valuable where there is a need to assess the survival of the archaeobotanical record, particularly where sites are sensitive to environmental change.