Site Event/Activity record ECH6482 - Heronbridge, Chester, Cheshire: Environmental Analysis

Following on from an archaeological excavation in 2004/5 by Chester Archaeological Society (see ECH4326), at the multi-period scheduled monument at Heronbridge, environmental assessment of collected samples was undertaken by Oxford Archaeology North. The samples were taken from a section of ditch, defining a curvilinear enclosure, which overlies part of the Roman settlement; the ditch appears to have been later used as an ad hoc retting pit. Some 84 pieces of wood were examined, together with four bulk samples and a series of four monolith samples. The results from the environmental assessment demonstrated excellent preservation on waterlogged plant remains. Six species of wood were identified (alder, ash, birch, hazel, slalicaceae, prunus), with hazel predominant. Most pieces were between 2 and 7 years of age, and 20 pieces showed evidence of working in the form of diagonally cut ends. The data indicates that coppicing of the trees was occurring. The analysis of the waterlogged plant remains from the defensive ditch observed a very high frequency of flax seeds and capsule fragments, together with abundant short sections of plant stems, likely from flax. Other than the flax seeds, seeds from plants of cultivated (corn chamomile, corn spurrey and wild radish) and open or waste ground (mallow, nettle, knotgrass) dominated the assemblage. Seeds indicative of grassland were also identified. The identification of the type and quantity of flax seeds, capsules and stems suggests that the ditch was being used to rett the stems for fibres. Also, the large numbers of nettle seeds and nettle pollen indicate that these too were being processed, the stems being a valuable source for fine fibres. Four monolith samples were taken for the purposes of assessment of pollen. Each was divided into eight sub-samples taken at known depths. The pollen assemblage was dominated throughout by grass, but supplemented with other herbaceous plants, some indicating cultivated or waste ground, others indicative of grassland, suggesting an open landscape with some hazel and alder woodland. Two radiocarbon dates were obtained from flax seeds; one cal AD 650-830, the other cal AD 760-980, and together giving an average date of AD 680-890. (1)