Preservation of fossil seeds from a 10th century AD cess pit at Coppergate, York

Fossilization processes were investigated in terrestrial archaeological dep osits, focusing on the preservation of sub- fossil seeds from a 10th centur y cess pit at Coppergate in York. Flash pyrolysis-gas chromatography/mass s pectrometry (Py-GC/MS) revealed that the bulk of the assemblage comprises w ell-preserved organic remains, exemplified by blackberry (Rubus Fruticosus) endocarps which retain a near-pristine ligno-cellulose composition. Crab a pple (Malus sylvestris) pips are unique in combining an organic seed coast with an embryo which has been phosphatized. Endosperm tissue, nutrient sphe res in the cotyledons and, in one specimen, the cotyledon cell walls are re plicated in calcium phosphate. Casts of the sclerotic tests cells were also observed in one specimen. The crab apple seed coats have an unusual compos ition, interpreted as a tannin-cellulose complex. Precipitation of early di agenetic minerals among these organically preserved fossils appears to be r estricted to seeds with permeable coast through which ions were transported from pore waters.