Microfossil-determined provenance of clay building materials at Burrough Hill Iron Age hill fort, Leicestershire, England

The Iron Age hill fort at Burrough Hill, Leicestershire, eastern England, lies in a lowland landscape of Mesozoic sedimentary rocks comprising mudstones with thin limestone units, sandstones and ironstones, which are blanketed by Pleistocene till. During the late Iron Age the hill fort was an important central place; permanent occupation probably began in Early-Middle Iron Age and continued into the Roman period. A variety of materials in archaeological contexts from the site, including clay rampart bonding and the clay linings of storage pits and floors, are found to yield characteristically mixed microfossil assemblages of Early to Late Jurassic ostracods and foraminifera, together with foraminifera from the Late Cretaceous. These provide a unique microfossil signature that indicate provenance from the local till. Microfossils can also be recovered from Middle to Late Iron Age potsherds at Burrough Hill, and these too suggest a local glacial source for the clay. Our analysis demonstrates the power of microfossils to provenance clay materials used for construction and manufactures at an Iron Age site, where a detailed baseline understanding of the local geology is firmly established.