Late Saxon to Early Medieval Salterns on Land North of Greenpark Avenue, King’s Lynn, Norfolk: PXA and UPD

Oxford Archaeology East (OA East) carried out an archaeological excavation between 4th February and 5th March 2019 at Land north of Greenpark Avenue, King’s Lynn, Norfolk. This work was commissioned by NPS Property Consultants Ltd. The site comprised 3.8ha of undeveloped land, within the urban reach of King’s Lynn, proposed for redevelopment as a primary school and associated grounds.
These works lie in a significant area of industrial archaeological remains relating to salt-making, during the later Anglo-Saxon and medieval periods. This industrial landscape is currently being investigated by OA as part of a wider scope of works for the adjacent Lynnsport residential development by Lovell Partnerships Ltd.
An initial phase of evaluation by OA East in February 2018, which incorporated a topographical survey of the site, uncovered mounds associated with salt-making at six locations: Salterns 1, 4-8. Two of these salterns (Salterns 5 and 8) were mapped on the NHER (NHER 27909 and 27907 respectively). A further two (Salterns 1 and 4) extended beyond the southern boundary of the site where they were previously excavated by OA East in 2017 as part of the Lynnsport 4 and 5 developments (Clarke 2017b). As well as revealing waste deposits from the salt-making process constituting the mounds, the evaluation also revealed the remains of broken-up brine boiling hearths and in-situ remains of clay-lined tanks.
The current excavation investigated Salterns 4-6 which were located in areas that were to be impacted upon at depth by the proposed development. Significantly, within the lower sequence of deposits excavated in Saltern 5, a burnt layer of material produced fragments of both salt slag cakes and fired clay brick supports for lead pans; diagnostic artefacts associated with brine boiling hearths. Equally significantly, a large number of salt-making features were uncovered within the upper part of Saltern 5, which included an in-situ brine boiling hearth and surviving elements of filtration units for concentrated brine production. Near to the hearth lay a spread of burnt material which overlay a rake-out pit, evidently excavated to store the hearth’s waste. Two heavily truncated clay-lined pits were also revealed in Saltern 4. These features and their waste products provided three radiocarbon dates, an archaeomagnetic date and four sherds of pottery to provide a dating framework which suggests salt-making was carried out on this site between the 10th and 12th centuries.
The excavation of Saltern 5 also uncovered parts of the circuits of two heavily truncated curvilinear gullies that probably represent drainage channels for hayricks (Riley circles) dating from the early modern period.