NHER 68894 (Monument record) - Medieval salterns and associated remains

May 2021. Desk-based Assessment.
Assessment of potential impact of proposed development.
See report (S1) for further details.
P. Watkins (HES), 27 January 2025.

May and August 2021. Geophysical Survey.
Magnetometer survey of part of large proposed development area (F4).
The results of this survey were potentially impaired by the presence of 'green waste' across the entire site, which created a dense, continuous spread of magnetic disturbance that may have masked archaeologically-significant anomalies.
Four clusters of high magnitude anomalies identified in the northernmost part of the site potentially represent remains associated with medieval or earlier salt production. Although these anomalies are some distance from any of the previously recorded possible saltern mounds, they do correspond with areas of slightly elevated ground seen on visualised LiDAR data of the site (reproduced in the report on the subsequent trial trenching). These responses are though not necessarily archaeological in origin and it is noted that one group at TF 6275 2260 potentially relates to the installation and/or repair of an adjacent sluice shown on the Ordnance Survey First Edition Six-inch map (S2). Two other groups of anomalies are also close to a former pond shown on the same map at TF 6276 2248.
Various linear trends potentially represent former watercourses and/or natural variation in the natural alluvial deposits. As at the sites to the north and west these responses are bounded to the west by a faint north-to-south aligned trend. This may represent a geological boundary such as a former shoreline but does not correspond with the line of any of the known former sea defences.
There is some limited correlation between the linear responses recorded and features shown on (S2) but no obvious trace of surviving remains associated with either line of the Old East Sea Bank (NHER 5528) or the possible saltern mounds recorded in the south-east part of the site (NHER 27926). The visualised LiDAR data for the site does though suggest that both the sea bank and the possible saltern mounds as associated with surviving low earthworks.
Information from draft report. Final version awaited.
P. Watkins (HES), 27 January 2025.

September-October 2023. Trial Trenching.
Evaluation of part of large proposed development site (Trenches 21-35).
The 15 trenches excavated revealed clear evidence for medieval salt production at this location. The remains uncovered relate to an industry that would have seen salt collected by boiling a concentrated brine solution generated by washing and filtering salt-impregnated silts and sand extracted from the nearby saltmarsh. The various saltern mounds recorded in the area represent large accumulates of the waste silt generated by this process.
A number of the trenches were placed to coincide with a group of probable saltern mounds in the southern half of the site that are visible as earthworks on aerial photographs (NHER 27926). The largest mound was shown to be comprised of light yellow-brown silts, with the presence of occasional charcoal flecks and fragments of scorched silt serving to confirm that this material represented waste from salt production. The mound material survived to a depth of up to 0.7m. Significantly, two of the trenches encountered features that had almost certainly been associated with salt production, including a partially exposed hearth or hearth rake-out pit. This was partly overlain by probable filtration waste and consisted of a sub-circular feature with a partially scorched base and a fill containing heat-reddened silt and dumps of salt slag. A sample from this deposit contained frequent charcoal as well as marine shell, ceramic building material, slag, fired clay and animal bone. Three clay-lined pits interpreted as brine filtration tanks were also recorded. A sample from the fill of one of these pits contained charcoal, frequent freshwater molluscs and abundant ostracods.
Several of the trenches dug in the northern half of the site were placed to investigate two of the clusters of potentially archaeologically-significant anomalies identified by the preceding geophysical survey, which coincided with areas of raised ground visible in the visualised LiDAR data for the site. This work confirmed that, as suspected, these were the remains of previously unidentified saltern mounds - with all five of the trenches in this area encountering material likely to represent accumulations of filtration waste. A number of features associated with salt production were also recorded. These included a small, square, clay-lined probable filtration tank in the westernmost trench that was cut into a raised deposit of light yellowish-brown silt likely to represent the western side of the Old East Sea Bank (NHER 5528). This is of particular interest as this bank had been thought to post-date the salterns lying to its east. Features recorded to the east of the sea bank included three probable hearth rake-out pits that coincided with the anomalies recorded by the geophysical survey. These contained dumps of salt slag, fragments of burnt clay, burnt flints and pieces of burnt stone. Samples produced a similar mix of charcoal and industrial waste seen in the fill of the similar feature recorded to the south. A pit containing ashy material was also identified. The majority of these remains were overlain by deposits of waste material from salt production, demonstrating that activity had continued in the vicinity after these particular features had fallen out of use. Fours sherds of medieval pottery within one of the rake-out pits represented the only dating evidence recovered. A medieval date is though likely for all of the salterns uncovered at this site, given their position at the western, seawards edge of the group.
The two westernmost trenches were positioned to coincide with a former channel or watercourse shown on the Ordnance Survey First Edition Six-inch map (S2). These revealed little of interest, with only a range of sterile silt deposits recorded.
Information from draft report. Final version awaited.
P. Watkins (HES), 27 January 2025.