Reasons for Designation
Salt has been produced from sea water or, in inland areas, from brine springs
since before Roman times, and the technology used in the medieval period
displays a marked continuity with earlier production methods. Brine, from
which the water was evaporated to produce the salt, was collected in one of
two ways, either by its filtration from coastal sand, soil or pebbles
impregnated with salt water during high tides and periodic inundation, or by
its collection in pools or pits filled at high tide or by inland springs,
sometimes by way of a system of channels, dams and sluices.
Medieval salterns include a range of features connected with the collection
and evaporation processes, of which the most visually distinctive are the oval
or kidney-shaped middens of waste material which may cover areas of 2ha or
more. Other features usually survive in buried form beneath and around the
middens, illustrating the fact that salterns were often in use for periods of
at least a century, during which time they were occupied seasonally, their
component structures being rebuilt at the beginning of each summer or as
required. Evaporation was often aided by an evaporation kiln fuelled by peat
or wood products, of which several different types are known, and the remains
of temporary wooden buildings, wooden or wicker troughs and clay-lined pits
have also been found during excavation.
Salt was an expensive commodity during the medieval period, particularly in
demand for food preservation and curing. Salterns are known from documentary
sources and place name evidence to have been widely distributed around the
English coast and the inland brine springs of Cheshire from at least the end
of the 11th century. The industry had declined by the beginning of the 16th
century and competition with the superior and cheaper rock salt, mined from
the beginning of the 17th century, led to its demise during the early post-
medieval period.
Although it has been partially disturbed by the construction of a field drain,
the medieval saltern 800m north east of Monkshill Farm survives well as a
visually impressive monument, and the excavation of associated salterns has
indicated that it will contain well-preserved archaeological remains and
environmental evidence. Its close association with five equally well-preserved
salterns, the subject of separate schedulings, provides evidence for the
importance of the salt industry in this area of north Kent during the medieval
period.
Details
The monument includes the largest of a group of six salterns situated on the
north Kent coast. This group forms part of an original group of 11, five of
which have subsequently been destroyed. The salterns lie on the interface
between the low-lying coastal marshland on the soutern side of the Swale
estuary, periodically inundated by the sea in medieval times, and the gently
undulating, wood-fuel bearing, London clay hills further inland.
The saltern has a large, north-south aligned, unevenly-shaped midden, an
artificial heap of marsh clay waste discarded after brine extraction,
measuring 204m by up to 90m, which has been partially disturbed some time in
the past by the construction of a field drain. The midden survives as a
hummocky area rising to a height of up to 6m above the surrounding ground.
During the 1950's five adjacent, associated salterns were destroyed by
bulldozing, and archaeological investigations carried out at the time
indicated that the middens will partially overlie, and be surrounded by,
industrial structures surviving in buried form. These may include wicker or
clay-lined pits, evaporation kilns, lead boiling pans and the foundations of
temporary wooden buildings. Pottery sherds and other artefacts, including a
leather boot, discovered during the excavation suggest that the monument was
in use from at least the end of the 11th century until 1325, when Seasalter
Level and the surrounding marshes were embanked by the construction of sea
walls designed to keep out the encroaching sea and make them more suitable for
pasture. Historical records at Canterbury cathedral indicate that salt
produced on Seasalter Level was being paid as rent to the cathedral almonry
between 1198-1227.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
It includes a 5 metre boundary around the archaeological features,
considered to be essential for the monument's support and preservation.
