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Medieval saltern 1.05km north east of Monkshill Farm, one of a group of six on Seasalter Level

A Scheduled Monument in Hernhill, Kent

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Latitude: 51.3347 / 51°20'4"N

Longitude: 0.9778 / 0°58'40"E

OS Eastings: 607527.36172

OS Northings: 163720.250153

OS Grid: TR075637

Mapcode National: GBR SW1.81G

Mapcode Global: VHKJQ.WQS6

Entry Name: Medieval saltern 1.05km north east of Monkshill Farm, one of a group of six on Seasalter Level

Scheduled Date: 29 July 1957

Last Amended: 7 June 1995

Source: Historic England

Source ID: 1012972

English Heritage Legacy ID: 27004

County: Kent

Civil Parish: Hernhill

Built-Up Area: Waterham

Traditional County: Kent

Lieutenancy Area (Ceremonial County): Kent


The monument includes one 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 southern 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 an unevenly-shaped midden, an artificial heap of marsh clay
waste discarded after brine extraction, measuring up to c.130m by a maximum of
around 97m. The midden survives to a height of up to c.2.5m in places. 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
buldings. 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
The modern electricity pylon which partially overlies the monument on its
north western side is excluded from the scheduling, although the ground
beneath it is included.

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.

Source: Historic England

Reasons for Scheduling

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.

The medieval saltern 1.05km 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

Source: Historic England


Books and journals
'Archaeologia Cantiana' in A Group of Mounds on Seasalter Level...and the Med imbanking..., , Vol. 70, (1956), 44-67
Source 2 Cantab Cath Accnts 1198-1227, RCHME, TR 06 SE 6,

Source: Historic England

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