Medieval saltern 950m north east of Monkshill Farm, one of a group of six on Seasalter Level


Heritage Category: Scheduled Monument

List Entry Number: 1012971

Date first listed: 29-Jul-1957

Date of most recent amendment: 07-Jun-1995


Ordnance survey map of Medieval saltern 950m north east of Monkshill Farm, one of a group of six on Seasalter Level
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The building or site itself may lie within the boundary of more than one authority.

County: Kent

District: Canterbury (District Authority)

County: Kent

District: Swale (District Authority)

Parish: Hernhill

National Grid Reference: TR 07389 63651

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.

The medieval saltern 950m 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 subjects of separate schedulings, provides evidence for the importance of the salt industry in this area of north Kent during the medieval period.


The monument includes the smallest saltern of a group of six 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 a west-east aligned, kidney-shaped midden, an artificial heap of marsh clay waste discarded after brine extraction, measuring 54m by up to 47m. The midden survives to a height of up to c.5m. 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.


The contents of this record have been generated from a legacy data system.

Legacy System number: 27003

Legacy System: RSM


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,

End of official listing