The earthwork remains of a large sub-circular mound of uncertain date seen at TQ 8725 7704 within Grain Marshes. The mound measures c.25m x 35m and has a deep central depression. It appears on the current OS map of the area. It is possible that this is the remains of a medieval saltern mound.

These mounds are the result of large-scale salt manufacturing where brine was extracted from salt-rich sands and sediments, concentrated and evaporated using process known as sleeching. The discarded waste material from the process built up around the production area into a sizeable mound, often with a hollow in the centred where a hut stood. These medieval saltern mounds are typically described as floriate in form because of their irregular lobed formation of dumped waste. They often occur in clusters around former and surviving tidal water-courses within the marsh. There has been considerable reclamation and subsequent sea wall construction since the medieval period which has isolated these sites from the sea.

Many of these mounds were subsequently utilised as sheepfolds, sheep washes and stock refuges in the post medieval period because of their slightly elevated position in the readily flooded marshes.

Roman finds have been extracted from some of these sites, but are believed to be from the lower levels and not associated with the mounds. Post-Roman flooding and silt deposition has resulted in Roman sites lying typically several feet below the current land surface.

This site was mapped from Environment Agency lidar imagery as part of the English Heritage: Hoo Peninsula Landscape Project. (1)

<1> Environment Agency, 2001, LIDAR TQ 8676 Environment Agency D0015786 APR-2001 (Digital archive). SKE55929.