The monument is situated on salt marsh adjacent to Pyefleet Channel in the western half of Mersea Island, approximately 750m north west of Maydays Farm. It includes the remains of a Roman salt manufacturing area (saltern) visible as a group of earthworks clustered around a central mound. Soil from associated buried remains exhibits a distinctive red appearance caused by the salt manufacturing process, hence the term ‘red hill’ used locally to describe such sites. The principal features of the saltern are a substantial mound surrounded by a square bank and an earthwork causeway which runs from the bank to the modern sea wall. The enclosure bank survives to a height of up to 2m along parts of its southern, eastern and western sides (the northern side having been partially eroded by tidal action) and is 4m wide, enclosing an area of approximately 50sq m. On the outside of the bank is a 1m wide ditch. Within the enclosed area, in a roughly central position, is the mound of the red hill which survives to a maximum height of some 10m. Running in a south easterly direction for some 70m, the southern bank of the enclosure survives as a raised earthwork platform measuring 10m to 15m wide. This appears to form a causeway across the salt marsh, connecting the monument to the adjoining pasture south of the sea wall. It is an integral part of the monument and is included in the scheduling. The monument may belong to two periods. Excavations have shown the saltern to be early Roman in date; whereas the banked enclosure and the earthwork causeway may be later additions, representing reuse of the raised ground of the red hill as a dry enclosure for grazing livestock. Investigative excavations in 1892 confirmed that the mound contained burnt rubble, Romano-British pottery and fired clay artefacts (briquetage) used in the salt production process. The briquetage includes pedestals and firebars used for both supporting the pans of concentrated brine above the fire during the evaporation process, and for supporting vessel containing the evaporated salt in a drying chamber. Other features associated with salt making will survive within the raised platform and mound, including the settling tanks (large clay tanks in which the brine would have been left to evaporate naturally prior to heating in the kiln) and parts of the kiln structures (hearths in which the fire was lit and flues and combustion chambers for firing up the kiln). In between these structures will lie the remains of working platforms with their associated middens containing bone and ceramic artefacts. Much of the soil of the salt marsh immediately adjacent top the monument is also red in Colour; the colour resulting from the heating process used to concentrate the brine. These areas are t6hought to represent further open hearths or fire floors and are included in the scheduling. All modern fence posts are excluded from the scheduling, although the ground beneath them is included. <1>