Red hill (salt making)

Red Hill is an archaeological term in Britain for a small mound with a reddish colour found in the coastal and tidal river areas of East Anglia and Essex.

[1] However some early comparisons to salt-processing sites in Brittany in the early Twentieth century lead to tentative suggestions that salt was at the heart of the Red Hills' purpose,[6] with further excavations in Britain of sites similar to the Red Hills of Essex and East Anglia at Ingoldmells in Lincolnshire and Hook in Hampshire choosing this interpretation over the alkali explanation.

[1] Ernest Linder's 1937–1941 excavations of Red Hills at Canvey Island in South Essex began to draw upon salt-making as the main suggestion for what had been occurring at these mounds.

[1] The vast majority of Red Hills are located on low-lying coastal flats in tidal estuaries and in back-waters like Hamford Water between Harwich and Walton-on-the-Naze in Essex.

[3] The height of many mounds has been much truncated by ploughing, with others located close to rivers and the sea either being eroded away or covered with alluvial silt,[1] but an average sized mound at Peldon in Essex, 0.2 acres in size, still stands at a height of roughly 1.3m (meaning a volume of about 1000 cu metres, equivalent to 1500 tons of earth).

[1] Rows of oval clay-lined pits dug into the alluvium around the Red Hills are interpreted as tanks for holding sea water.

[11] Other hearths containing Roman tile have been found at Leigh Beck on Canvey Island, and others have been located at Red Hills along Fenn Creek near South Woodham Ferrers.

[1] Briquetage refers to the broken fragments of clay structures found in great quantities at Red Hill sites.

[1] Some briquetage has lost its red colouration during its use as part of the salt evaporation furniture, turning grey, purple or brown.

[1] Sea-water may have been collected in tidally-fed sun pans cut into tidal channels to allow for solar evaporation in the initial stages of the process, although no such features have been positively identified.

[1] The depth of these tanks suggests that they were designed to allow the alluvial mud and other unwanted solids in the water to settle to the bottom, to be emptied out later.

[1] In theory the tray vessel could have been topped up with water roughly one hundred times before the concentration of the bittern impurities and pan-scale left behind became too high.