NHER 27281 (Monument record) - Late medieval to post-medieval drainage ditches and boundaries

March 2005. Norfolk NMP.
A large group of late medieval to post-medieval drainage ditches and boundaries are visible on aerial photographs within the marshes at Heigham Holmes, Potter Heigham, and Hundred Acres Marsh, Hickling (S1-S5). These drainage ditches and boundaries are visible as both earthworks and cropmarks. The site is centred on TG 4469 2108. This site consists of a large group of quite dispersed features, covering over 2km². There are two main concentrations of features, one at TG 4448 2103 on Heigham Holmes and another to the north of Blackfleet Broad at TG 4435 2173.

The boundaries on Heigham Holmes consist of group of curvilinear and rectilinear drainage ditches with accompanying banks. The curvilinear boundaries are likely to be the earliest components, which have then been incorporated into a more rectilinear enclosure system, This site is located within the former Thurne estuary and it is possible that these irregular boundaries originate from earlier adaptation of natural creeks formed during the drying out of the formerly tidal area, similar to those on Halvergate. The boundaries adjoining those mapped by NMP have been classified by the Norfolk Historic Landscape Characterisation project (HLC) as a few of the rare incidences of the boundary type ‘Grazing marsh - curvilinear - anciently enclosed’ in the upper valleys.

Comparison of these earthworks with the 1801 Potter Heigham Enclosure Map (S6) indicates that some of these boundaries were still in use, such as the slightly curving parcel of land centred on TG 4424 2106. This is clearly apportioned to Bishop of Norwich on the map (S6). However many of the other irregular divisions are no longer in use, or have been made obsolete by the Enclosure Act, and are cut through by later, more regular, drains. The few irregular and curvilinear boundaries remaining in use in 1801 have all been removed by the 1840 Potter Heigham Tithe map (S7), such as the meandering channel to the southwest of the site, centred on TG 4433 2020. These drainage ditches appear to continue to the east of the Eelfleet Wall and some of the slightly irregular channels to the immediate east of Blackfleet Broad correspond with drains marked on the 1816 Horsey Enclosure Map (S8). Although again many of them have been replaced by straighter and more rectilinear enclosure, especially to the south, towards the Hundred Stream where none of the earlier boundaries survive.

The more curvilinear boundaries and drains appear to post-date and cut some of the extraction pits on Heigham Holmes itself (NHER 27280). However the drainage ditches appear to continue either side of the Blackfleet Broad, possibly suggesting that the extraction in this area is later than the major boundaries. Although this seem unlikely and it is more likely a reflection of the fact that many of the curvilinear and irregular drains in this area would have originally been meandering creeks within the Thurne valley and as such would have possibly pre-dated the medieval extraction. Also Blackfleet Broad looks like quite a shallow workings, probably only removing clay and not the peat lying under the clay.

The drainage ditches and boundaries also continue to the north of Blackfleet Broad and to the west of Horsey Mere. The linears form a reasonably regular system of drains, following the same alignment as some of the drains to the south and are arranged diagonally to the later post-medieval boundaries. These all appear to pre-date the layout marked on the 1842 Hickling Tithe Map (S9). Some of these former drains and the associated embankments are still visible as earthworks in 1945-6; centred on TG 4396 2193, TG 4437 2181 and TG 4426 2172. Not all of the drains in this area fit into the regular layout and it is likely that some of them reveal fragments of earlier systems of drainage, some possibly associated with the irregular creeks that are visible meandering across the Hundred Acre Marsh to the northwest of the site. The wider and slightly more irregular channel, running from TG 4397 2164 to TG 4398 2140, is likely to have originally been a natural creek, which has been incorporated into the late medieval to post-medieval drainage system and is visible on the 1801 Potter Heigham Enclosure Map (S6).
S. Massey (NMP), 29 March 2005.