MMO2945 - Possible post-medieval prospecting pits on Horsen (Monument)

Several small pits, linear features and associated spoil heaps are visible as earthworks. These may be associated with several large prospecting trenches that are visible in the vicinity, making the features post-medieval in date.

Several small pits and associated spoil heaps are visible as earthworks on Horsen, Exmoor. Centred at approximately SS 7833 3728, each pit measures between 5 and 8 metres across. They are not depicted on the 1st Edition Ordnance Survey map of 1890, suggesting they were abandoned prior to this date. Several large prospecting trenches are visible in the vicinity, which were cut in the mid 19th Century in an attempt to trace the extent of the lodes of Blue Gate and Wheal Eliza Iron mines, and it is likely that these pits are part of similar activity. [1-3] As part of the Exmoor Mires Project, South West Archaeology were contracted to undertake a non-intrustive walkover survey of the proposed mire restoration area on Spooners. During which was found a pair of mineral exploration pits, two linear features and a mineral exploration pit. The pair of pits were each c. 6 metres in diameter, two phases were clearly visible, with the lower pit partly infilled by spoil from upper pit. The first linear mineral exploration trench was c. 20 metres long, located at at 90 degrees to the slope, with the trench measuring c. 2 metres in width and 0.5 metres in depth and the associated bank measuring c. 2.5 metres across and up to 0.5 metres in height. The second linear mineral exploration trench measured c. 17 metres long, was located at 45 degrees to the slope with its slightly irregular upcast bank at the downslope side; the irregular base of trench suggests two phases. The mineral exploration pit formed a sub-circular hollow 2 metres by 1.5 metres across and was cut 1.4 metres into the slope; a discrete upcast mound was located on the downslope side 3.5 metres by 2.5 metres in size, and 1.2 metres high. [4] The Historic Environment Officer for the Exmoor Mires Project undertook a non-intrustive walkover survey of the proposed mire restoration area on Spooners, which included this site. Noted were two adjacent pits c. 6 metres in diameter with spoil dumps on their northern, downslope sides. These were interpreted as probable prospecting works. Also visible as earthworks were two linear features; the first being an excavation c. 20 metres long with upcast spoil on the eastern side, the second being a cut oriented north-south at c. 45 degrees to the slope, measuring c. 20 metres long, 5 metres wide and 1 metre deep with spoil on the western and southern sides. The first is likely a mining or prospecting work, while the second is probably a mineral prospecting work. In addition a sub-circular pit dug into a slope, with a discrete mound of upcast located downslope was noted; again this is probably a prospecting work. All features are considered to be associated and are likely of 19th Century date. [5]