EDO5711 - Grimstone Reservoir, Stratton; evaluation 2011

An evaluation of the site of an extension to the south of Grimstone Reservoir, comprising the machine excavation of five trenches measuring 20m by 1.6m to the depth of either archaeological features or natural geology. Trenches 2 to 5 were located to investigate geophysical survey anomalies while Trench 1, the northernmost, was in an area that appeared blank in the geophysical survey. Two small post holes and part of a substantial ditch were revealed in Trench 1; these could not be dated or phased in relation to each other or other features on the site. Trench 2 was dug to investigate the west terminus of a curvilinear magnetic anomaly, and revealed a substantial beehive-profiled pit cut by a ditch. This curving anomaly was also cut by Trench 4 and Trench 5. In Trench 4 it appeared as a truncated V-profiled ditch recut by a deeper full V-profiled ditch. In the northern part of the trench an oval anomaly within the area enclosed by the curvilinear features proved to be a pit cut by a substantial posthole; it appeared to be filled with a series of deliberate deposits. Trench 5 was placed over the east terminal of the south arc of the north curvilinear anomaly and the wider arc of a curvilinear at the south-eastern end. A ditch terminal was found in the former area and a substantial pit in the latter, which showed possible episodes of recutting and deliberate deposits. These opposing north and south curvilinear ditches with opposing gaps of around 4 metres on the west and east sides encircled an area with internal diameter of around 8 metres, and were of later Middle Iron Age date. The distance between the terminals was such that it would not have formed an enclosure and was unlikely to be associated with a roundhouse. In the centre a shallow pit with diffuse boundaries was cut by a single pit or substantial posthole. The archaeologists on site noted that a single post in this location might have had totemic significance, particularly when considered alongside the deliberate filling of the pit/posthole and more gradual infilling of the recut curvilinear ditches, which occurred during the later 1st century BC or the 1st century AD and appear to be the latest events on the site. Trench 3 crossed a linear anomaly at its south west end and an oval anomaly at its north-east end. A small half oval cut pit was found to contain five hemispherical discs with concentric central hemispherical perforations, pitched upright, closely set with curved edges downwards. In the course of the evaluation 877 sherds of prehistoric pottery were recovered, dating from the 5th century BC to the 1st century BC/AD. The overall quality of the material was excellent and preliminary analysis suggested it was potentially of regional significance and worthy of further study in combination with material from earlier work in adjacent areas. Animal bone and some human bone were recovered, and 24 pieces of struck flint probably Early Iron Age and contemporary with the pottery found from the same phase. The excavators noted this unusual occurrence of a flint assemblage with an identifiably Iron Age component, also felt to necessitate further study. The orientation of some anomalies strongly suggests that the scheduled field system north of the reservoir was part of an extensive co-axial field system served by a north-south track, and which included fields identified from air photographs to its south. Finds from this evaluation suggest that the field system was in active use from at least the 5th century BC until the 1st century BC/AD.