A rectangular soilmark close to the outwork of Bat's Castle, noted on aerial photographs, appears to show the location of a field boundary predating Dunster Park, and possibly the medeval deer park.

A rectangular soilmark is visible on aerial photography at SS 9901 4200. One side is traceable as a small ditch 0.2 metres deep. [1,2] This is probably a medieval or later field. [3] A soil mark, southeast of Bats Castle showing a bank and ditch is visible on aerial photography. It is possibly a large square enclosure. [1,4,5] This joins to the linear earthwork (MSO9083) and may be associated. [6] Nothing can be seen on the ground. [7] The area in question, immediately to the east of the outwork at Bat's Castle, has been recently scarified to encourage heather growth and no such feature is discernible. [9] A rectangular soilmark is clearly visible on aerial photographs, east of the outwork of Bat's Castle. Centred at approximately SS 9901 4200, the soilmark appears to show the location of a field boundary defined by a narrow bank surrounded by a ditch on both sides. The boundary defines two sides of a rectangular enclosure measuring 78 metres long by 55 metres wide. The enclosure presumably predates the creation in the 18th Century of the post-medieval Dunster Park, and possibly predates the medieval deer park, first recorded in 1279. Given the concentration of later prehistoric material and monuments in this area, the possibility of a prehistoric date cannot be ruled out. [10-11]