More information : The possibility that the ramparts and ditches forming the bailey to the medieval motte of Castle Hill (TL 88 SE 20) might be iron age in origin was first suggested by Rainbird Clarke in the early 1960s, and was subsequently tested by him during excavations carried out in 1962. These excavations recovered iron age and some earlier material including Beaker pottery and an EBA flint arrowhead, and indeed produced evidence for two phases of a bivallate iron age 'hillfort'. The excavations also showed that the prehistoric defences had been substantially remodelled in the medieval period to form the bailey to the later motte inserted within their circuit. (1)
The earthworks at Castle Hill comprise two closely-spaced and concentric lines of rampart and ditch which curve around the north side of a large motte and then run away south-east from it for over 100m until cut by Castle Lane. North of the motte both lines of defence are well-preserved for about 120m west of a modern tarmacked footpath across the site, after which they have been quarried away and their course partly built over. East of this path the form of both ramparts alters. The outer rampart quickly loses height and is increasingly broken; it disappears completely before Castle Lane whilst its ditch becomes very shallow and spread. In contrast the inner rampart and ditch gain in height/depth, and towards Castle Lane begin to pull in slightly from the line of the outer defences. The earthworks are now mostly under mown grass and lie in an area of public parkland. Amorphous hollowing within the interior of the hillfort east of the motte in the area now known as Military Parade would seem to be post-medieval surface quarrying.
Most of the extant earthworks presumably either date from or have been at least reworked in the medieval period as part of the defences of the motte and bailey (see description on TL 88 SE 20). Nevertheless, elements of the earlier defences may be suggested. First, the motte is surrounded by a steep-sided ditch some 5m wide which closely conforms to the shape of the motte and should be contemporary with it. North of the motte this ditch cuts into and sharpens up the rear face of the inner rampart and then as it curves to the east pulls away from the line of the rampart leaving a berm a little below its crest, showing clearly that the motte postdates this part of the inner rampart. It is unclear, however, if both lines of defence in this sector are intact iron age features, especially when compared to the poor survival of the outer rampart and ditch further east. It may be that the prehistoric defences here have been remodelled to strengthen the defences of the medieval castle around the motte. But if so the very top of the inner rampart is probably iron age especially where it has been left behind by the cut of the motte ditch. Just past this berming a ditch springs north-east off that of the motte and breaches the inner rampart. (The breach is followed by the modern north-south tarmacked footpath already mentioned). This breach is clearly the start of the ditch to the bailey which then turned east and south-east, presumably following, enlarging and therefore largely destroying the iron age inner ditch. However, towards Castle Lane the bailey defences (rampart and ditch) diverge from the course of the outer defensive line and therefore presumably from that of their iron age predecessors also, suggesting that evidence of the original ditch may survive immediately behind the outer rampart whilst the original inner rampart will here have been largely destroyed.
Clarke (auth 1) and others (eg 2a, 2b) have suggested that the curves of Old Market Street and Ford Street south of the surviving earthworks may mark the line of the destroyed southern defences of the hillfort/motte and bailey. However, occasional watching briefs along the present street frontages have failed to produce evidence of either ditches or banks (2c), and it therefore seems more probable that the hillfort was more of a promontory fort using the river Thet to define and defend its southern side. If so, the defences may have met the river bank at approximately TL 8718 8278 in the south-west and at TL 8769 8278 in the south-east; this would mean that the hillfort should be centred at TL 8745 8275. See TL 88 SE 20 for a discussion of the probable circuit of the medieval bailey.
The extant earthworks of the hillfort are part of SAM Norfolk 60. (2d)
Earthworks surveyed at 1:1250 by RCHME for the OS's upgrade of the basic scale mapping of Thetford; plans, a level 3 descriptive text plus other associated archive material are held in the NMR archive. (2) |