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) |