- Chapter Five -
representing a precocious use of the Kastenbau technique, most commonly recorded
further east. Iron age instances of the employment of wood in multi-material fortifi-
cations are recorded from Dacian areas of east-central Europe (Glodariu 1983)
to Iberia, where rare examples have been identified (de Palol 1964). One of the
fortification lines at the Castelo de Monte Novo in the Evora region of Portugal
displays evidence of vitrified stone (Burgess, pers. comm.), discussed further
below.
Within the later Hallstatt and La Tene areas, numerous constructional variants
employing timbers are recorded. A primary distinction can be proposed between
examples which have earth-fast vertical timbers exposed in the front face, either as
components of continuous wall-faces or interspersed with panels of dry-stone work,
and those which have only, in effect, an internal lattice-work of horizontal timbers
anchoring the core materials. The first suite may also have a second earth-fast
alignment of timbers on their inner margins. Grossly to simplify matters, the former
set is tentatively considered more characteristic of central, and the latter of more
westerly regions of the Continent. In the United Kingdom, an equivalent distinction
can be drawn between the south and north, although in the last-mentioned area in
particular such sites are complemented by those surrounded by earth-fast palisades,
including some with closely set pairs of stockade lines which may initially have
formed the front and rear faces of narrow box-walls. Variations in architectural detail
may be expected to complicate the picture particularly in the vicinity of gateways
(Figure 5.3).
The aforementioned distinction, and exceptions to it, can be illustrated by refer-
ence to the wood-using fortification types present in the later (primarily La Tene
C2/D) Iron Age of continental Europe (Collis and Ralston 1976; Audouze and
Biichsenschiitz 1992). In south Germany, the dominant series (Kelheim type) of this
period is a simplified form of the vertical-post-and-stone-panelwork arrangement, in
which the external timbers are no longer anchored by cross-members to an inner row
of posts set into the ground, but are believed to have been tied back simply into the
wall-core. Isolated examples of this type occur as far west as the site of Castillon in
Normandy, France.
In the west, the principal series takes its name from a description (De Bello Gallico
VII.23) provided by Julius Caesar of the defences he encountered at the siege of
Avaricum (Bourges, in Berry) in 52 Be. This, the murus gallicus type, is characterized
by an internal framework of transversal and longitudinal beams, fronted by a near-
vertical external skin of stonework through which the ends of the transversal beams
projected. The timber lattice was infilled with a variety of core materials. The inner
margin of such walls can consist either of a vertical face, or of a sloping ramp. The
technique is thus that of fa terre armee, used by French military engineers as recently
as the 1950S in Indochina, and still employed in civil engineering projects. A major
innovation, comprised in the archaeological definition of this type although not
recorded by Caesar, is the incorporation of long, quadrangular-sectioned iron spikes,
augered into at least some of the intersections between timbers. This conspicuous
consumption of iron, given that the spikes seem to confer little advantage in terms of
structural stability, is an important element in the demonstration of the significant
upturn in production which corresponds to the so-called 'civilisation des oppida'