- Chapter Five -
(see Collis, Chapter 10). The majority of muri gallici occur in non-Mediterranean
France, with outliers occurring in Belgium (at Rouveroy and Lompret, province of
Hainaut: Cahen-Delhaye 1982; Cahen-Delhaye and Jadin 1990) and in Germany,
where the most easterly example known is the final fortification, replacing earlier
defences of Kelheim type, at Manching (van Endert 1987). The elaborate fortification
discovered on the promontory fort which occupied the Cathedral Hill, adjacent to
the Rhine at Basle, Switzerland, melds elements from these two traditions (Fiirger-
Gunti 1980) and provides a good indication of the increasing variation which can be
expected as a result of large-scale excavations of (rather than narrow cuttings through)
such remains.
Professor Dehn, more recently supported by Frey (1984), has hypothesized
that elements of the architecture of muri gallici forts derive from Italian and other
southern models, noted by Celts during their presence as settlers or mercenaries in
such areas. Against this has to be set the quantitatively preponderant evidence, which
indicates that the construction of versions of such stone, earth and wood fortifications
was a long-lived tradition in temperate Europe. However, on the southern fringes of
the hill-fort area, in Provence and Languedoc, the dry-stone-built forts characteristic
of that area display different borrowings from Mediterranean traditions (Dedet
and Py 1985), including in areas at least latterly occupied by groups bearing Celtic
names.
A particular problem is set by some of the fortifications which show evidence
of intense burning. These may usefully be subdivided into two series, on the basis of
differences in their geological make-up. Vitrified forts are characteristic of igneous
and metamorphic zones, and appear particularly numerous in France (Ralston 1981,
1992) and Scotland (MacKie 1976); calcined examples occur in limestone and related
sedimentary areas. A key question which has attracted attention since the eighteenth
century is whether the resolidified but distorted masses of stonework (implying
the application of temperatures in the vicinity of 1,000 degrees Celsius) visible in the
vitrified walls represent the outcome of deliberate constructional intent on the part
of their builders or not. If the former perspective is upheld, the technology is
certainly not narrowly delimited spatially or in time; a wide date range for such
works is suggested by radiocarbon determinations, and an even wider one by the
thermoluminescence dating of Scottish examples (Sanderson et al. 1988).
In the case of the vitrified forts, a number of strands of evidence may be adduced
to argue that vitrification is rather a product of the destruction, intentional or not,
by fire of timber-laced walls. In a number of instances, only a small proportion of
the enceinte displays the characteristic evidence. Further, excavation at Dun Lagaidh,
Ross and Cromarty District, Scotland (MacKie, 1969), demonstrated vitrifaction
overlying the slots of timbers which have simply rotted in situ. Experimental
evidence shows that it is possible to replicate the characteristics of the vitrified walls
by igniting timber-laced replicas (Ralston 1986) (Figure 5.4). In some instances,
the deliberate destruction of fortifications by fire either in the aftermath of conflict
or in other circumstances would have provided, in the walls glowing red-hot against
the night sky, a spectacular advertisement of power or intimation of the site's
abandonment.
Whilst the vitrification of fortifications seems thus adequately explicated, there are