- Chapter Sixteen -
on the hill-fort ramparts date to the second/first centuries Be and were used for
processing a zinc-and lead-rich copper. The hill-fort itself stands over a copper mine
which could have supplied the right ore to produce this metal, a mine, moreover,
that is believed to have been exploited in Roman times. The same raw copper and
associated slag have been excavated from a metallurgical context at the small hill-fort
of Llwyn Bryn-dinas in the Tanat valley with a C-14 date that takes. the use of this
metal back at least to third century Be, perhaps even further. Together with other
excavated material and the analysis of bronze objects it is possible to demonstrate
the existence of a copper extraction industry based on the ores of this area, with
products mainly distributed in north and east Wales, although examples are known
from as far away as Llyn Cerrig Bach in Anglesey (Northover, 1991a; Musson et al.
1993). It appears that the source was not used before the fifth-fourth centuries, and
it may have come to an end in the first century Be.
The same chronology applies to a second source for which the evidence is rather
more circumstantial. A large quantity of bronze has now been analysed, with a
very characteristic impurity pattern in which arsenic, cobalt and iron are the most
important elements; where nickel is present there is always more cobalt than nickel.
This metal is most common in southern and south-western England and on several
sites, for example Maiden Castle hill-fort (Northover 1991 b), all the metalworking
waste is of this composition. The distribution of this metal hints at a source in the
south-west and there is some confirmation from analyses of bronze age metalwork.
In about the fourteenth century Be there is a type of bronze axe specific to Devon
and Cornwall and those examples clustered around Dartmoor have the same
arsenic/cobalt/iron impurity pattern (North over unpublished). A source in this
area also has the benefit of being close to major tin sources. There has always been
speculation about the exploitation of the mineral wealth of Devon and Cornwall in
prehistory. Both tin and copper were certainly produced there in the Bronze Age,
but it is impossible to gauge how much was mined. An industry of significant size in
that region seems to be a creation of the Iron Age so it can be argued that classical
writers did actually have knowledge of a real industry that was in a position to export
both tin and bronze. There is a long way to go in testing the evidence but it may
well be more than coincidence that the sheet bronze in the cauldrons found at La
Tene itself are made of the same type of bronze. It is also noteworthy that the same
impurity pattern appears in both the earliest cast bronze Celtic coins made in Britain
and their Massiliote prototypes (Northover 1992).
These are two of the best characterized metal types in the British Iron Age. There
are several others and some at least must represent imported metal coming from
either the Continent or Ireland. We have seen that there was a change in the utiliza-
tion of metal resources at the beginning of the La Tene period. The demise of the
two metal groups detailed above in the mid-first century Be and the increasing
importance of others shows that further major changes occurred at that time. It is
tempting to associate them with the events of, or consequent upon, either supposed
Belgic migrations to Britain, or the Roman occupation of Gaul and the Romans' first
incursions into Britain but it is impossible to be that precise in the dating of any site
or artefact. Both literary evidence and events after the conquest show that the
Romans were interested in British resources, so it is curious that what appear to have