The Archaeology of Britain: An introduction from ... - waughfamily.ca

British archaeology since 1945
• 3 •
World War were little changed since the nineteenth century and involved correlations with
documentary sources. These historical connections become possible from Roman Britain with
early chronicles, hagiographies and the emerging written record and, more reliably, with the later
histories, accounts and documents of the Middle Ages. However, for pre-Roman times, chronology
could still be established in only relative terms; it was interpreted on the basis of perceived
artefact analogy or founded on the premise of diffusionist theory, often based on the clumsy
‘three-age’ development of technological progression from stone through bronze to iron.
Alternatively, cross-dating was possible, ultimately with literate civilizations, but only intermittently
and only as far back as the emergence of Middle Eastern civilizations some five millennia ago.
Major advances followed in biological, physico-chemical and geological sciences, notably with
Libby’s 1949 discovery of radiocarbon dating which depended on measuring the decay rate of
the radioactive isotope of carbon in organic materials. Although the hypotheses on which the
technique was developed have required modification, notably in the ‘radiocarbon revolution’ of
the 1970s when the need for major correction factors was recognized, the measurement of
thousands of absolute dates has been of primordial importance in securing and modifying the
chronology of prehistory. Radiocarbon measurement from archaeological materials requires
adjustment or calibration according to the derived dates of sequences of tree-rings
(dendrochronology) which mirror inconsistencies in the amount of radiocarbon in the atmosphere
through time.
The effects of these calibrated dates have been both to push back in time the start dates for
various innovations, and to lengthen the timespans of various segments into which the
archaeological record is traditionally sub-divided. Thus, in the mid-1950s, the Neolithic period
was considered on the best evidence then available to have endured for several centuries either
side of 2,000 BC; early radiocarbon dates pushed this back to around 3000 BC; while recent
calibrated dates place the British Earlier Neolithic even earlier (see Chapter 4). Radiocarbon
dates have also been instrumental in demonstrating that the initial interpretations of some elements
in the archaeological record were awry (e.g. Fairweather and Ralston 1993). Dendrochronology is
also valuable in its own right, although its scope is restricted by the need for suitable preservation
of wood in archaeological contexts. Sequences can provide dates correct to the nearest year; they
have a particular role to play in post-Roman periods where structural timbers may survive and
when radiocarbon dates become of decreasing value.
Other technical innovations
Other techniques, too, have made important contributions to the refocusing of research agenda.
Developments of the aqualung and the drysuit, for example, have physically extended the scope
of British archaeology into lakes and coastal waters, as witness work on the Mary Rose and on
Scottish crannogs, while the widespread application of aerial photography (Wilson 1982) has had
a major impact on the quantity of sites now recorded. New categories of site have also been
identified from the air, particularly as cropmarks in free-draining soils in the agricultural lowlands
(as far north as the Moray Firth) of eastern and southern Britain (Figure 1.2). The technique has
become more refined and versatile, and it currently underpins most regional sites and monuments
records. Through the identity of former field and land boundaries, aerial imagery has been able
to illustrate the vast extent of some systems of earlier settlement and landuse; it has been in part
responsible for the shift away from the study of individual monuments and their artefacts to the
investigation of whole landscapes and of their infrastructure (Darvill et al. 1993). In its turn this
has had a direct influence in matters of heritage management.