Geoscience Reference
In-Depth Information
A key point here is that fi gure 13.10 implies a dynamic and spatially variable
Quaternary geography associated with rapid climate change events during the last
cold stage and this is in marked contrast to the rather static geography associated
with the last cold stage as portrayed in fi gure 13.4. The response of ecosystems and
landscape processes to rapid climate change will be modulated by local and regional
environmental conditions and an appreciation of these environmental factors is
clearly very important. The ability of human groups to cope with these changes will
determine their success in the long term.
More generally, Bowen (1979) has proposed a basic working philosophy for the
study of the Quaternary that represents a combination of
geological appraisal
for
sequence and
geographical evaluation
for spatial reconstruction, coupled with the
particular problems and techniques serving it - be they palaeobotanical, palaeocli-
matological or geomorphological (or archaeological in this case). He goes on to
argue that the time-space 'event sequence' forms the vehicle for ordering the view
of the world on this basis. If we consider this approach in relation to fi gure 13.8,
any assessment of the temporal resolution of an environmental archive is essentially
a geological appraisal and any attempt to assess the sensitivity of a system will
require a geographical evaluation of the lake basin, rockshelter or marine environ-
ment in question. At the same time a key aspect of any geographical evaluation
must try to factor in the role of environmental thresholds and the potential for a
spatially variable response of natural systems to rapid climate change as illustrated
in fi gure 13.10. This problem is analogous to the complex response model put
forward by Stan Schumm in the 1970s. He argued that different parts of river basins
may respond in radically different ways to an environmental change by either
aggrading or incising channel beds for example (Schumm, 1977)
Quaternary Geography and the Human Past
An important challenge is the development of new interdisciplinary approaches that
will allow the cultural data from key Middle and Upper Palaeolithic sites to be
examined in relation to the high-resolution proxy climate records for the last cold
stage. One way of getting around the defi ciencies inherent in the records from indi-
vidual rockshelter and cave sites is to integrate the data from many sites over much
larger spatial and temporal scales. Gamble et al. (2004) have compiled a database
of over 2,000 radiocarbon dates from across Western Europe and this has allowed
them to explore, in very broad terms, population dynamics across Europe from
Britain to the Mediterranean between 30,000 and 6,000 BP. In this example, the
radiocarbon dates come from archaeological sites across Western Europe and all of
them have been calibrated to facilitate comparison with the GRIP ice core record
(fi gure 13.11). This has allowed, for the fi rst time, a regional scale analysis of human
response to changing ecological conditions.
The radiocarbon dates have been used as a proxy for Upper Palaeolithic popula-
tion history. Figure 13.11 shows the importance of southern Europe as a refuge for
humans during the last cold stage but it also points to extreme cold tolerance by
human populations. The analysis by Gamble et al. (2004) suggests that climate
affects population contraction rather than expansion and they also argue that the
dispersal of modern humans across Europe took place within wide climatic toler-
ances. These people had strategies to cope with extreme conditions so that explain-
ing such events by general trends of warming or cooling is not possible.
