Following on from my previous post about trend surfaces, I have now completed my proposed next step in extracting trends from the PAS data, by creating trend surfaces for the finds associated with each of our broad time periods. To begin, here is a reminder of the trend surface for all PAS data:
Now by period:
Although these should all be treated as very rough models, certain things do stand out. For the Bronze Age, it is obvious that the main peaks seem to be occurring in the far west of Cornwall, the Isle of Wight and Suffolk. In the Iron Age, the peaks are low, but I do think I can perhaps see the main areas of circulation for coinage showing up in the blue tones. The Roman picture largely replicates the pattern for all periods (which is unsurprising as Roman finds make up a large proportion of the PAS database), but with a notable lack of finds in the west country. For the early medieval, the peaks seem to be around the east and south-east coast.
To stretch interpretation perhaps beyond where I should, I might suggest that the fact that the peaks in the Roman and early medieval period are in similar locations to the overall dataset suggests that the dominant attribute governing where finds of these date are found would be where metal detecting activity is most popular (of course, this is partly self-fulfilling, as people are bound to find metal detecting more appealing in areas with lots of metalwork in the soil). However, the fact that the peaks in the prehistoric periods are somewhat differently located suggests to me that patterns in the these data are more likely to be genuine representations of past behaviour. Perhaps?
NB: Scotland and Wales are marked as terra incognita on my maps as they are outside of EngLaId’s spatial remit.