What’s in a Sherd.
The autumn programme started this year with a talk from our president David Dawson. David’s research into the analysis of excavation pottery has the potential to revolutionise our understanding of the past and it is no wonder that his talk drew an audience from a wide area.
David started by describing in simple terms how to process excavation finds before turning to the more complex matter of identifying the form and fabric of a pot. These two elements of the process can help to determine not only age and function but also where a pot was made and how far it has been traded. Context, he emphasised, is everything. Without this it is impossible to make a valid interpretation.
Since the 1960s, the main method of identifying the fabric has been the ‘eyeball method’ preferably with the aid of a magnifying glass, although David rarely seems to need this. The late Professor D. Peacock of Southampton University improved on this method by taking thin sections which could be examined under a microscope and, while this was useful for identifying the temper or inclusions, it did not help greatly with the identification of the clay matrix.
The Peacock method was followed by the I.C.P. method or Inductively Coupled Plasma method using Atomic Emission Spectroscopy. This method does identify the minerals even those in the clay matrix but it presents the results as a list of tables which are not always easy to interpret.
The latest advance which David has been spearheading is called Quemscan and is being developed in conjunction with the Camborne School of Mines. Quemscan is an automated scanning system which has been used to analyse rock samples from the moon. The technique produces a visual map of what is in a sherd picking up the matrix as well as the inclusions and it also produces pie charts showing the percentage of every mineral that is present.
Results to date have shown some interesting correlations between the pottery found in Westbury-sub-Mendip and variously Wells, Chewton Mendip and Hope Wood, Ebbor Gorge. Common types appear to have been traded widely while others were made locally from local clay and local temper much as still happens in Africa today.
David also took the long view of pottery manufacture commenting on the Ceramic Revolution that took place between 1450 and 1650. During this period, ceramic imports increased bringing new forms and functions as well as new types of decoration. It is also possible that potters came too, fleeing religious persecution at home. Whatever the cause, forms and glazes diversified at this time and the country potter flourished until, in the nineteenth century, the process became industrialised and brick and tile manufacture evolved to meet the needs of a housing boom.
We have been privileged to hear David talk about this development while still in its early stages and shall wait with eager anticipation the further insights that are sure to emerge as more results become available.