Chewton Mendip Precinct Field Excavations & ‘Origins of Chewton’ Project

Experimental Archaeology: Making Replica Medieval Coarsewares

December 2018

Pip Osborne BA (Hons) & Jennifer Waters

Community Archaeology on the Mendip Plateau (CAMP) Illustrations

Cover Pots emerging from the embers (Photo. Rosemary Walker) Figure 1 Chewton Mendip Pottery Fabric Type Series Figure 2 Ham Green sherd from the excavations Figure 3 Coarseware type 31 from the excavations Figure 4 Silts from River Chew bed Figure 5 Shrinkage bars before firing Figure 6 Pots ready for firing Figure 7 Bonfire taking hold Figure 8 The pots emerging from the fire Figure 9 Pots after firing Figure 10 Shrinkage bars after firing Figure 11 Dig field 3 pot and Type 18 of CMFTS unfiled Figure 12 The same sherds filed Figure 13 Naturally occurring inclusions from the Dig field clays Figure 14 Naturally occurring inclusions from the Woodside clays

2 Contents 1.0 Background to Project……………………………………………………4 2.0 Rationale for Project……………………………………………………...5 3.0 Methodology……………………………………………………………...6 3.1 Gathering clays, silts and other inclusions……………………….6 3.2 Preparing the clays ……………………………………………….6 3.3 Preparing the inclusions from the River Chew silts………………6 3.4 Making the Pots and Bars…………………………………………7 3.5 Drying process…………………………………………………....8 3.6 Building the bonfire………………………………………………8 3.7 Firing the pots…………………………………………………….9 3.8 Studying the remainder of the clays for inclusions………………10 4.0 Results……………………………………………………………………11 4.1 Pots……………………………………………………………….11 4.2 Shrinkage Bars……………………………………………………12 5.0 Comparisons with Chewton Mendip Pottery Fabric Type Series………..13 6.0 Discussion………………………………………………………………..15 7.0 Conclusions and Questions arising from our experiments………………16 8.0 Recommendations………………………………………………………. 16 9.0 Acknowledgments………………………………………………………..16 10.0 References………………………………………………………………17 11.0 Copyright Statement……………………………………………………17

3 1.0 Background to Project A field adjacent to the parish church of St Mary Magdalene in the village of Chewton Mendip, Somerset, has been the subject of investigation by members of Community Archaeology on the Mendip Plateau (CAMP) over the past 8 years. Excavations have taken place twice yearly and much evidence has been gathered to support the theory that this was once the site of Saxon artisan activity in connection with a Minster church. Shortly after the Norman Conquest of 1066, the church lands were granted to the Abbey of Jumièges, Normandy, by William the Conqueror. Extensive stone foundations of a multi-phase building cut the artisan soils, and together provide a potential source of evidence of day-to-day living during that period.

Much medieval pottery has been recovered during excavation and is thought to date from Saxon times through to the early 15th Century. Such is the importance and interest in this pottery, a Medieval Pottery Fabric Type Series is at present being constructed, comprising some 90 different fabrics (Fig. 1). The majority is of coarseware, with some glazed sherds mainly from kilns at Ham Green and Bristol. The project, being run by members of CAMP, forms a major part of a wider study led by pottery expert David Dawson, assessing whether vessels were manufactured on or near to the site, using local clays, or imported from further afield.

This Report details the processes involved in the execution of this experimental archaeology project.

Figure 1 Chewton Mendip Pottery Fabric Type Series (part of)

4 2.0 Rationale for Project Glazed pottery of the medieval period has been the subject of study amongst archaeologists over many decades. Kiln sites such as at Ham Green and Redcliff, Bristol and their associated pottery are well documented (Barton, K.J. 1963) (Dawson, D. & Ponsford, M. 2018) However, coarsewares, the everyday vessels of medieval daily life, and of a more utilitarian nature, have not attracted the same interest. The multitude of fabric characteristics, often differing from site to site within a fairly small radius, makes identifying its place of origin very problematic. The main considerations are the clays which make up the matrix of the pots and the inclusions within them, albeit naturally occurring or added by the potter. There is a long-standing belief that different clays behave in different ways and can benefit from the addition of things like quartz, crushed stone, flint, shell, crushed pot (grog) and other additives in order to prevent shrinkage and cracking during firing.

Figure 2 Ham Green B ware from Figure 3 Coarseware Type 31 from Chewton Mendip Excavations Chewton Mendip Excavations

The variety of different types of clay occurring naturally within the village of Chewton Mendip offers an ideal opportunity for experimental archaeology, to attempt to replicate at least some of the fabrics in the Type Series, using locally sourced materials and firing the vessels in a bonfire for authenticity. With clays collected from around the village during excavations, and inclusions gathered from the bed of the River Chew and other sources, member Jennifer Waters has made a number of similar sized vessels, using different combinations of materials. Once fired, some of the pots were broken and studied under a microscope to look for similarities with our Chewton Fabric Type Series. 5 3.0 Methodology It was decided to attempt to replicate the type of pottery made on a slow, hand turned wheel and fired in a bonfire.

3.1 Gathering clays, silts and other inclusions. Three types of clay were gathered during test-pitting in the village in the Spring of 2018 as follows: Clay 1 Excavation Field: White Lias Formation (pale brown, highly plastic, slightly silty clay with rare sand. Clay 2 Woodside, Lower St: Alluvium (dark brownish-grey, highly plastic with rare silt and fine sand. Probably associated with river deposits) Clay 3 Twyn House, Lower St. Rhaetic, (pale greenish-grey, extremely plastic, very slightly silty clay) Some clay was reserved for study of its naturally occurring inclusions.

Additional inclusions were gathered from:  Spring head of River Chew, centre of Chewton ST600531  Twenty metres downstream from the Spring head  River Chew at Ford ST593536

These were found to comprise quartz, limestone, magnetic fragments and other unidentified particles (see figure 4). Shell and flint was also used (see 3.2.1)

3.2 Preparing the clays Step 1. The clays were kept separate and broken into pieces to remove larger stones and allowed to dry totally. Step 2. The clays were immersed in sufficient water to make a stirring consistency, then vigorously agitated and allowed to settle and excess water to evaporate. Step 3. The clays were kneaded thoroughly to a workable consistency.

3.3 Preparing the inclusions from the River Chew silts Step 1. The gathered inclusions were initially sifted using geological grade sieves of 200-300 and 300-600µm sizes, then dried and bagged.

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Figure 4 The graded, sieved sands from the River Chew bed

The fired-cracked flint was donated by Martin Green from an Iron Age excavation site at Down Farm, Cranborne Chase, Dorset. The land shell was gathered from the Mendip Hills and from the Somerset levels. All was crushed to fine particles.

3.4 Making the pots and bars The pots, of jar form, were made by hand on a slow wheel, comprising 9 pots of various combinations of clays and inclusion and one duplicate. These are detailed in Table 1 below

Pot number 1 2 3 + 4 5 6 7 8 9 duplicate Clay source Clay 1 Dig field lower layer √

Clay 1 upper layer √ Clay 1 combined √ √ layers Clay 2 Woodside √ √ Clay 3 Twyn House √ √ √ Inclusions None √ √ √ √ √ Incl. flint and shell √ √ Incl. 200-600µm √ √

NB. Pots 1 & 2. It was postulated that clay may vary vertically in any one location with the topmost layer differing with regards to frequency and type of inclusions. An attempt was made to mimic this by mixing the clay with a lot of water and leaving it

7 to settle naturally. A pot was then made with the top layer and one with the bottom layer. Pots 6 & 9. It can be assumed that any added inclusions would be introduced at the clay mixing stage. In our observations we have noted that these can be poorly distributed across the matrix and in these pots we have attempted to replicate this by insufficient mixing.

Nine shrinkage gauge bars were made corresponding to each of the pots. These were marked with a 10cm incision to measure the shrinkage rate.

Figure 5 Shrinkage bars before firing nos. 1-6

3.5 Drying process The pots and bars were allowed to dry naturally under cover for several weeks until judged ready for firing.

3.6 Building the bonfire Tree wood was collected for the main wigwam frame with other offcuts of wood donated for the process. The pots and bars were placed 3 over 7 in a bed of hay, on a level layer of wooden slats above a foundation of tree branches. They were then covered in hay and a wigwam built up around them to a height of approximately 0.75m.

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Figure 6 The pots and bars form base of bonfire

3.7 Firing the pots The fire was lit in several places around the perimeter to allow for a gradual heating of the pots. An intense heat was reached in about 10 minutes from lighting and the fire allowed to die down gradually before retrieval of the surviving pots. The whole process took less than an hour. At the height of the fire the core would be starved of oxygen, causing the process of reduction to take place, resulting in a dark grey or black core to the pot. On dying down, the pot is once again exposed to oxygen causing an element of re-absorption of oxygen or re-oxidisation to the pot surface to take place which turns it a reddish -brown colour.

Figure 7 The bonfire taking hold

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Figure 8 The pots emerging as the fire dies down with re-oxidisation taking place

3.8 Studying the remainder of the clays for inclusions. Reserved samples of the clays from the Dig Field and Woodside were finely sieved (425micron) to remove naturally occurring inclusions which were studied under the microscope in the post-experiment stage. This process was very informative in disclosing what inclusions occur naturally in the clay that have been observed in the Chewton pottery (see 5.1)

10 4.0 Results

4.1 Pots Seven pots survived the firing process. Of the three pots which didn’t survive, all were of Rhaetic clay from Twyn House. One left an intact base, the others two shattered into small pieces. Of the fully intact pots there were varying degrees of cracking as described below. Blackening of the sherd surface was apparent on all pots.

Pot number Clay behaviour during firing 1 Horizontal cracks within thicker base. Hairline cracks across base 2 A few vertical cracks and one horizontal 3 Radiating cracks from larger inclusions occurring naturally. Hairline cracks in various plains. 4 One small crack across base 5 One horizontal crack on side and two across base. 6 Three vertical cracks.

Figure 9 The pots after firing. Top row 1,3,5, duplicate), bottom row 2,4,6

The spare DF3 pot was broken to study the section in the conventional way. NB No added inclusions to this fabric. It can be described as follows: Core colour dark grey, exterior colour orange buff, interior colour brown buff.

11 Break irregular. External surface feel, rough. Internal surface feel, rough. Inclusions (microscope @ x10) quartz sparse, quartzite clusters sparse, flint (dark grey) sparse, rounded bog iron resembling pebbles and magnetic moderate. Shiny particles, unidentified. Fossil, sparse. (See figs 11 & 12 for section photos)

4.2 Shrinkage Bars Of the nine shrinkage bars fired, six survived, corresponding to the intact pots. All were marked with an incised 100mm line before the drying process proceeded.

Bar/pot Incision length after firing % rate of shrinkage number 1 900mm 10% 2 850mm 15% 3 900mm 10% 4 900mm 10% 5 870mm 13% 6 900mm 10%

There appeared to be little correlation between the shrinkage rates and whether there were added inclusions to the clay.

Figure 10 The shrinkage bars after firing

12 5.0 Comparisons with Chewton Mendip Pottery Fabric Type Series. Of the surviving bars, 6 were broken and their sections studied under the microscope. The following observations were made. Bar/pot no. Core colour Reoxidised Naturally occurring inclusions & site 1 (DF) Dark grey Yes Sparse angular quartz. Round pebbles. Sparkly particles, shell? Ochre/hematite, Chert 2 (DF) Black Slight Jet black shiny strip-like magnetic particles . Magnesian limestone, sparse lias limestone 3 (DF) Dark grey Some Ditto above + brown magnetic ball 4 (DF) * Dark grey Some Stones, Quartz, Hematite. Sponge-like and coral-like particles. 5 (W) Dark grey Some Frequent lias limestone, Black particles optically same as DF 2 6 (W) Mid to dark grey Some Unevenly distributed bright white speckly appearance. Sparse yellowy-cream lias limestone. * On applying limescale remover to the broken section there was a release of hydrogen sulphide. This did not happen in the other Dig Field sections nor when applied to the silts which were used as additives. We do not know the cause.

The most remarkable similarity between the experimental pots and the those in the Chewton Fabric Series was with DF3 and Type 18. Whilst the break was slightly more irregular in type 18, on filing both sherds down the match was strikingly similar, leading us to believe that there was a strong possibility that clay from the Minster site had indeed been used to make pottery many centuries ago. However, caution must be exercised in jumping to conclusions as it could be that the lias clays across a much wider area have a very closely matching matrix.

Figure 11 Dig Field 3 and Type 18 unfiled Figure 12 The same sherds filed

13 Microscopic study of the inclusions naturally occurring in the clays from both the Dig Field and Woodside, confirmed that certain particles such as fossils, coral, metallic elements and minute pebbles, some of which were magnetic, are the signature of the clays, in addition to the more obvious quartz and limestone and therefore cannot be considered as additives by potters. These have widely been observed in the Chewton Fabric Series.

Figure 13 Naturally occurring inclusions from the Dig Field clays, amongst them, coral, quartz, limestone and other stones

Figure 14 Naturally occurring inclusion from the Woodside clays which includes magnetic particles showing as black.

14 6.0 Discussion This experiment was deemed to be a worthwhile and informative exercise. It gave us considerable insight into medieval pottery making and firing at a time concurrent with at least some of our Fabric Type Series. It was interesting to observe how the clays behaved in the firing process. It was felt that perhaps our pots were fired at too high a temperature, for too long and with too rapid a rise in heat at the start, causing a complete reduction to take place in the core of the fabric. We also believe that we were too hasty removing the pots from the embers and this may have affected the re-oxidisation process. It was also noted that generally the matrix was of an even texture, without lamination, vesicules and the waviness often present in the Chewton Series. Although very limited re-oxidisation took place during the firing process, all the pots had patchy blackening both internally and externally. This serves as a reminder that not all blackened sherds were the result of use as cooking pots. We not only gained a much better understanding of the clays themselves, but also of the inclusions within the fabrics. By carrying out a methodical and detailed experiment, logging every process as we progressed, we were able to draw conclusions about the nature of the Chewton clays. By isolating naturally occurring inclusions we could immediately identify those which we had previously been noted within the Chewton Fabric Type Series thus gaining a much deeper understanding of their composition. This will aid us in inclusion recognition in the future. The complete reduction in the firing to produce a dark grey to black core also indicated iron-rich fabrics and this could be a further source of comparison of the behaviour of our Chewton clays and those in the Chewton Fabric Series. Attention can now be paid to those sherds in the Chewton Fabric series which do not have the above attributes, or which have inclusions not naturally occurring in this region.

15 7.0 Conclusions and Questions arising from our Experiments. This experiment has opened up the possibility of natural clays having been sourced local to the excavation site and processed by local inhabitants. This further begs the question of whether pot making was an artisan activity by one or a few skilled potters, or whether it was more family-based with skills being passed down through the generation. This leads us to question where else local clays may have been obtained and whether certain ‘rights’ were attached to potters or land as in other commodities ie meadow, pasture, woodland in medieval times. CAMP’s study of the Medieval strip farming of Hollowmarsh and its ancient origins showed that many landholdings in Chewton and neighbouring manors had land on the Marsh and that clay is readily available there. The sources and signatures of clay matrices is a wider subject than can be addressed at present, but may have the potential to afford a deeper understanding of the Chewton Pottery.

8.0 Recommendations As some of the clays were retained it would be interesting to repeat this experiment but with a shorter firing time, to a lower temperature and using less fuel. We also intend to make hand-built pots by differing methods to try and mimic the lamination, wavyness and uneven textures of some of the Chewton Series associated with the Saxon period. It is also intended to extend the gathering of clays to outside Chewton and to include these in the next phase of the experiment.

9.0 Acknowledgments CAMP would like to thank the following people for their support Mr and Mrs Lott, John Croxford and Mr and Mrs Gosland for clay samples. Mr and Mrs Pullen for use of their garden for the bonfire Martin Green of Down Farm, Cranborne Chase, for supply of fire-cracked flint David Dawson for his continued support and guidance in all pottery matters Brian Irwin for photography Kay Boreland and Gareth Thomas for expert advice of all things geological

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10.0 References Barton, K.J. 1963. A medieval pottery kiln at Ham Green, Bristol. Transactions of the Bristol and Gloucestershire Archaeological Society 82, 95-126 Dawson, D. & Ponsford, M. 2018. Excavations at Redcliff Hill, Bristol, 1970. Bristol and Avon Archaeology 27, 49-81. Dawson, D.P., Jackson, R.G. & Ponsford, M.W. 1972. Medieval kiln wasters from St. Peter’s Church, Bristol. Transactions of the Bristol and Gloucestershire Archaeological Society 91, 159-167

11.0 Copyright Statement Pip Osborne and CAMP retain full copyright of this, and any other report (commissioned or otherwise), or other project documentation by her under the Copyright Designs and Patents Act 1988 with all rights reserved. Pip Osborne and CAMP may however, assign copyright of a document to an interested party upon written request, but will still retain the right to be identified as the author of the document as defined in the Copyright Designs and Patents Act 1988 (Chapter IV s.79). Please contact through the CAMP website in the first instant. www.camplat.btck.co.uk/contact

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