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Tuesday 13 August 2019

First chapter of my dissertation.2014.


The thermal resistance of crushed angular vein quartz tempered pottery, during firing, with reference to early British, Southwest, Neolithic pottery.
An experimental approach.




                                     SUBTITLE: Making Pots that Fail.





Student number 570000053





‘The presence of objects in the archaeological record infers tools, materials and processes of manufacture’ Giovanna Fregni (Unpublished PhD thesis. The Compleat Metalsmith pers.comm).

CONTENTS 
Title page……………………………………………………………………………………..…....1
Abstract…………………………………………………………………………….….………..….4
Declaration page…………………………………………………………………………….…..5
Acknowledgement page………………………………………….………………………...…6
Biographical  page………………………………………………….………………………..…..7
List of figures………………………………………………………………………………………9
List of tables……………………………………………………………………….……………..32

Chapter 1.   Introduction……………………………………………..……………………….14
   
I-        Aims of the project…………………………………………………….….15
II-      Variability and material cultural perspectives ………………….…18
III-    Chronology and distribution……………………………………….…..19
IV-   Questions………………………………………………………………….…19
V-     How will I carry out this project…………………………………..……21



Chapter 2.  Neolithic pottery, pottery studies, theory and materiality…………24

I.                    Prehistory and the study of the Neolithic…………………………….....24
II.                   Material Culture………………………………………………………………...27
III.                Technological advantages of Ceramic vessels……………………..…..30

Chapter 3.  British Neolithic Pottery and the southwest tradition……………….32
I.                    Problems and issues……………………………………………………….33
              II              Form……………………………………………………………………………38
             III              Southwest Neolithic pottery……………………………………………39

Chapter 4.   Large angular crushed vein quartz tempered Neolithic Pottery…43


Chapter 5.   Clays and soils of Devon…………………………………………………….. 48
I.                      Sampling the clays, sands and quartz………………………………48

Chapter  6.    Ethnographic evidence for materials choices and selection and experimentation…………………………………………………………………………………53

Chapter  7.   Thermal shock resistance, fracture mechanics and the design of an archaeological experiment in crack formation………………………………………..…55
I.                    Mechanical theories of thermal shock resistance …………………….…55

Chapter 8.  Experimentation, archaeology and ceramics………………………….…60
I.                    Which clay is to be used?...................................................................62
II.                  Field or lab experiments?...................................................................62
III.                Choosing form and forming technique………………………………………63


Chapter 9. Experimental Methodology………………………………………………….…65
I.                    Materials processing……………………………………………………………...66
II.                  Forming methods……………………………………………………………….…67
III.                Firing methods………………………………………………………………….….69
IV.               Phase 1, 2 and 3, clay paste recipe variation by dry weight. ……….…75
V.                 Crack analysis and quantities per pot. ………………………………………76

Chapter 10. Crack mechanics, analysis,  results and discussion………………….…79
I.                    Crack analysis tool……………………………………………………………..…79
II.                  Crack quantification …………………………………………………………..…84
Chapter 11.  Conclusion…………………………………………………………………………89
Future directions………………………………………………………………………………….91
Appendices …………………………………………………………………………………………95
I.                    Clay sampling in Devon Appendix II …………………………………………95
II.                  Email from Roger Taylor discussing sourcing river greensand……….96
III.                 Coefficients of expansion of raw materials………………………………..97


Bibliography……………………………………………………………………………………….102





Abstract
 This paper presents a recently designated early, regional Neolithic pottery fabric from southwest Britain, restricted to Devon and Cornwall. The period it represents is the Mesolithic-Neolithic transition.    This fabric, which has been called large angular crushed vein quartz tempered pottery, has early C14 dates associated it and is found in the whole range of early Neolithic contexts. It is found in large quantities at Hembury and Raddon causewayed enclosures.  One of the issues of incorporating large pieces of temper in pottery is whether it is acting as a thermally resistant material or whether it may have had a symbolic significance, over and above a purely technological function.   If it would be possible to establish whether  or not these inclusions are an effective temper or not, i.e. prevent the pots from cracking whilst being fired then, it may be possible to draw some conclusions or at least offer a tentative interpretations.
Using an experimental methodology designed by myself, based on producing and quantifying cracks in pottery, correlating the data to differing clay paste recipes, containing Upper Greensand sand and large crushed angular vein quartz, the aim is to confirm or suggest that the LACVQT is not an adequate thermally resistant material.  The pottery was fired in three bonfires.
The paper and project also considers the wider archaeological questions of distribution, the possibility of exploring the production and whole chaîne opératoire of British southwest Neolithic pottery experimentally.


 Chapter 1

INTRODUCTION


Neolithic pottery of the Southwest ‘Hembury, plain,  bowl ’ tradition (Whittle 1977),   has largely been characterised by the Hembury bowl in Exeter’s Royal Albert Memorial Museum and ground-breaking work, into the petrography of the pottery made from gabbroic clay from Lizard, Cornwall (Peacock, 1969a,1988). However, Neolithic pottery assemblages in East Devon contain only small quantities of gabbro clay pottery, as illustrated by the quantification and inclusion map, Fig 4, below, (Quinnell and Taylor, forthcoming).  Whilst quantifying the making marks, forms and fabrics from the pottery assemblages from Hembury,  High Peak, Hazard Hill, Haldon House , for the purposes of this  MA Dissertation,  it became obvious that out of several general pottery fabrics present in these assemblages, there were large proportions of large angular, crushed vein quartz tempered pottery(LACVQTP), see Frontispiece as an illustration.  The inclusions of this pottery can reach up to one centimetre in size or bigger, see Figs. 5 and 6 below, and are always angular, therefore it is inferred that they were crushed by hand. They are also large enough that they protrude out of the surfaces of the pottery at times, see Fig 8 below. The maps Fig 4 and Fig 7 illustrate the wide distribution of this pottery type across the region. Subsequent conversations with both Henrietta Quinnell and Roger Taylor of Exeter Museum, confirmed that this was a widespread early Neolithic Pottery (ENP) fabric.

Quinnell and Taylor have carried out a systematic quantification of all Neolithic pottery assemblages in the region, producing statistics and a map, Fig 4. of the distribution of early southwest fabrics by quantifying relative percentages for each site assemblage by weight and sherd counts (Orton, 1993).  Dorothy Liddell who excavated Hembury Hillfort, in the 1930’s (Liddell, 1930, 1931, 1932, 1935), discovering the Neolithic causewayed enclosure in the process, never completed a definitive report due to her death in 1938.  At Hembury Causewayed Enclosure, the percentage of large angular crushed vein quartz tempered pottery is fifty percent and at Raddon Hill enclosure, eighty one percent, (Gent and Quinnell 1999, Quinnell and Taylor, Forthcoming).


I.                    Aims of the project
The aims for studying this pottery fabric  is to explore in some detail this regional  southwest, early Neolithic pottery fabric, introducing the variability of  ESWNP  as  emphasis has been on gabbro pottery, mostly in the wider literature of the southwest British Neolithic.(Thomas 1992, Cleal, 1992, 1995, 2004. Darvill, 1987).  Additionally, the picture becomes more complex as LACVQT was added to gabbroic clay in Cornwall for example, at Carn Brea, see Fig.7 map for the regional distribution.  LANCVQP got a mention in the wider literature (Whittle et al, 2011) in Gathering Time.   Early southwest Neolithic potters were producing a highly variable range of pottery, using local clays and tempers, not just transporting gabbro clay to Hembury and Windmill Hill. Unfortunately the general literature of the early southwest British Neolithic might give the impression that this was the sole ceramic activity.  Since studying the pottery in the RAMM, it became obvious that pottery fabrics were more complex than I had originally anticipated.   Local excavation reports in Cornish Archaeology and Proceedings of the Devon Archaeological Society also confirm this.   It is remarkable, that although this pottery was found at Hembury in the 1930’s, in obviously large quantities that it had escaped notice, especially, as it has been found consistently across the region.  It wasn’t until the Carn Brea report, in 1986, which systematically categorised form, fabric and typologies that the fabric was remarked on.  This type of pottery is rare. It is highly distinctive and it is very unusual for potters to include such large inclusions in pottery, at all (unless they are making crucibles or bricks).  Indeed, more LACVQP has been found recently on excavations of a multi-period site, run by Exeter University, Department of Archaeology, in Neolithic pits at Ipplepen, Devon (Pers. comm. Quinnell and Imogen Wood).   A second aim is to attempt to focus on this particularly distinctive Neolithic southwest fabric using an experimental approach to re-enact/reconstruct a proposed Chaîne Opératoire of its production and to focus into one aspect of this Chaîne opératoire - the thermal resistance of this particular type of temper, large angular crushed vein quartz.   In doing so, a macroscopic  methodology will be used  (Hurcombe 2008) to assess the effect of firing this pottery in a bonfire quantifying  the cracks produced in pottery so that the thermal resistance of a particular temper can be measured in a quantifiable, verifiable and repeatable manner. Correlates between crack production and differing clay and temper recipes will be made.   A third  aim, is to explore the early southwest Neolithic using this detailed focus  gained from pottery studies using a technological systems approach, using experiments in ceramic production, bearing in mind that the presence of objects in the archaeological record infers  the use of tools, materials and processes of manufacture.  The focus will be on the British, southwest, early, Neolithic potter as an agent of action within her landscape (Louwe Koojimans, 2010, Thomas 2013). It is not the aim of this study to explore gendered archaeology, but potters will be referred to in the feminine as the author is feminine and the literature now supports this acknowledgment.    The main objective of this project is to determine whether large angular crushed vein quartz on its own in pottery is an adequate tempering material.  Tempers in pottery are the thermally resistant materials, that is, tempers in adequate quantities prevent cracking in an open fire.

An initial aim of this project was to attempt to locate the clays that these pots were made from; however, this has not been possible due to time and skill restraints. A sampling program was carried out in April 2014, where likely sources of clays and tempers were located. See Appendix 1. Some of these have been used within the project.

On examining the LACVQP, questions arise as to whether this temper was thermally resistant to firing in a bonfire? Other questions that have been posed are whether the quartz was fire treated prior to crushing, (Quinnell and Taylor, forthcoming)?   Quartz firing experiments were carried out by this author prior to commencing the work for this dissertation and as a result produced enough crushed angular quartz to run the experiments. 

II.                 Variability and material cultural perspectives
As mentioned above, it has been observed that the variability of these early Neolithic pottery fabrics is high both in fabric composition and in combination with the vessel forms.   An  examination of the sherds shows consistently differing  manipulation of raw materials. Moreover, not only was LACVQT added to local clays in Devon and Cornwall but  it  was also being added to  gabbro clay on some sites in Cornwall, notably Penmayne(Gossip et al, forthcoming),  Gear(Edwards and Kirkham, 2008), and Church Close, Mitchell, (Quinnell and Taylor 2004), and at Carn Brea( Smith and Soffranoff, 1986). Table 1 below also shows eight variants from Raddon enclosure of what is a local variant fabric of a regional fabric. As well as moving  gabbro clay from the Lizard, to the sites where the pots were to be made, to far flung parts of the British Isles, as far as Wiltshire,  they were making pots from clay pastes/fabrics from varyingly  locally sourced  clays.  Out of forty sites in Devon and Cornwall (Quinell and Taylor, forthcoming) listed in the gazetteer, LCAVQTP occurs on twenty-three sites. Another variant is Broadsands pottery which may have been made from estuarine clay.

)
Table.1. variants of vein quartz fabrics from Raddon enclosure excavation, Pottery report, showing that out of one regional fabric of LACVQTP, there are at least eight variants (Gent and Quinnell, 1999, 39-43)


My sampling of estuarine sediments has been unsuccessful as regards general plasticity of the materials. The best so far has been from Budleigh Salterton.  They state that the Raddon pottery was likely to have been made from the carboniferous clays and Permian breccia, weathering products (clays) local to the site.  The high variability of archaeological artefacts was a processualist/behaviourist assignment (Skibo and Schiffer, 1997) and currently now has to be reconsidered in the light of this new evidence of artefact variability.  Indeed, an elegant description of style (Wobst (1977, 321,) as being ‘a formal variability in material culture’s participation of information exchange’ could be re-used within this scheme.
Early British Neolithic pottery is significant as it is the first functional pottery to be made and used in the British Isles and represents the ceramisation (Vanmontfort 2012) of the British Isles with implications of social restructuring during the Mesolithic-Neolithic transition.  New approaches  (Robb 2013), on  the role material culture, such as  larger aggregation behaviours, revolving around material cultural elements circulating  within the contexts of causewayed enclosures would have been socially beneficial to the people of the Neolithic- Mesolithic transition are beginning to emerge.  If LACVQTP is considered within this theoretical framework new perspectives on the early Neolithic maybe possible where people and their interactions with objects which make up the archaeological record, (Webmoor, 2007). There is not the scope in this essay to explore these theoretical issues at this point in time.

III.Chronology and distribution.
One of the most crucial aspects of studying the Neolithic is the use of C14 dating. It is necessary to refer to Gathering Time: Dating the early Neolithic Enclosures in Southern Britain and Ireland (Whittle et al, 2011)...  The Bayesian recalibration of older C14 dates highlighted the errors that had accrued in chronologies and pushed back the start of the Neolithic by between 1000-2000 years.  The period under consideration in this dissertation is in a range of two to three hundred years. The pottery is associated with causewayed enclosures, Tor enclosures, timbered buildings, pits, ditches and other find spots and is spread across the region from Hembury in the east and to Gear, nr Helston, Cornwall, see fig. 7 below for a breakdown of site types.     
One of the earliest dates for the period is from Broadsands chambered tomb, nr Torquay, (Sheridan et al, 2008), at 3940cal BC- and there are a few sherds of quartz tempered pottery associated with the human remains in the tomb. Hembury and Helman Tor, have the earliest C14 dates for enclosures in the region and were being constructed approximately 370cal BC. The C14 dates from Hembury were from residues on ceramic and Helman Tor from charcoal. (Whittle et al 2011).  C14 dates for Raddon are based on charcoal samples and the enclosure was likely in use for only a hundred years (Whittle et al 2011). 

III.Questions
This section is an organic process of attempting to ask questions in a brainstorming process trying to generate questions after an object analysis where affordances of various pottery types have been included into the chaîne opératoire approach.  The types of questions that are generated are multiple overlapping and will develop into socio-cultural and theoretically significant questions. The types of questions that can be asked are why were the Neolithic potters using large crushed angular vein quartz when there other readily available sources of vein quartz tempering materials in the environment, which contained smaller river, rounded grains of quartz? Indeed prospection for materials from the region has shown that pebbles of one centimetre or less are present in river sands. There is quartz in the Upper Greensand sand from the region and from the granites of the region.  Was the large size of the inclusions significant for reasons other than for tempering? Where did the clay come from?  Is large crushed angular quartz on its own an adequate temper material? How did the Neolithic potters make these pots?  How did they break up their quartz?  Did they fire treat it prior to smashing it? Does this pottery represent one group of potters in the region?  Were the gabbro potters a different school/tradition of potters?  Were they in competition with the gabbro potters? The gabbro pots were finely finished pots(I have not looked at the Carn Brea or other Cornish assemblages, in person,  but the picture  the Cornish assemblages present is a completely different  scenario to the Devon picture(pers. comm, Henrietta Quinnell)  thinly made  with extremely smooth surfaces and very even rims. The quartz tempered pottery had uneven rims and were roughly finished with making marks left obviously all over the surfaces.  Fig.15 is  an image of a complete Neolithic pot, the Balfarg pot, showing the uneven rim and evidence of making marks, but evidence of making marks are also found on sherds from Hembury, frontispiece,  and figs 2, 3, 4, 6 and 24.  There is huge difference in the visual appearances of these pots. What is the significance of this in an embryonic ceramic tradition?  Were the same potters producing the different kinds of pots?  Were the roughly made pots, the pots of the ‘learner potters? Were the gabbro bowls the pinnacle and the highest expression of the craft?  Was the quartz tempered pottery made earlier or later in the period than other clay paste recipes? No practical work has been done on the sourcing of the clays from the region, as yet. Were the clays used to make this fabric all sourced locally and if so what does this mean for the ESWN?  Does the use of another clay fabric from the Southwest represent a particular group of Neolithic potters? Does the use of the gabbro represent one group of potters? If not, were all the potters using all the clays/fabric recipes from the region? It is likely that as the pottery is highly variable that the scenario is not as simple as this.   Is QTP contemporaneous with the other fabrics or are we seeing a sequential use of different clay fabrics?  If answers are attempted to these questions they produce different possibilities of interpretations. And will be dealt with in the discussion and conclusion. Where fabrics are found together in sealed well dated contexts we have to assume that they are contemporaneous, refs.  The alignment of a chaîne opératoire approach with a focus on fabric analysis may produce multiple questions which may not be answerable in the immediate future but broadens the scope for research into the field of the early British Neolithic.
These types of question also focus on an aspect of locating the individual/potter in a time slot which will provide an opportunity to theorise using agency theory approaches to the early British southwest Neolithic and the Mesolithic-Neolithic transition. .

I.                    How will I carry out the project?






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