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(Unpublished PhD thesis.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.
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?
