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155
XIII/2/2022
INTERDISCIPLINARIA ARCHAEOLOGICA
NATURAL SCIENCES IN ARCHAEOLOGY
homepage: http://www.iansa.eu
Petro-Archaeometric Study of Pre-Roman Pottery from the Archaeological
Site of Bec Berciassa (Roccavione, Cuneo, North-West Italy):
Technological Remarks from Petrographic Study of Tempers
Maria Pia Riccardi
1,2*
, Deneb Cesana
3
, Maya Musa
1
, Sergio Martini
4
, Francesco Zucca
1
1
DSTA – Università degli Studi di Pavia, via A. Ferrata 9, I27100, Pavia, Italy
2
Laboratorio Arvedi, sede di Pavia, via A. Ferrata 9, I27100, Pavia, Italy
3
Soprintendenza Archeologia Belle Arti e Paesaggio per le province di Alessandria, Asti e Cuneo, Cittadella – via Pavia snc, I15121, Alessandra, Italy
4
Fondazione “La Pietra Lesa”, via Olmazzo 42, I27040, Mornico Losana, Italy
1. Introduction
The Bec Berciassa archaeological site is the most important
protohistoric settlement in the Maritime Alps, Cuneo district.
It is situated at the confuence of the Gesso and Vermenagna
rivers, at 692 metres asl (Figure 1), overlooking the
surrounding valleys and lying along transalpine routes that
have been used since the late prehistoric period. Before the
region was Romanised in the 2
nd
century BC, this hill had
long been occupied by the ancient Ligurian tribes from the
Late Bronze Age 1550–1200 BC.
The discovery of the archaeological site dates back to 1931,
when Rittatore Vonwiller identifed and excavated the traces
of a “prehistoric village” (Rittatore Vonwiller, 1952). The
relevance of the archaeological site for the reconstruction
of the history of the territory and its valorisation has been
supported by the studies carried out in following years by
the Soprintendenza Archeologica del Piemonte (Ferrero,
and Venturino Gambari, 2008) and the very recent survey
and excavation campaigns (2017–2019) promoted by the
Municipality of Roccavione (Cuneo) (Cesana
et al.
, 2018;
Rocchietti and Cesana, 2018, Cesana and Padovan, 2019).
The study of the pottery individuates an older phase
dating back to the Late Bronze Age represented by a small
sample of ceramics. At the same time, the chronology of
most of this material is homogeneously ascribable to
a period between the 6
th
and the beginning of the 4
th
century
BC (Iron Age).
Volume XIII ● Issue 2/2022 ● Pages 155–162
*Corresponding author. E-mail: mariapia.riccardi@unipv.it
ARTICLE INFO
Article history:
Received: 21
st
March 2022
Accepted: 8
th
August 2022
DOI: http://dx.doi.org/10.24916/iansa.2022.2.5
Key words:
ceramics
Pre-roman production
northern Italy
raw materials
production technology
petrography
ABSTRACT
The petro-archaeometric study of ceramics from the Rittatore excavations, Bec Berciassa archaeological
site, was carried out on pottery sherds attributed to an older phase dating back to the Late Bronze Age.
This collection represents a small sampling of pottery and the chronology of most of this material is
homogeneously ascribable to a period between the 6
th
and the beginning of the 4
th
century BC (Iron
Age). In addition to the archaeometric study, a geological survey highlighted the resources of the area
potentially useful for the development of prehistoric communities, including resources that could be
used for ceramic production.
A thin section study under optical microscope distinguished fve ceramic mixtures. They are mostly
coarse-grained, hiatal, and serial-textured, calibrated with the addition of fllers. The fne matrix is
homogeneous in composition, although with compositional variations in Fe
2
O
3
. Therefore, it is
possible to hypothesise a single source of supply. The diferent types of fller can be traced back to
minerals and rocks found outcropping within the basins of the Gesso and Vermenagna rivers and thus
potentially present as pebbles in their beds. Calc-schists, sparitic calcite, magmatic rocks (granites and
aplites), and sericite-schists have been used since the Bronze Age; quartz sandstones and quartzites
are only present in Iron Age pottery. At a macroscopic level, all these fller agents are light in colour,
tending to white, almost as if the colour and homogeneity of the geological material were a criterion
of choice dictated more by tradition and know-how rather than by any particular technological choice.
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IANSA 2022 ● XIII/2 ● 155–162
Maria Pia Riccardi, Deneb Cesana, Maya Musa, Sergio Martini, Francesco Zucca: Petro-Archaeometric Study of Pre-Roman Pottery from the Archaeological Site of
Bec Berciassa (Roccavione, Cuneo, North-West Italy): Technological Remarks from Petrographic Study of Tempers
156
Excavations conducted in 2018 and 2019 unearthed a large
number of pottery pieces, nearly 300, but this preliminary
study focused mainly on historical fnds from the Rittatore
excavations. The ceramic bodies themselves contain
signifcant information about the production technology used
to make them (Maggetti, 1982; Maggetti, 1994; Freestone,
1995; Quinn, 2013; Montana, 2020). Their detailed study,
through a petrographic approach, allows the collection of
information concerning the technology followed for the
realisation of the mixtures: the raw materials that were used
for their production, and where these raw materials were
collected.
In this study, the petrography of the ceramics was
conducted by focusing on the textures of the mixtures and
aiming the petrographic reading toward the coarsest parts of
the mixture,
i.e.
, both the mono- and polymineralic grains.
Quantity, shape, rounding, sorting, and state of conservation
of the grains are textural parameters that, when interpreted
together with the petrography of the grains, allow us to
reconstruct many steps related to the production chain
(Eramo, 2020; Gualtieri, 2020).
To better understand the manufacturing, we have made
a survey of geological materials potentially useful for
the production of ceramics. In the area of interest for the
archaeological site, there is a geological formation known as
“Calc-schists with Green Stones” (or “Calc-schist Complex”
Unit), a unit outcropping that extends over the lower slopes
of the Vermenagna, Stura and Grana Valleys (Montaldo
Calc-schists) and overlaps with that known as Brianzonese
Unit (Ormea Unit). The diferent rocks mentioned condition
strongly and diferently the hydrography, which therefore
difers locally based on the lithotypes encountered by the
water and their location: the hydrographic network has its
maximum development in the outcropping area of schists
(non-porous); correspondingly in the calcareous lithologies
(porous), however, the hydrology reduces above 750 m,
where these lithotypes dominate, and infltration and
an underground circulation prevail, as the surface hydrography
almost disappears. All of this has certainly conditioned the
anthropisation of the site and not only related to the general
conditions of habitability, but especially concerning the
availability of water and the exploitation of raw materials.
The survey and sampling of geological materials are the basis
for establishing technical choices for ceramic production.
Two main archaeological questions drove the goals of this
paper: What was the production technology of the ceramics
of Bec Berciassa? Which raw materials were used?
2. Materials and methods
All samples from the “Rittatore excavations” were analysed
with a lens, using a non-invasive approach. The results of
this frst survey allowed the identifcation of distinct groups
based on the coarse component of the mixture. On this basis,
a selection of fnds, representative of each group, was carried
out to realise petrographic thin sections. A total of 17 thin
sections, polished, were prepared (Table 1).
The polished thin sections were studied under optical
microscopy using an Olympus BX51 UV polarised light
Figure 1.
Location of the Bec Berciassa archaeological site. Points 1, 2 and 3 show the sampling points of the geological raw materials.
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IANSA 2022 ● XIII/2 ● 155–162
Maria Pia Riccardi, Deneb Cesana, Maya Musa, Sergio Martini, Francesco Zucca: Petro-Archaeometric Study of Pre-Roman Pottery from the Archaeological Site of
Bec Berciassa (Roccavione, Cuneo, North-West Italy): Technological Remarks from Petrographic Study of Tempers
157
Table 1.
The table shows the values of the textural and compositional parameters (morphological features and petrography of the rock fragments) of the ceramic bodies. The evaluation was carried out on thin
sections, under an optical microscope. Wentworth class: VCG = very coarse grain, CG = coarse grain, FG = fne grain; sorting: VWS = very well-sorted, WS = well-sorted, MS = moderately-sorted, VPS = very
poorly-sorted, PS = poorly-sorted; roundness: 0.1= very angular, 0.3 = angular, 0.5 = sub-angular, 0.7 = rounded, 0.9 = well-rounded (Krumbein and Sloss, 1963).
SamplesTemper featuresPetrography of grains %
Sample codeAgeDescription
Thickness (cm)
Wentworth class
% (Vol)
Sorting
Krumbein roundness
Magmatic intrusive
Quarzite
Sericitic schists
Calcite / dolomite
Calc-schists
Sandstones
Clay pellets
BBR1bronze age
Rittatore archaeological excavation (1951); ripiani
1
CG
35MS0
.
1
5002050000
BBR2bronze age
Rittatore archaeological excavation (1951); ripiani
0
.
75VCG
10
VPS
0
.
3
80
01000010
BBV1067middle iron age, V B.C.Rittatore archaeological excavation (1951); vigna; bowl
0
.
65
FG
20WS0
.
7
000000100
BBV1063middle iron age, V B.C.Rittatore archaeological excavation (1951); vigna
0
.
58VCG
30
VPS
0
.
1
50
80
00150
BBV1078middle iron age, V B.C.Rittatore archaeological excavation (1951); vigna; bowl
0
.
63
CG
10MS0
.
5
50000095
BBV1075middle iron age, V B.C.Rittatore archaeological excavation (1951); vigna
0
.
83VCG
20
VPS
0
.
1
80
0200000
BBV1017middle iron age, V B.C.Rittatore archaeological excavation (1951); vigna
0
.
84VCG
30
VPS
0
.
1
1010
70
00010
BBV1107middle iron age, V B.C.Rittatore archaeological excavation (1951); vigna
0
.
88VCG
10
VPS
0
.
1
009000010
BBV1070middle iron age, V B.C.Rittatore archaeological excavation (1951); vigna
0
.
68VCG
25
VPS
0
.
1
1010
80
0000
BBR1054 iron age
Rittatore archaeological excavation (1951); ripiani
0
.
78CG
30MS0
.
3
70
00201000
BBR370
iron age
Rittatore archaeological excavation (1951); ripiani
1
.
25
VCG
10
VWS
0
.
1
000010000
BB52 1057
iron age
Rittatore archaeological excavation (1951); ripiani
0
.
75CG
10MS0
.
5
50000095
US22-BB19-43 iron age
2019 excavation campaign
0
.
75VCG
20
VPS
0
.
3
1004005000
US15-BB19-35 iron age
2019 excavation campaign
0
.
75VCG
25
VPS
0
.
1
150100
75
00
US22-BBV2019-32A
iron age
2019 excavation campaign
0
.
55
CG
3OMS0
.
5
20
70
100000
US15-BB19-34 iron age
2019 excavation campaign
0
.
88VCG
30PS0
.
1
2060200000
BB2017 UR134/1
iron age
2017 excavation campaign
1
.
1
VCG
20
VPS
0
.
3
70
02001000
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IANSA 2022 ● XIII/2 ● 155–162
Maria Pia Riccardi, Deneb Cesana, Maya Musa, Sergio Martini, Francesco Zucca: Petro-Archaeometric Study of Pre-Roman Pottery from the Archaeological Site of
Bec Berciassa (Roccavione, Cuneo, North-West Italy): Technological Remarks from Petrographic Study of Tempers
158
(OM) petrographic microscope with Olympus UC30 digital
camera.
The abundance, distribution, and shape of the inclusions
were evaluated by comparative charts, following the protocol
given in Quinn (2013).
A scanning electron microscope with energy dispersive
electron microanalysis (SEM-EDS) was used to study
the matrix. The SEM used was a Tescan FE-SEM
(Mira 3XMU-series), equipped with an EDAX energy-
dispersive spectrometer (silicon drift detector energy-
dispersive X-ray – spectrometer – SDD-EDS). The operating
conditions were: 20 kV accelerating voltage, 12 mA
beam current, 15.8 mm working distance, counts of 100 s
per analysis, and dead time of approximately 25%. The
measurements were processed using the EDAX Genesis
software, and the data was obtained using the ZAF correction.
Samples were prepared by C-coating from graphite (C).
The geo-archaeological survey was extended beyond the
archaeological site and directed to the search for materials
comparable to those found in the ceramic bodies, specifcally
the materials used as fllers. A study was carried out on the
pebbles of the Vermenagna and Gesso rivers, which were
considered potential sources of useful geological material
for the treatment of ceramic soils. In the riverbed near the
archaeological site, the Gesso and Vermenagna rivers still
have a torrential feature. Their recent deposits, and those on
some of the higher terraces of the active riverbed, rarely show
the deposition of sandy deposits. Outcropping sediments are
generally gravels, pebbles, and cobblestones (Figure 2A).
One hundred river pebbles and cobblestones were counted
and catalogued according to rock type. The counting points
are shown in Figure 1: in the Vermenagna stream bed,
upstream of the confuence with the Gesso River (point 2 in
Figure 1), and along the Gesso River (point 3 in Figure 1).
Counting was conducted using a 1 m-sided counting grid,
divided into 10 cm squares. Pebbles corresponding to the
crossing points of the grid rows were collected (Figure 2A).
3. Results
3.1 The pottery fragments
The texture of the artifacts can be defned as hiatal or serial
(Table 1), according to Maggetti (1994). The mixtures
were coarse grained to very coarse grained (Table 1); only
one artifact being fne-grained, despite having a consistent
thickness (BBV1067, in Table 1).
Temper grains are mostly rock fragments; mono-mineral
grains correspond to the same minerals found in rock fragments.
Grains commonly had a low roundness, with indented edges
(roundness between 0.1–0.7), only the grains of metamorphic
rocks having more rounded shapes, particularly sericitic schist
grains, which are rich in sericite, and consequently have a more
plastic behaviour than other grains. The temper ranges from
very poorly sorted to well-sorted (Table 1; Figure 3). Grains
are mainly well-preserved and unaltered. The morphological
features of these grains led to the hypothesis that there had been
an intentional addition of fller to correct the plasticity of the
Figure 2.
Counting and classifcation of pebbles from the Vermenagna and Gesso rivers. A: point counter used for the statistical survey of pebbles; B: most
frequent pebbles in the coarse deposits of the river beds.
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Maria Pia Riccardi, Deneb Cesana, Maya Musa, Sergio Martini, Francesco Zucca: Petro-Archaeometric Study of Pre-Roman Pottery from the Archaeological Site of
Bec Berciassa (Roccavione, Cuneo, North-West Italy): Technological Remarks from Petrographic Study of Tempers
159
clay matrix. In particular, well-preserved grains with angular
shapes, unsorted, represent the result of crushing rocks and
the degree of sorting corresponds to the subsequent process of
a particle size selection of the crushed material. The percentage
of fller varies for each artifact (Figure 3). In Figure 3A, one
temper addition is less than 10% and such a percentage can
Figure 3.
Optical microscopy imagery (PPL = plane-polarised light) of ceramic textures, some examples. A: hiatal texture with temper addition that is less
than 10 %; B: serial texture with temper up to 35 %, with roundness of fragments very low; C and D: hiatal texture with temper approximately 25–25 %.
Figure 4.
Optical microscopy imagery (XPL = cross-polarised light). Petrographic characterisation of the rock grains that form the ceramic temper.
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IANSA 2022 ● XIII/2 ● 155–162
Maria Pia Riccardi, Deneb Cesana, Maya Musa, Sergio Martini, Francesco Zucca: Petro-Archaeometric Study of Pre-Roman Pottery from the Archaeological Site of
Bec Berciassa (Roccavione, Cuneo, North-West Italy): Technological Remarks from Petrographic Study of Tempers
160
have no technical function in the ceramic body because it does
not change the plasticity of the ceramic mixture; on average, the
added fller was found to have percentages ranging from 20%
(Figures 3C and 3D) up to 35% (Figure 3B). Table 1 shows
the distribution of the diferent types of rock fragments in the
ceramic temper.
The most frequent rock fragments are related to magmatic
intrusive rocks (Figures 4A and 4B) and metamorphic rocks
(Figures 4D, 4F and 4G). Among the latter, sericitic schists
(Figures 4F and 4G) and calc-schists (Figure 4D) prevail.
It is difcult to give a precise petrographic classifcation of
the grains because the association of minerals is sometimes
partial. Considering the fragments of magmatic rocks,
the diagnostic character of the hypidiomorphic texture
of intrusive rocks is evident, but it is impossible to make
even a qualitative assessment of the quantity of the minerals
constituting the original rock. It is, however, possible to
detect the partial association of minerals, such as: quartz
+ K-feldspar + biotite ± chlorite, K-feldspar + amphibole
± chlorite, quartz + K-feldspar, quartz + K-feldspar
+ plagioclase + biotite. These types can be traced to the
Argentera Massif, from which the Gesso River originates.
Sericitic schists and calc-schists outcrop extensively in the
hydrographic basin of the two rivers.
Pottery sherds with a mixture containing quartzite
(Figure 4E) or quartz sandstone fragments (Figure 4C)
are less abundant. Only sample BBR1, Bronze Age,
contains a signifcant amount of sparitic calcite fragments
as a fller (Table 1). In ceramic mixtures, diferent rock
fragments are often associated with each other; in fact,
a single-component fller has rarely been observed. The
most common situation shows a dominant lithotype within
the temper (in percentages of more than 50% up to 95%)
associated with small percentages, sometimes only 5%, of
grains of other lithotypes (Table 1). Few artefacts are devoid
of rock fragments (Table 1). In these artefacts, the fller is
represented by clay pellets which have the same composition
as the fne matrix (Table 2). The rock fragments stand for
less than 5% and are represented by intrusive rocks. These
clay pellets, which can sometimes represent 100% of the
non-plastic fraction of the ceramic body, may result from
the use of soil that was originally partially consolidated and
then poorly worked. In these bodies, the texture is serial,
according to Maggetti (1994).
Table 2.
Chemical composition of clay matrix and clay pellets.
SamplesNa
2
OMgOAl
2
O
3
SiO
2
P
2
O
5
K
2
OCaOTiO
2
MnOFe
2
O
3
BBV1017 clay matrix
0
.
42
.
530
.
546
.
51
.
33
.
01
.
40
.
8
0
.
113
.
4
BBV1107 clay matrix
0
.
32
.
624
.
455
.
7
1
.
12
.
41
.
10
.
60
.
311
.
4
BBV1070 clay matrix
0
.
32
.
7
31
.
044
.
11
.
22
.
8
1
.
40
.
8
0
.
415
.
1
BBR1054 clay matrix
1
.
43
.
7
26
.
944
.
51
.
42
.
01
.
20
.
60
.
2
17
.
8
BBV1067 clay matrix
0
.
32
.
429
.
942
.
63
.
42
.
62
.
7
1
.
00
.
114
.
6
BBV1063 clay matrix
0
.
52
.
331
.
444
.
8
2
.
02
.
61
.
7
1
.
10
.
013
.
4
BBR370 clay matrix
0
.
42
.
931
.
644
.
91
.
43
.
21
.
60
.
90
.
112
.
9
BB52 clay matrix
0
.
31
.
933
.
3
38
.
8
3
.
31
.
8
2
.
30
.
8
0
.
1
17
.
0
BBV1078 clay matrix
0
.
32
.
7
26
.
748
.
43
.
52
.
91
.
60
.
7
0
.
013
.
1
BBV1075 clay matrix
0
.
33
.
429
.
942
.
64
.
33
.
41
.
90
.
90
.
113
.
0
US22-BB19-43 clay matrix
0
.
32
.
432
.
440
.
62
.
53
.
61
.
20
.
90
.
016
.
1
US15-BB19-35 clay matrix
0
.
32
.
530
.
643
.
62
.
53
.
11
.
30
.
90
.
114
.
9
BB2017 UR134/1 clay matrix
0
.
52
.
4
28
.
643
.
8
4
.
62
.
33
.
21
.
10
.
213
.
1
BBV1067-1 clay pellets
0
.
22
.
132
.
939
.
33
.
12
.
02
.
10
.
8
0
.
0
17
.
1
BBV1067-2 clay pellets
0
.
21
.
7
32
.
837
.
93
.
7
2
.
02
.
8
0
.
8
0
.
1
17
.
3
BBV1067-3 clay pellets
0
.
21
.
8
32
.
440
.
42
.
12
.
32
.
50
.
90
.
0
17
.
1
BBV1107 clay pellets
0
.
31
.
633
.
4
37
.
53
.
92
.
02
.
60
.
90
.
1
17
.
4
BBV1017 clay pellets
0
.
21
.
8
32
.
240
.
42
.
52
.
22
.
41
.
00
.
1
17
.
1
BB52 1057 caly pellets
0
.
32
.
032
.
4
38
.
63
.
8
2
.
32
.
7
0
.
8
0
.
216
.
8
BBV1078-1 clay pellets
0
.
53
.
021
.
923
.
59
.
8
2
.
5
18
.
30
.
913
.
06
.
5
BBV1078-2 clay pellets
0
.
22
.
225
.
253
.
52
.
7
2
.
91
.
30
.
7
0
.
011
.
1
BBV1078-3 clay pellets
0
.
32
.
430
.
244
.
62
.
03
.
61
.
11
.
20
.
014
.
5
BBR2 clay pellets0
.
7
2
.
7
25
.
543
.
51
.
95
.
7
11
.
51
.
41
.
35
.
3
BR1 clay matrix
0
.
43
.
130
.
8
44
.
00
.
33
.
40
.
20
.
7
0
.
0
17
.
1
BR1bis clay matrix
0
.
22
.
930
.
8
44
.
20
.
43
.
30
.
20
.
7
0
.
0
17
.
2
BR2 clay matrix
0
.
23
.
226
.
3
48
.
8
0
.
33
.
60
.
50
.
90
.
115
.
7
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IANSA 2022 ● XIII/2 ● 155–162
Maria Pia Riccardi, Deneb Cesana, Maya Musa, Sergio Martini, Francesco Zucca: Petro-Archaeometric Study of Pre-Roman Pottery from the Archaeological Site of
Bec Berciassa (Roccavione, Cuneo, North-West Italy): Technological Remarks from Petrographic Study of Tempers
161
The chemical composition of the clay matrix was detected
by EDS on an area of 100 X 100 microns. The data shown in
Table 2 represent the average of 3 measurements. The clay
matrix showed high content of Al
2
O
3
and SiO
2
and consistent
values of Fe
2
O
3
. The CaO content varied from a minimum of
0.2 wt% to a maximum of 18 wt%. The presence of P
2
O
5
in
Middle Iron Age artefacts is ubiquitous (Table 2). However,
the presence of phosphorus, and partially the content of
CaO, are often related to secondary processes occurring in
the archaeological deposit in the post-burial phase (Lemoine
and Picon, 1982; Buxeda i Garrigós, 1999; Maritan and
Mazzoli, 2004; Schwedt
et al.
, 2004; Fabbri and Gualtieri,
2013; Maritan, 2020 and references therein). The clay matrix
is always the same in all the samples, from the Bronze Age
production to the Middle Iron Age production (Figure 5).
3.2 The pebbles of the Vermenagna and Gesso rivers.
The pebbles of the Vermenagna and Gesso riverbeds are mainly
intrusive rocks, such as granites, aplites and granodiorites,
and metamorphic rocks. Among the metamorphic rocks,
schists are the most abundant, calc-schist, mica schists and
sericitic schists. Intrusive and metamorphic rocks account
for 70% of the pebbles. Quartzites, sandstones, tufaceous
sandstones (following the petrographic classifcation by
Schmid, 1981), and volcanic rocks are present in a smaller
percentage. Carbonate rocks, mainly dolomite, are the least
common (Figure 2B).
4. Discussion
The petrographic studies on the coarse ware ceramics
from the Bec Berciassa archeological site, carried out
on thin sections, have allowed many clues to be gathered
for reconstructing the technological steps at the basis of
production. The survey and sampling campaign of the area
surrounding the archaeological site was targeted at potentially
useful materials for ceramic production, any possible leads
to the identifcation of the sources of raw materials, and at
determining whether the pottery was locally produced or
from another cultural context.
Based on the petrographic and modal features, fve types
of mixtures were identifed, all of which were made from
an iron-rich clay matrix with crushed rocks added as fller:
1. Fe-rich clay matrix + intrusive rocks (granite and
aplite) ± calcite/dolomite ± sericitic schists;
2. Fe-rich clay matrix + sericitic schists ± sandstones,
± quartzite ± intrusive rocks;
3. Fe-rich clay matrix + calc-schists ± sericitic schists;
4. Fe-rich clay matrix + quartzite ± intrusive rocks
± sercitic schist;
5. Fe-rich clay matrix with clay pellets.
All the lithologies found in the temper of the pottery are
present in the pebbles collected from the riverbeds of the
Vermenagna and Gesso rivers.
The mixtures show no correlation with shape, function
and decoration.
In the production of the ceramic bodies, there is one aspect
that does not ft with an adjustment to the plasticity of the
mixtures. Looking at the petrography of the fllers, it can
be seen that there are always other types of crushed rocks
associated with the most abundant lithotype. These rocks
are at a low percentage (<5–7% to 10%) and their voluntary
addition does not change the functional characteristics of the
fller. The clay matrix is a Fe-rich clay used continuously
from the Bronze Age to the Middle Iron Age. This continuity
of use, combined with the evidence that its composition
remains the same for all artefacts, supports the hypothesis
that it is a local soil. In fact, a reddish palaeosol outcrops at
the contact between the “grey limestone formation” and the
sericitic schists. This geological deposit could be the source
Figure 5.
Ternary diagram SiO
2
– Fe
2
O
3
–
Al
2
O
3
. The chemical composition of the
clay matrix is the same as that of the clay
pellets. This composition does not change
from Bronze Age ceramics to Middle Iron
Age ceramics.
image/svg+xml
IANSA 2022 ● XIII/2 ● 155–162
Maria Pia Riccardi, Deneb Cesana, Maya Musa, Sergio Martini, Francesco Zucca: Petro-Archaeometric Study of Pre-Roman Pottery from the Archaeological Site of
Bec Berciassa (Roccavione, Cuneo, North-West Italy): Technological Remarks from Petrographic Study of Tempers
162
of supply of the earth used in production. However, the
conducted survey of clay deposits was more complex than
the study of fller supply sources. A survey for the geologic
deposits that could have consistently supplied the clayey raw
material over this long period of time is presently in progress.
It is therefore very probable that the technology of production
of the pottery was very simple and that the mixture was only
one, and this remained constant over a long time. We can
say that the plastic fraction of the mixture is a Fe-rich clay
deposit, and probably local given the continuity of supply.
Moreover, its composition remained constant over historical
time. Furthermore, crushed pebbles that were available in
the riverbeds of the Gesso and Vermenagna rivers were then
added to this clay matrix.
The fller was probably obtained by heating the pebbles
and then their subsequent abrupt cooling. The fller would
thus undergo particle size selection.
5. Conclusion
The production of pottery at the Bec Berciassa archaeological
site was made with local geological materials: a red clay
(Fe-rich clay), to which pebbles from the rivers Vermenagna
and Gesso were added after being appropriately crushed.
One may suppose a production sequence that frst has
a treatment of the pebbles, heating and then a thermal shock
to obtain their crushing, and then maybe also a size selection
to remove the fne fraction. This would explain the hiatal
texture of the artefacts.
A curious aspect noted from our study is that most of the
lithotypes used as fllers always consist of light (white) rocks.
The supply of raw materials used remained constant over
a long period, from the Bronze Age to the Middle Iron Age.
Acknowledgements
This paper is part of the research activities of the project “At
the origins of alpine culture: Bèc Bërchasa, the restoration
and promotion of a protohistoric settlement”, strongly
supported by the Municipality of Roccavione and by the
Compagnia di San Paolo Foundation, CRT Foundation, and
Buzzi Unicem. The authors are grateful to all these public and
private institutions for their support. We would also like to
thank the Mibact – Soprintendenza Archeologica Belle Arti
e Paesaggio per le provincie di Alessandria, Asti e Cuneo
for their fruitful scientifc and organisational exchanges.
The authors thank the reviewers for their suggestions that
improved the completeness of the paper.
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