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21
XI/1/2020
INTERDISCIPLINARIA ARCHAEOLOGICA
NATURAL SCIENCES IN ARCHAEOLOGY
homepage: http://www.iansa.eu
The Benefts of Using Radiocarbon Dating and an Interdisciplinary Approach
for Identifying Contamination of Archaeological Find Assemblages. A Case
Study from the Multi-period Settlement Site at Rakovice, Czech Republic
Tereza Šálková
a,b,c*
, Tomáš Hiltscher
a
, Dagmar Dreslerová
d
, Lenka Kovačiková
c
, Jaroslav Jiřík
a,e
a
Prácheň Museum in Písek, Velké náměstí 114, Písek, Czech Republic
b
Faculty of Arts, Institute of Archaeology, University of South Bohemia in České Budějovice, Branišovská 31a, 370 05 České Budějovice, Czech Republic
c
Faculty of Science, Laboratory of Archaeobotany and Palaeoecology, University of South Bohemia in České Budějovice, Branišovská 1760,
370 05 České Budějovice, Czech Republic
d
Institute of Archaeology of the Czech Academy of Sciences, Prague, Letenská 4, 11801 Praha 1, Czech Republic
e
Faculty of Arts, Institute for Archaeology, Charles University in Prague, Náměstí Jana Palacha 2, 116 38 Prague 1, Czech Republic
1. Introduction
Earlier residuality and later intrusion in archaeological
assemblages are key problems in settlement sites with a long
history of human occupation. The spectra of artefact and
ecofact assemblages in the features are often contaminated – at
least partially – as a result of depositional or post-depositional
processes (Borojevic, 2011; Kuna and Němcová,
et al.
2012;
Pelling
et al.
, 2015; Peeling
et al.
, 2015; Šálková
et al.
,
2016). Our multi-disciplinary analysis of the assemblage of
plant remains from the superposition of two features from
the Early Roman and Early Mediaeval periods from the site
at Rakovice, Czech Republic (Figure 1), demonstrates the
importance of such analysis for recognizing contamination
of the features’ flls. An archaeological feature, severely
damaged by ploughing, was found during a surface survey
in April 2015. The subsequent excavation revealed what
appeared to be a simple stratigraphic scenario. A shallow,
sunken, elongated feature 1 (hereafter referred to as F 1)
was partially disrupted in its north-western part by another
shallow oblong feature 1.1 (hereafter referred to as F 1.1).
Based on pottery fnds, F 1 was dated to the beginning of the
Early Roman period (several sherds also date to the La Tène
period). The stratigraphically later F 1.1 was dated to the
Early Mediaeval period. However, during processing of the
archaeobotanical fnds, the formation of the fll of these two
features began to raise questions. Especially dubious was a
large quantity of charred fax seeds (
Linum usitatissimum)
recovered in similar quantities from both features. AMS
radiocarbon data on the fax and other plant macroremains
subsequently confrmed that the formation of the features’
flls was more complex than it had appeared on the basis
of the feld observations and the typological analysis of the
pottery fragments.
Volume XI ● Issue 1/2020 ● Pages 21–31
*Corresponding author. E-mail: terezasalkova@seznam.cz
ARTICLE INFO
Article history:
Received: 2
nd
April 2020
Accepted: 17
th
June 2020
DOI: http://dx.doi.org/10.24916/iansa.2020.1.2
Key words:
contamination
taphonomy
plant macroremains
Linum usitatissimum
radiocarbon dating
archaeology
ABSTRACT
The contamination of archaeological fnd assemblages at multi-period (and other) sites can sometimes
go undetected. In this article we seek to highlight this problem through analysis of the fll of settlement
features from a site at Rakovice, South Bohemia, Czech Republic. After a detailed spatial evaluation
of diferent categories of fnds, an analysis of plant macroremains, and radiocarbon dating, what had
originally appeared to be a clear-cut archaeological situation of the superposition of two features
from the Roman and Early Mediaeval periods was shown to be much more complex. This discovery
confrmed the value of a multi-disciplinary approach and especially of radiocarbon dating even in
apparently simple contexts. What we are especially concerned about is the risk of assigning particular
periods to multi-period sites that have been insufciently radiocarbon dated.
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Tereza Šálková, Tomáš Hiltscher, Dagmar Dreslerová, Lenka Kovačiková, Jaroslav Jiřík: The Benefts of Using Radiocarbon Dating and an Interdisciplinary Approach
for Identifying Contamination of Archaeological Find Assemblages. A Case Study from the Multi-period Settlement Site at Rakovice, Czech Republic
22
In this article we aim to demonstrate that: (a) the earlier
residuality and later intrusion of plant remains can be
crucial for archaeological interpretation even in a situation
that appears stratigraphically clear and in which each
archaeological feature comprises only artefacts (mostly
ceramics) dated to specifc periods; (b) the true formation
history and “contamination” cannot be recognized without
radiocarbon dating of several specimens and without detailed
knowledge of the local archaeology and the spectrum of
plants cultivated in a particular period. Our objective is to
highlight the dangers of unrecognized contamination and the
subsequent misinterpretation of archaeological contexts, and
to suggest that such contamination can only be revealed by
a multi-disciplinary approach and by including radiocarbon
dating.
2. Materials and methods
2.1 Background information
The site under investigation is situated in the north-western
part of the Písek region (South Bohemia, Figure 1), which
was settled in the Upper Palaeolithic and Mesolithic, the Iron
Age, the Early Roman period, and from the early Middle
Ages until the present (Břicháček and Fröhlich, 1993;
Dubský, 1925; Debnar, 2000; Dreslerová, 2004; Fröhlich
et al.
, 2008; Hiltscher
et al.
, 2018).
The soil horizon consists mainly of gleyic modal
stagnosols generated on the polygenetic loam substrate
and glacial sediments (Němeček and Lérová, 2009). The
site is at 465 m asl. in the warmest part of South Bohemia,
which is also, except for the region of the upper Vltava and
Elbe lowlands, the warmest part of the whole of Bohemia
(Quitt, 1971).
Luzulo albidae-Quercetum petraeae
and/or
Abieti-Quercetum
were reconstructed as the potential natural
vegetation (Neuhäuslová
et al.
, 1997).
2.2 Archaeological excavation
An excavation trench covering an area of 20 m
2
was dug
in the area with the highest accumulation of ploughed-
out pottery and divided into a network of 1 m squares
(Figure 2). The flls of the sunken features were excavated
in 10-cm-thick mechanical layers. F 1 (with a volume
of approx. 17,000 l) was a fat, irregular, elongated pit,
oriented north-south. The bottom was slightly concave.
There was a concentration of stones at the southern end,
under which a larger quantity of pottery fragments were
excavated. The fll was dark brown: a black loamy deposit
with a high content of a charcoal admixture. It contained
fragments of pottery, animal bones, and a spindle whorl.
F 1.1 (with a volume of approx. 6,700 l) was a shallow,
oblong pit, oriented northeast-southwest, with a fat bottom
and cutting into F 1. The fll was dark brown: again, a black
loamy deposit with a high content of a charcoal admixture.
F 1.1 contained fragments of pottery, animal bones, and a
glass bead.
A sample of sediment with a volume of 10–25 litres
from each square and layer was processed by fotation in a
fotation tank (modifed ANAKARA type) using a 0.25 mm
square mesh sieve for the foating of the organic component
and a 0.5 mm sieve for the mineral component (Pearsall,
1989). Some 38 samples with a total volume of 516 litres
were processed (325 litres from F 1; 105 litres from F 1.1;
86 litres from the boundary area between the two features).
Archaeobotanical and archaeozoological material and fne
artefacts from the fotation and heavy residue fractions were
sorted and analysed further (for details, see Excavation
report no. C-201901695; AMČR).
2.3 Analysis of plant macroremains
The samples were studied under a stereomicroscope. All
botanical material was sorted, but only the charred plant
macroremains were taxonomically determined and counted
Figure 1.
Position of the Rakovice site
(marked by a dot) within the Czech Republic.
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Tereza Šálková, Tomáš Hiltscher, Dagmar Dreslerová, Lenka Kovačiková, Jaroslav Jiřík: The Benefts of Using Radiocarbon Dating and an Interdisciplinary Approach
for Identifying Contamination of Archaeological Find Assemblages. A Case Study from the Multi-period Settlement Site at Rakovice, Czech Republic
23
because in dry environments it is likely that non-charred
plant remains are a modern intrusion. Seeds and fruits were
classifed according to reference collections and the literature
(Anderberg, 1994; Berggren, 1981; Cappers
et al.
, 2006;
Hajnalová, 1993; Hajnalová, 1999; Lhotská and Chrtková,
1978; Jacomet, 2006).
Figure 2.
Concentration of plant macroremains in one litre of the fll in particular sectors: A (blue dots): density of fax seeds; B (green dots): density of
macroremains without fax.
0 200 cm
0 200 cm
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Tereza Šálková, Tomáš Hiltscher, Dagmar Dreslerová, Lenka Kovačiková, Jaroslav Jiřík: The Benefts of Using Radiocarbon Dating and an Interdisciplinary Approach
for Identifying Contamination of Archaeological Find Assemblages. A Case Study from the Multi-period Settlement Site at Rakovice, Czech Republic
24
Archaeological assemblages of crops from South Bohemia
dated to the Early Roman period (Přešťovice, Rataje, Dolní
Bukovsko; Šálková
et al.
, 2014) and the Early Mediaeval
period (Netolice, Nemětice, Počáply, Svákov u Soběslavi,
Slavonice, Staré Prachatice; Chvojka
et al.
, 2012; Parkman
et al.
, 2015; Beneš
et al.
, 2014; Opravil, 2000) were used as
reference samples.
2.3.1 Multivariate statistics of archaeobotanical data
To detect and understand the patterning of the data from the
site and in the regional context, archaeobotanical data were
studied using multivariate statistical analysis performed in
the Canoco v. 5 programme (ter Braak and Šmilauer, 2002).
Detrended correspondence analysis (DCA) was carried out
for data from the site. The maximum length of the gradient
was 3.0. Logarithmic transformation of the data was
used. The DCA was used to compare the regional context
archaeobotanical data as the gradient length was 3.19.
Percentages and logarithmic transformation were used to
evaluate the regional data.
2.4 Osteological analysis
Archaeozoological material was obtained by both hand-retrieval
and fotation. The analysis of this material serves as a referential
method for the study of depositional and post-depositional
processes. Bone concentration was the same in both features.
Taxonomically determined animal bones and teeth were
quantifed as NISP (Number of Identifed Specimen).
The age of cattle was estimated according to the phase of
eruption, replacement (Higham, 1967) and the wear stage of
teeth (Legge, 1992). When identifying the slaughter age of
domestic pigs, the tooth replacement and the stage of crown
wear was observed (Grant, 1982). The age of sheep and goat
was determined on the basis of abrasion indexes for molars
(Helmer and Vigne, 2004).
2.5 Radiocarbon dating
To secure the representative taxa for archaeologically-
detected periods, radiocarbon dating of ten samples of
charred fax seeds, and the caryopses of common wheat
(
Triticum aestivum
)
,
einkorn (
Triticum monococcum
), barley
(
Hordeum vulgare
) and corn-cockle (
Agrostemma githago
)
were performed in two sets of AMS measurements: the frst
in the laboratory of the University of Georgia (UGAMS);
the second set of graphites was prepared in the Czech
Radiocarbon Laboratory (CRL) (Table 1, Figure 3) and the
measurements were taken at the MICADAS facility in the
Hertelendi Laboratory of Environmental Studies (DebA),
ATOMKI HAS, in Debrecen, Hungary. Calibrations were
performed in OxCal, version 4.3. (Reimer
et al.
, 2013).
Animal bones from the site did not contain a sufcient
amount of collagen to enable dating.
3. Results
3.1 Artefacts
A total of 797 fragments of pottery and 35 daub fragments
were collected from the topsoil and excavation trench. Some
566 fragments of pottery from F 1 were dated to the beginning
of the Early Roman period (35 BC–180/200 AD) (Droberjar,
2008), and one fragment to the La Tène period (400–25 BC).
From F 1.1, 64 fragments were dated to the Early Mediaeval
period, specifcally to the so-called Middle Hillfort period
(800/850–950 AD) (Parkman, 2003; Lutovský, 2011). No
artefacts from other periods were found in the features.
3.2 Plant macroremains
We obtained 2,617 fnds of charred macroremains (1,225 from
F 1; 698 from F 1.1; 694 from the boundary area between the
two features). Taxa composition varied in the two features. The
trends are similar (Figure 4a, 4b) but the average density of
plant macroremains in one litre of deposit difer considerably,
with 2.5 PR/l (plant remains per litre) in F 1 and 12.6 PR/l in
F 1.1 (for more detail, see Figure 2). Cereal remains dominate
in both features (F1 – 38%; F 1.1 55%). The remains of weeds
and ruderals are subdominant (F 1 34%; F 1.1 23%). The
remains of oil crops,
e.g.
fax seeds, were numerous (F1 19%;
Table 1.
AMS radiocarbon dates. Data were calibrated by OxCal v4.2.4 (Bronk Ramsey, 2013) and IntCal13 (Reimer
et al.
, 2013).
CodeSampleFeatureSectorMechanical
lyer
TaxaPredicted dating
based on artifacts
Bp±Calibrated date
(95,4%)
UGAMS23270401
1
I10–bottom
Linum usitatissimum
Roman period112020887 – 981 AD
UGAMS2327140601.IL0–10cm
Linum usitatissimum
Early Middle ages107025897 – 1020 AD
17_510415
1
R20–bottom
Triticum aestivum
Roman period
1221
20712 – 885 AD
17_51142401.IF10–bottom
Agrostemma githago
Early Middle ages120523727 – 888 AD
19_103 407
1
I0–10
Linum usitatissimum
Roman period
112121
886 – 983 AD
19_104 41001.IL0–10
Linum usitatissimum
Early Middle ages1116
22
888 – 984 AD
19_105 434
1
R10–20cm
Triticum monoccocum
Roman period203223108 BC – 28 AD
19_106 41401.IG0–10
Linum usitatissimum
Early Middle ages1113
21
890 – 984 AD
19_107 428
1S
0–bottom
Linum usitatissimum
Roman period1078
21
898 – 1017 AD
18_07141001.IL0–10
Hordeum vulgare
Early Middle ages118620773 – 889 AD
––01.IF0–10
Bos taurus
Early Middle ages–––
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for Identifying Contamination of Archaeological Find Assemblages. A Case Study from the Multi-period Settlement Site at Rakovice, Czech Republic
25
F 1.1 11%); legumes were rather scarce in both features. Seeds
and fruits of species found in woodland and at woodland
edges which might have been collected and used for various
purposes are also scarce but regularly occur in many samples
(F1 4%; F 1.1 6%). Plants typical of wet meadows were found
in similar quantities (4% in both features; Figure 4a). Common
millet (
Panicum miliaceum
) was the dominant cereal crop in
both assemblages. Barley (
Hordeum vulgare)
and common
wheat
(Triticum
aestiv
um)
were subdominants.
Cereals belonging to a group of staples typical of
earlier prehistoric agriculture, such as einkorn (
Triticum
monococcum;
F 1.1), emmer (
Triticum dicoccum;
F 1) and
spelt (
Triticum spelta;
F 1 and F 1.1), were found in the
assemblages in small quantities.
Both assemblages also contained small quantities of
“progressive” cereals such as oats (
Avena
cf.
sativa
) and rye
(
Secale sereale
) (Figure 4b).
Only a few legume seeds were found: lentil (
Lens
culinaris
) in F 1 and lentil and peas (
Pisum sativum
) in F 1.1.
Large numbers of seeds (and a small number of capsules)
of common fax (
Linum usitatissimum
) were found in both
features (Figure 2a).
Both features contained macroremains of potentially
useful plants which probably originated in woodland or at
Figure 3.
Group diagram comparing the
dating of samples. Green: interval of the ERP
pottery typological dating; red: interval of
the EMP (so-called Middle Hillfort period)
pottery typological dating. Calibration
according to Reimer
et al.
(2013).
Figure 4.
A – Reconstruction of spectra of plants from diferent ecological groups in F 1 and F 1.1 (logarithmic scale); B – Spectra of cereal remains in F
1 and F 1.1 (logarithmic scale).
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Tereza Šálková, Tomáš Hiltscher, Dagmar Dreslerová, Lenka Kovačiková, Jaroslav Jiřík: The Benefts of Using Radiocarbon Dating and an Interdisciplinary Approach
for Identifying Contamination of Archaeological Find Assemblages. A Case Study from the Multi-period Settlement Site at Rakovice, Czech Republic
26
woodland edges, such as
Rubus ideaus
,
Rubus fruticosus
,
Corylus avellana
,
Fragaria/Potentilla. Luzula luzuloides
seeds in F 1 also suggest a woodland environment. An
achene of
Fragaria vesca,
and a fragment of a
Prunus
sp.
stone were found in F 1, and stones of
Prunus domestica
subsp.
insititia
in F
1.1. Both features contained fnds of
achenes of
Sambucus nigra,
and in F 1 also those of
S. ebulus
and S. racemosa
.
Both features yielded a wide spectrum of plant remains
typical of felds and scrubland.
Galium spurium
and
Chenopodium album
were the most abundant.
Vicia
tetrasperma
,
Galium aparine
,
Agrostemma githago
,
Setaria
sp.,
Polygonum aviculare
and
Fallopia convolvulus
were
often found in large quantities in both features. A wide range
of taxa were found in both features, but from each taxa only
a few macroremains, namely:
Vicia
sp.,
Atriplex
sp.,
Silene
alba
,
Centaurea
cf.
cyanus
,
Chenopodium fcifolium
, and
Viola
sp.
Veronica hederifolia
,
Chenopodium hybridum
,
Medicago lupulina
,
Scleranthus annuus
and
Setaria pumila
appeared only in F 1, as did
Bromus
sp.,
Fumaria ofcinalis
,
and
Polycnemum arvense
.
Plant remains typical of wet meadows included
Phleum
pratense
,
Alopecurus pratense
and
Juncus
sp. Small
quantities of Carex sp.,
Trifolium
,
Trifolium/Medicago
,
Trifolium pratense
,
Persicaria lapathifolia
and
Plantago
lanceolata
were found in both features
. Lychnis fos-cuculi
was found only in F 1.1;
Myosotis
sp.,
Ranunculus fammula
and the aquatic plant
Potamogeton
only in F 1
.
On the other
hand,
Acinos arvensis,
whose seeds were found in small
numbers in both features, is typical of drier habitats.
The collections are similar regarding both the species and
the reconstruction of the original plant biotopes (Figure 4 b).
However, multivariate statistical analysis showed that the
samples from the two features difer in their composition of
characteristic botanical taxa (Figure 5).
3.2.1 Reference assemblages
The Early Mediaeval period (hereafter referred to as the
EMP) reference assemblage from South Bohemia comprises
6,984 remains of cultural plants from six sites; the Early
Roman period (hereafter referred to as the ERP) assemblage
comprises 229 remains of crops from three sites.
The same taxa are present in both periods but in diferent
proportions (Figure 6). The main diference is in the presence
or quantity of glume wheats such as emmer, spelt and
einkorn. While in the ERP samples these usually comprise
over 20%, in EMP samples, if present at all, they rarely reach
1% (and these may be undetected residuals/contaminants).
The ERP samples are usually dominated by free-threshing
wheat or barley; in the EMP there is either free-threshing
wheat or wheat in combination with millet. Rye and oat are
more numerous in the EMP than in the ERP. The samples
from both periods from Rakovice (RF 1 and RF 1.1) not only
difer from the reference collections but are strongly similar
to each other with respect to the dominant combination of
millet and barley (and free-threshing wheat). They difer in
the amount of glume wheats, but the ERP did not reach the
expected rate of 20%.
Detrended correspondence analysis (DCA) supports the
results of the simple statistics (Figure 6) for the evaluation of
the site in the context of the referential assemblages. It shows
that the taxonomic composition and ubiquities of individual
taxa in the Rakovice samples difer from those of EMP and
ERP assemblages (Figure 5), but also that the composition of
the taxa from the two features at Rakovice is almost identical
(Figure 8). The major diference from other samples is the
high proportion of millet and barley in both features.
3.3 Osteological analysis
Osteological material consisted of 880 fnds whose average
concentration was similar in F 1 and F 1.1, with 0.03 bones
per litre of deposit. Some 432 animal bones were burnt at
high temperatures.
F 1 contained 496 osteological fnds but only 45 were
taxonomically determined. Most of the fnds from F 1,
73.3% NISP, belonged to Suinae (
Sus
sp.); a smaller number,
22.2% NISP, were Bovinae (
Bos
sp.). Although the wild and
domesticated animals is not easily distinguished, we suppose
Figure 5.
Detrended correspondence
analysis (DCA). Green: samples from
F 1; blue: samples from F 1.1; yellow:
samples from boundary area between the
two features. First axis explains 17.78%
variability; the frst and the second axis
together 24.24%.
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Tereza Šálková, Tomáš Hiltscher, Dagmar Dreslerová, Lenka Kovačiková, Jaroslav Jiřík: The Benefts of Using Radiocarbon Dating and an Interdisciplinary Approach
for Identifying Contamination of Archaeological Find Assemblages. A Case Study from the Multi-period Settlement Site at Rakovice, Czech Republic
27
that the 3
rd
upper molar of pig belonged to a domesticated
specimen slaughtered at the age between 16 and 20 months.
Cattle (
Bos taurus
) is documented by a fragment of a
metatarsal bone and three molars, one of which belonged to a
young individual and the second to a 7- or 8-year-old animal.
One molar documents the occurrence of a subadult sheep or
goat (
Ovis/Capra
). Among the fnds of smaller mammals are
the bone remains of a vole (
Microtus
sp.). The assemblage
also contained two eggshell fragments of bird.
F 1.1 contained 173 bones and teeth, of which only 5.2%
were identifed, including cattle, sheep or goat aged 4–6 years,
and a vole. There were also bird bones (at the size of a chicken).
From the boundary area between the two features,
221 fragments of bones and teeth were recovered, of which
Figure 6.
Reference assemblages of crop
remains from the Early Roman and Early
Mediaeval periods of South Bohemia.
Left: EMP. RF1.1 = Rakovice F 1.1; SSL =
Soběslav-Svákov; POC = Počáply; HUN =
Hradec u Nemějic; SPR = Staré Prachatice;
NET = Netolice; SLA = Slavonice.
Right: ERP. RF1 = Rakovice F 1; DBO =
Dolní Bukovsko; RAT = Rataje; PRE =
Přešťovice. TA =
Triticum aestivum
; TAC
=
Triticum compactum
; PM =
Panicum
miliaceum
; HV =
Hordeum vulgare
; SC =
Secale cereale
; AV =
Avena sativa
; TD =
Triticum dicoccum
; TS =
Triticum spelta
;
TM =
Triticum monococcum
.
Figure 7.
Contexts of the radiocarbon-
dated samples. Blue dots: 0–10 cm; red
dots: 10 cm–bottom. AMS date assigned
to: yellow centre: Late La Tène, early RP;
brown centre: Middle Hillfort period; green
centre: later phase of Middle Hillfort period
to earlier phase of Late Hillfort period (all
fax seeds).
0 200 cm
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Tereza Šálková, Tomáš Hiltscher, Dagmar Dreslerová, Lenka Kovačiková, Jaroslav Jiřík: The Benefts of Using Radiocarbon Dating and an Interdisciplinary Approach
for Identifying Contamination of Archaeological Find Assemblages. A Case Study from the Multi-period Settlement Site at Rakovice, Czech Republic
28
admixture from the (late) La Tène period; the later F 1.1
comprised pottery classifed clearly into the EMP.
The archaeozoological analysis showed diferences in
the spectrum of taxa in both features, but the number of
determined fnds was too low to draw wider archaeological
conclusions.
The plant macroremains difered slightly in taxa and
density, but it seems that at present the spectrum of crops from
the ERP and EMP in South Bohemia is not chronologically
sensitive enough (Figure 8). To assign two assemblages
of plant macroremains to archaeological periods simply
on the basis of their plant spectra and taxa ratio is highly
problematic.
Radiocarbon dating showed that the plant macroremains
in F 1 originated from at least three diferent periods: the
Late La Tène period or ERP; the earlier part of the EMP
(Early to Middle Hillfort period); and the later part of the
EMP (Middle to Late Hillfort period). This is partly in
agreement with the relative dating of the artefacts. The plant
remains in F 1.1 originated in the two periods or phases of
the EMP. It is also clear that the intervals of the earlier and
later EMP data do not overlap and therefore represent two
diferent phases of occupation of the site.
The chronology of the artefacts of the Late La Tène and
ERP at Rakovice is more sensitive than the interval of the
absolute data obtained by the radiocarbon analysis. It is not
possible, therefore, to assign this radiocarbon date to either
of these periods. In the case of the EMP, the result is the
opposite. The sensitivity of the typological chronology
of pottery from this period is low (Lutovský, 1998). It is
not possible, therefore, to say whether the artefacts come
from the earlier or later EMP phase or indeed from both
(Figure 9). The frst possibility can be supported by the
occurrence of two archaic-looking fragments of the upper
parts of vessels. A decoration of random, narrow, vertical
cuts was also registered on a pot discovered at a nearby
burial mound at Kožlí near Orlík nad Vltavou, which was
radiocarbon dated to 632–764 cal AD (Lutovský, 1996,
47). Finds of such an age were previously unknown in the
Rakovice microregion.
4.2 Formation of the flls of F 1 and F 1.1
The presence of relatively high concentrations of common
fax seeds in both features is crucial for the interpretation of
the formation of their fll. In previous studies, fax has not
been documented in the RP in South Bohemia and all dated
fax seeds selected from both features and from the boundary
area between them are from the later EMP. Flax seeds
contain a large amount of oil and during carbonization often
burn without leaving macroscopic evidence (
e.g.
Kočár and
Dreslerová, 2010). Carbonized seeds are fragile and prone
to breaking or being totally destroyed. As the preservation
of the Rakovice fax seed is good, the carbonization must
have happened at low temperatures and in the partial
absence of air (Märkle and Rösch, 2008). Furthermore, pre-
and post-depositional processes caused little destruction
to the seeds, which could suggest that the period between
Figure 8.
Detrended correspondence analysis (DCA). Blue dots: early RP;
red star: EMP. First axis explains 30.53% variability; the frst and the second
axis together 49.46%.
7.6% were identifed. The bones of cattle
,
pig, and mouse-
or vole-like rodents (probably a common vole,
Microtus
arvalis
) were determined. A recent origin for the rodents
cannot be excluded. The vertebra of a lizard (Lacertidae) and
a small fsh were also present.
3.4 Radiocarbon dating
The common fax seeds from both features were dated
between 1070 and 1121 ± 20–25 BP. The corn cockle from
F 1.1 was dated to 1205 ± 23 BP; the naked wheat caryopsis
from F 1 to 1221 ± 20 BP; the barley caryopsis from F 1.1 to
1186 ± 20 BP (Table 1, Figures 3, 7). Calibrated data show
three dating intervals. The caryopsis of einkorn found in F 1
was dated to 1032 ± 23 BP. It corresponds to the ERP pottery
and to an older residuum of the fnal phase of the La Tène
period. Macroremains falling into the earlier EMP and fax
seeds from the later part of the EMP horizon were present in
both features.
4. Discussion and interpretation
4.1 Dating alternatives
Our research detected part of a settlement area that was
repeatedly used in late prehistory and the EMP. Long-term
exploitation of the area meant the fll of the two features
comprised earlier residuals and later intrusions.
With respect to artefact analysis, the dating of the features
was straightforward. The stratigraphically earlier F 1
comprised fnds from the ERP, with an insignifcant pottery
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Tereza Šálková, Tomáš Hiltscher, Dagmar Dreslerová, Lenka Kovačiková, Jaroslav Jiřík: The Benefts of Using Radiocarbon Dating and an Interdisciplinary Approach
for Identifying Contamination of Archaeological Find Assemblages. A Case Study from the Multi-period Settlement Site at Rakovice, Czech Republic
29
their carbonization and deposition was relatively short and
probably refects a single event. Flax seeds were distributed
throughout the fll of the two features, but their concentration
in F 1.1 was signifcantly higher than in F 1 (Figure 2).
Bioturbation as a source of contamination of the two features
by fax seeds can be ruled out because of the absence of a
higher concentration of seeds in the overlying horizons of F 1
and F 1.1, and because of the highly regular distribution of
Figure 9.
Examples of pottery fragments from F 1.1. (EMP) and F 1 (ERP).
0 5 cm
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Tereza Šálková, Tomáš Hiltscher, Dagmar Dreslerová, Lenka Kovačiková, Jaroslav Jiřík: The Benefts of Using Radiocarbon Dating and an Interdisciplinary Approach
for Identifying Contamination of Archaeological Find Assemblages. A Case Study from the Multi-period Settlement Site at Rakovice, Czech Republic
30
the seeds throughout the fll: contamination by bioturbation
usually results in concentrations of remains in small areas
represented by, for example, animal burrows or tunnels.
The most likely scenario is that both features and their flls
formed in the later EMP. This means the fll of F 1 represents
a sediment comprising pottery and archaeobotanical fnds
redeposited in the pit from an unknown Roman period
feature or features, or a settlement layer situated somewhere
within the multi-period settlement which was enriched by
earlier EMP deposits or waste used to fll up the later EMP
feature. Sometime either before or during the deposition of
the fll, the organic material containing charred fax seeds
was admixed. In this scenario, F 1.1 would represent not
a separate sunken feature but a stratigraphic unit of F 1.
Alternatively, F 1.1 could have been dug out and flled
shortly after the flling of F 1. The three dated plant
macroremains (barley, naked wheat, corn cockle) found in
both flls could represent residue from a former feld or other
harvested area, or another unknown feature or settlement
layer from the earlier EMP phase.
The third possible solution suggests that F 1 originated
in the Roman period and F 1.1. in the earlier phase of the
EMP. Activity connected with the processing of fax would
take place here in the later phase of the EMP. Carbonized
waste from this production would then enter the flls of both
features by some unknown and undetermined process (such
as the digging and slight mixing of sediments).
4.3 Identifying the contamination of archaeological
contexts
Based on our fndings we propose that when dealing with
the taphonomy of any archaeological situation, complex or
otherwise, the following steps should be taken:
(i) Remove all material systematically according to a
predetermined sampling method, such as using a regular
sampling grid within each mechanical layer of a particular
thickness, or within the context. More than one type of
analysis should be carried out and the results compared. The
quantity of fnds in particular contexts should be transferred
into the same units so the contexts can be compared directly
(
e.g.
density of fnds as an average number of fnds per one
litre of sediment/deposit). The results should be interpreted
in the context of the overall research.
(ii) Compare the results from each type of analysis with
the (well-known) regional data.
(iii) Perform radiocarbon dating of organic fnds even if
the contexts seem to be clearly dated on the basis of typology,
stratigraphy, or other types of dating.
(iv) Carry out a multidimensional analysis of the data.
5. Conclusion
A detailed archaeo-environmental analysis of a seemingly-
simple fnd situation revealed the hidden danger of
unrecognized depositional processes. We have shown that it
can be misleading to “transfer” dating based on the typology
of artefacts directly to other types of materials in the same
context. Each category of material should be studied on its
own.
Detailed and systematic sampling and fotation of
the archaeological deposits that formed the fll of both
features uncovered evidence that proved crucial for the
archaeological interpretation. The flls do not represent
closed fnd assemblages representing a single event, and
their formation was strongly infuenced by depositional or
pre- or post-depositional processes. Radiocarbon data show
that the plant macroremains are from more time periods than
was documented by artefact typology.
The plant macroremains from F 1.1 could be (with
reservation) assigned to a wider time interval of the EMP.
The plant macroremains recovered from F 1 are not
suitable for reconstruction of the palaeoeconomy and the
environment of the ERP (unless all species are dated and
assigned to that period). To avoid introducing a bias, they
should be excluded from studies when regional analysis and
reference material of the period is required. It is also possible
that our reference assemblages are afected by a similar error
(especially the presence of glume wheats in the EMA), as
would have happened in the Rakovice assemblages without
careful analysis and radiocarbon dating.
There is no doubt that human activity took place at the
site in question across four diferent periods: The La Tène
and Roman periods, and the earlier and later phase of the
Early Mediaeval period. One of the occupation phases of the
EMA was recorded only in organic remains and from their
radiocarbon dating. The exact nature of the human activity
remains unclear.
Acknowledgements
This work was supported by the by OP RDE, MEYS,
under the project “Ultra-trace isotope research in social and
environmental studies using accelerator mass spectrometry”,
“Reg. No.
CZ.02.1.01/0.0/0.0/16_019/0000728”.
References
ANDERBERG, A., 1994.
Atlas of Seeds and Small Fruits of Northwest-
European Plant Species with Morphological Descriptions. Part 4
Resedaceae – Umbeliferae
. Stockholm: Swedish Museum of Natural
History.
BERGGREN, G., 1981.
Atlas of Seeds and Small Fruits of Northwest-
European Plant Species with Morphological Descriptions. Part 3
Salicaceae – Cruciferae
. Stockholm: Swedish Museum of Natural
History.
BRONK RAMSEY, C., 2013.
OxCal 4.2.1.
http://c14.arch.ox.ac.uk/oxcal/
OxCal.html.
BŘICHÁČEK, P., FRÖHLICH, J., 1993. Sídliště z doby římské v Probulově
(okr. Písek).
Archeologické výzkumy v jižních Čechách
, 8, 67–74.
BOROJEVIC, K., 2011. Interpreting, dating, and re-evaluating the botanical
assemblage from tell Kedesh: A case study of historical contamination.
Journal of Archaeological Science
, 38, 829–842.
CAPPERS, R., BEKKER, R., JANS, J., 2006.
Digitale Zadenatlas van
Nederland
[Digital seed atlas of The Netherlands]
.
Groningen: Barkhuis
image/svg+xml
IANSA 2020 ● XI/1 ● 21–31
Tereza Šálková, Tomáš Hiltscher, Dagmar Dreslerová, Lenka Kovačiková, Jaroslav Jiřík: The Benefts of Using Radiocarbon Dating and an Interdisciplinary Approach
for Identifying Contamination of Archaeological Find Assemblages. A Case Study from the Multi-period Settlement Site at Rakovice, Czech Republic
31
Publishing and Groningen University Library.
DEBNAR, A., 2000. Rakovice okr. Písek.
Výzkumy v Čechách
, 1998, 185.
DRESLEROVÁ, D., 2004. Povrchové sběry na severním Prácheňsku
v letech 2001–2003.
Výzkumy v Čechách
,
2002, 369–416.
DROBERJAR, E., 2008. K chronologii nejstarších labskogermánských
(svébských) sídlišť v Čechách. In: E. Droberjar, B. Komoróczy,
D. Vachůtová, eds.
Barbarská sídliště, chronologické, ekonomické
a historické aspekty jejich vývoje ve světle nových archeologických
výzkumů
. Brno, pp. 99–110.
DUBSKÝ, B., 1925. Laténsko-římské sídliště u Zalužan na Mirovicku.
Památky archeologické
, 34, 445–446.
FRÖHLICH, J., JIŘÍK, J., LUTOVSKÝ, M., 2008. Raně středověké
osídlení podél středního toku Vltavy.
Archeologické výzkumy v jižních
Čechách
, 21, 219–246.
GRANT, A., 1982. The use of tooth wear as a guide to the age of domestic
ungulates. In: B. Wilson, C. Grigson, S. Payne, eds.
Ageing and Sexing
Animal Bones from Archaeological Sites
.
British Archaeological Reports,
British Series
, 109, pp. 91–108.
HAJNALOVÁ, E., 1993.
Obilie v archeobotanických nálezoch na
Slovensku.
Nitra: Archeologický ústav Slovenskej akadémie vied.
HAJNALOVÁ, E., 1999.
Archeobotanika pestovaných rastlín
. Nitra:
Slovenská poľnohospodárska universita v Nitre.
HELMER, D., VIGNE, J., 2004. La gestion des cheptels de caprinés
au Néolithique dans le midi de la France. In: P. Bodu, C. Konstantin,
eds.
Approches fonctionnelles en Préhistoire. Actes XXVe Congrès
Préhistorique de France Nanterre, 24–26 novembre 2000. Société
Préhistorique Française Édition
. Paris, pp. 397–407.
HIGHAM, C., 1967. Stock rearing as a cultural factor in prehistoric Europe.
Proceedings of the Prehistoric Society
, 33, 84–106.
HILTSCHER, T., MAŠKOVÁ, H., JIŘÍK, J., 2018. Nové poznatky
k raně středověkému osídlení v povodí toku Skalice – povrchové sběry
A. Debnara.
Prácheňské muzeum v Písku v roce 2017
, 36–90.
CHVOJKA, O., LUTOVSKÝ, M., JOHN, J., MENŠÍK, P., ŠÁLKOVÁ,
T., THOMOVÁ, Z., 2012. Hradiště Svákov u Soběslavi.
Archeologické
výzkumy v jižních Čechách
, 25, 133–164.
JACOMET, S., 2006.
Identifcation of Cereal Remains from Archaeological
Sites,
2nd ed. Basel: IPNA Universität Basel.
KOČÁR, P., DRESLEROVÁ, D., 2010. Archeobotanické nálezy
pěstovaných rostlin v pravěku České republiky [Archaeobotanical fnds
of cultivated plants in the prehistory of the Czech Republic].
Památky
archeologické
, 101, 203–242.
KUNA, M., NĚMCOVÁ, A.,
et al.
, 2012.
Výpověď sídlištního odpadu
[The
evidence of settlement waste]. Praha: Archeologický ústav AV ČR, Praha.
LEGGE, A., 1992.
Excavations at Grimes Graves, Norfolk 1972–1976.
Fascicule 4: Animals, Environment and the Bronze Age Economy
.
London: British Museum Press.
LHOTSKÁ, M., CHRTKOVÁ, A., 1978.
Karpologie a diasporologie
československých zástupců čeledi Fabaceae.
Praha: Academia.
LUTOVSKÝ, M., 1998. Mohylové pohřebiště v Kožlí u Orlíka, okr. Písek.
K poznání raně středověkých mohyl ve středním Povltaví.
Archeologie ve
středních Čechách
, 2, 277–327.
LUTOVSKÝ, M., 2011.
Jižní Čechy v raném středověku. Slovanské osídlení
mezi Práchní a Chýnovem
. České Budějovice: Veduta.
MÄRKLE, T., RÖSCH, M., 2008. Experiments on the efects of
carbonization on some cultivated plant seeds.
Veget Hist Archaeobot
, 17,
257–263. https://doi.org/10.1007/s00334-008-0165-7
MĚŘÍNSKÝ, Z., 2009.
České země od příchodu Slovanů po Velkou
Moravu I.,
Praha: Libri.
NĚMEČEK, J., LÉROVÁ, Z., 2009.
Klasifkace půdních typů podle TKSP
a WRB
, Praha. http://geoportal.gov.cz.
NEUHÄUSLOVÁ, Z., MORAVEC, J., CHYTRÝ, M., SÁDLO, J.,
RYBNÍČEK, K., KOLBEK, J., JIRÁSEK, J., 1997.
Mapa potenciální
přirozené vegetace České republiky 1: 500 000
. Průhonice: Botanický
ústav AV ČR.
OPRAVIL, E., 2000. Archeobotanické nálezy z Hradce u Němětic.
In: J. Michálek, M. Lutovský
,
eds.
Hradec u Němětic: Sídlo halštatské
a raně středověké nobility v česko-bavorském kontaktním prostoru.
Strakonice, Praha, pp. 267–270.
PARKMAN, M., 2003. Osídlení Prachaticka v raném středověku.
Archeologické výzkumy v jižních Čechách
, 16, 129–194.
PARKMAN, M., ŠÁLKOVÁ, T., BENEŠ, J., 2015. Raně středověký
sídlištní objekt ze Starých Prachatic. Příspěvek k paleoekonomii
a absolutnímu datování osídlení.
Archeologické výzkumy v jižních
Čechách
, 28, 187–200.
PEARSALL, S., 1989.
Palaeoethnobotany: A Handbook of Procedures
.
San Diego: Academic Press.
PELLING, R., CAMPBELL, G., CARRUTHERS, W., HUNTE, K.,
MARSHALL, P., 2015. Exploring contamination (intrusion and
residuality) in the archaeobotanical record: Case studies from central and
southern England.
Vegetation History and Archaeobotany
, 24, 85–99.
QUITT, E., 1971.
Klimatické oblasti Československa
. Brno: Geografcký
ústav ČSAV.
REIMER, P., BARD, E., BAYLISS, A., BECK, J., BLACKWELL, P.,
BRONK RAMSEY, C., BUCK, C., CHENG, H., EDWARDS, R.,
FRIEDRICH, M., GROOTES, P., GUILDERSON, T., HAJDAS, I.,
HATTE, C., HEATON, T., HOFFMANN, M., HOGG, A., HUGHEN, K.,
KAISER, K., KROMER, B., MANNING, S., NIU, M., REIMER, R.,
RICHARDS, D., SCOTT, E., SOUTHON, J., STAFF, R., TURNEY, C.,
VAN DER PLICHT, J., 2013. INTCAL13 and MARINE13 radiocarbon
age calibration curves, 0–50,000 years cal. BP.
Radiocarbon
,
55, 1869–
1887. https://doi.org/10.2458/azu_js_rc.55.16947.
ŠÁLKOVÁ, T., DOHNALOVÁ, A., NOVÁK, J., HILTSCHER, T.,
JIŘÍK, J., VÁVRA, J., 2016. Unrecognized taphonomy as a problem
of identifcation and the scale of contamination of archaeobotanical
assemblages – the example of Prague – Zličín Migration period
burial ground.
Interdisciplinaria Archaeologica
–
Natural Sciences in
Archaeology
, 7(1), 87–110. https://doi.org/10.1007/s00334-014-0493-8.
ŠÁLKOVÁ, T., CHVOJKA, O., ZAVŘEL, P., 2014. Archäobotanische
Untersuchungen in vorgeschichtlichen Siedlungen Südböhmens.
FINES
TRANSIRE
, 23, 57–74.
TER BRAAK, C., SMILAUER, P., 2002.
CANOCO Reference Manual
and CanoDraw for Windows User’s Guide: Software for Canonical
Community Ordination (version 4.5).
Wageningen: Biometris.
image/svg+xml