North-East Bulgaria

Geoarchaeology and Archaeomineralogy (Eds. R. I. Kostov, B. Gaydarska, M. Gurova). 2008.
Proceedings of the International Conference, 29-30 October 2008, Sofia, Publishing House “St. Ivan Rilski”, Sofia, 367-373.
GEOARCHAEOLOGICAL STUDIES IN THE SBORYANOVO NATIONAL RESERVE
(NORTH-EAST BULGARIA)
Diana Gergova
National Archaeological Institute with Museum, Bulgarian Academy of Sciences, 2 Saborna Str., 1000 Sofia; [email protected]
ABSTRACT. The systematic investigations of the Sboryanovo National reserve, which started with the discovery of the Sveshtari tomb in 1982 by
a team of the National Archaeological Institute with Museum, and have been provided till now by the application of a vaste range of interdisciplinary
and archaeometric studies. The aim of the team is to obtain the most exgaustive information about the structure, the chronological frames and the
history of the site and to develop and apply the most efficient methods of excavations and preservation to the Sveshtari tomb and to the whole
complex. The applications of areal photogrammetry, geophysical prospecting, geotecnical knowledge, paleoseismic investigations, geological and
petrographic studies, provenance isotopic analysis, photographic and physiooptic methods, emission spectral analysis, infrared spectroscopy, X-ray
structural analysis, Raman microspectrometry, etc., their effect on the development of new approaches and even for the solutions of some
problems of our modern society has been discussed.
the possible identification of this centre with “Dausdava“, the
“City of the wolves“ on Tabula Nona of the Roman geographer
Kl. Ptolemaios.
The discovery of the Sveshtari tomb in 1982 marked the
beginning of the large scale and interdisciplinary studies both
of the unique monument, which in 1985 was included on the
World heritage list of UNESCO, as well as of its natural and
cultural context (Chichikova, 1992; bibiography of M.
Chichikova’s studies about the tomb see in Dimcheva,
Gaytandjieva, 2008; Gergova, 1992; 1992a; 1998; 2000;
2005). They have been provided till now, although in the recent
years the financial possibilities are much less, unproportional
to the importance of the discoveries and the scientific and
public significance of the discovered monuments (about the
Sboryanovo studies see the bibliography in: Helis, 4, 2004;
Gergova, 2008).
The intensive archaeological investigations which revealed
the main characteristics of this unique Thracian centre lead to
the proclaiming of the Sveshtari tomb as a World heritage
monument in 1985 and of Sboryanovo as a National Reserve
in 1988 (Figs. 1-2). It protects now the remains of one of the
most impressive and important centres of the religious and
political life of Ancient Thrace, belonging to one of the most
famous Thracian tribes the Getae.
The idea about the obligatory stages in the investigations of
a new site was fully materialized in Sboryanovo. The first
phase of the investigations was connected with the study of the
structure of the site and the creation of the fullest possible map
of the area. For the first time in Bulgaria the areal
photogrammetry was applied on a huge territory and a map in
scale 1:2000 of the area was created. The interpretation of the
areal photos allowed to establish the exhistence of a group of
tumuli most probably from the Hellenistic period to the East of
the Great Sveshtari tumulus, destroyed by late medieval
settlement, and thus to give a better notion about the space
organization of the Eastern necropolis. Small settlements from
the iron age and the early Medieval Period have been aslo
registered, thus cmpleting the rchaeological map of the area
(Petrova, 1992).
The aim of the team of the National Archaeological Institute
with Museum was to apply a vast range of interdisciplinary and
archaeometric studies in order to obtain the most exgaustive
information about the structure, the chronological frames and
the history of the site and to apply the most efficient methods
of excavations and preservation approaches to the Sveshtari
tomb and to the whole complex (Gergova, 1992; 1992a;
1992b; 1992c; 1994).
The long term interdisciplinary studies and excavations
clearly revealed the structure of the Thracian settlement
complex, founded in the end of the II mill. BC. It consisted of a
complex of sanctuaries, cult places and several necropolises
of more than 100 tumuli, situated on the two banks of the river,
belonging to the I mill. BC, a Hellenistic town, structures from
the Roman period, several settlements and tumuli from the
Early Medieval. A special attention was paid to the
etnoarchaeological aspects of the site and the survival of the
ritual traditions in the area of the ancient sanctuaries till
modern times. Many arguments support the hypothesis about
The areal results were followed, chequed and accomplished
by the archaeological survey and by geophysical prospecting
(Katevski, Monna, 2005; Katevski, 1992). It was precisely in
Sboryanovo that the views concerning the role and the
maximum effective application of geophysical methods for
367
investigating archaeological sites in general and especially
tumular necropolises were materialized. The geophysical
prospecting was extremely useful for the identification of some
grave structures under totally destroyed tumuli, for the study of
the areas between the tumuli, as well as of the settlements
(Katevski, 2005; Tonkov, Katevski, 2007). New and more
precise methods of excavations were developed and they will
be discussed below.
even the more interesting situation of missing bones and well
peserved precious objects needed a proper interpretation.
Plunderd tombs or specific burial rite? (Gergova, 1992; 1998;
Valeva, Gergova, 2000). How to keep the discovered tombs as
long as possible in their natural miliex?
In world practice the application of geophysical methods for
the needs of archaeology is usually restricted to the detecting
of the anomalous area. The attempt to give the most detailed
possible characterization of the anomalous disturbance
allowed to localize the tombs under the tumuli with a vert great
precision and to apply a new approach in the excavations of
the tombs under tumuli in nearly ideal conditions (Katevski,
1992). Having in mind the exact position of the tomb the
profiles were to cross the tumulus not through the points of the
compass but through its most characteristic features. A
protective curtain of soil, 50 cm thick, had to prevent the tomb
from weather conditions and to give information about possible
later intrusions. More objective possibilities were created for
the study of the rituals which had taken place in front of the
facades of the tombs (Gergova, 1992; Figs. 3-6).
Trial ditches were made on some of the more problematic
sites. Thus the target-oriented archaeology studies could
begin with maximum prelimnary information about the
character of the site as well as for the needs of the planning of
the strategies of the future studies.
The discovery and the later protection activities of the
Sveshtari tomb raised some very important questions both of
scientific and practical character which the team tried to solve
by developing a more efficient methods of excavation and
protection. The existence of many empty tombs in Thrace, or
of tombs with partially preserved bones and inventory, or of
Fig. 1. Plan of the Sboryanovo
reserve
368
Fig. 2. The Sveshtari tomb
Fig. 3. RK-process of excavation of the soil curtain in front of the façade
of tumulus 13
Fig. 5. The entrance of the tomb under tumulus 13 with an iron clamp
fastened by lead
Fig. 4. The tumulus 13 with the entrance and the three layers
corresponding to the stages of the construction of the tumulus
369
The geotechnical knowledge necessary for the construction
of such impressive earth architectural constructions over the
Getic tombs was also studied. The investigations showed that
the piling of the tumuli over the tombs, situated usually in the
3/4th of the radius of the tumulus in its southeastern part, had
been prevously calculated. The tumulus was a complex
geotechnical and earth architectural construction. The first
small tumulus, piled over the tomb, which entrance used to
remain still opened, was covered by small stones – the rests of
the stone working forming a white layer on and in front of it.
This egg-shaped white layer had several functions. From a
practical point of view it was drainig the waters and in this way
preserving the tomb. The next two layers were also
accompanied by the specific treatments of the bones and the
closing of the entrance of the tomb only by the last third layer.
The piling of the tumulus included the formation of well packed
layers of thickness about 40 cm, in order to guarantee the
stability and the ideal shape of the enbankment (Evstatiev et
al., 2005). From an ideological point of view the white layer
was a symbol of purity, allowing to perform the burial rituals
and sacrificies on the clean white surface in front of the tomb.
The egg-shaped form of this first tumulus, piled over the tomb,
was by no doubt a materialisation of the idea about the
cosmic egg, based on more ancient believes, formulated later
by Orpheus (Gergova, 2006).
As a result for the first time a specific principle of three
staged piling of the tumuli, accompanied by three phases of
rituals was recorded, connected with the misterious practises,
mentioned by the ancien authors as “rites of immortalisation”
(Fig. 7). The three staged piling of the tumulus were preceeded
or followed by dispersal and partial reburial of the human
bones, by intentional destruction of some of the objects, by
animal sacrifices and other ritual activities. These practices
were in full harmony with the Orpheus teaching about the
immortality of the soul and the necessity to free the soul from
the prison of the body in order to merge with the eternity
(Gergova, 1996).
The Orphic teaching about the astral immortality of the soul
and the special occupations of the Getic prophets with the sky
was this ideological background of a controversial hypotheisis
about the astronomically determined space organization of the
necropolis. The precision of the map of the area and the
special mathematical-astronomical study of the plan of the
necropolis supported the preliminary observations. The groups
of tumuli were considered to be constructed as mirror
reflexions of some of the brightest constellations. The
archaeoastronomical studies of the orientation of the tombs
revealed the coincidence of the orientation of the axis of the
Sveshtari tomb with the direction of the sun rays during the
winter solstice in the end of IV mill. BC (Gergova, 1992, 12;
Valev 1996; Gergova, Kadijska, 2003; Dermendjiev, 2006)
(Figs. 8-9).
Fig. 6. Tumulus 13; the geophysical prospecting and the localised
anomaly
Fig. 7. Tumulus 12 with the destroyed by the earthquake tomb and the
profile showing the three main stages of the piling of the tumulus
The new method allowed to take preliminary measures and
to prevent the newly discovered tomb from the atmospheric
effect by building the proper protective building during the
excavations and to keep it for a long time in the natural
environment in which it had been preserved under the tumulus
enbankment for more than a millenia (Gergova, 1992).
Fig. 8. The direction of the axis of the Sveshtari tomb
370
Fig. 11. Tumulus 13: symmetrical flaking of the roof blocks lateral
opening of the chamber, due to the born high vertical pressure
Fig. 9. The scene of the immortalization on the NW wall of the Sveshtari
tomb, reached by the sun rays during the winter solstice in the end of IV
c. BC
The different types of distructions, replacements of blocks,
cracks and fissures in the tombs (Todorov et al., 1992;
Christoskov et al., 1995; Gergova et al., 1995) provoked the
providing of paleoseismic investigations of the tombs, and
later – of the walls of the Thracian city (Stoyanov et al., 2006,
65). It was possible to identify a seismic effect of different
intensity on all the tombs in the area (Fig. 10). The
archaeological obserevations allowed to date the earthquake
in the beginning of the III c. BC. The paleoseimic observations
localised its epicentre in the area of Dulovo, NE from the Getic
centre and the strentgh of the event to 7.5 degree of Richter
(Christoskov et al., 1995; Gergova et al., 1995) (Figs. 11-13).
These paleoseismic investigations contributed to the more
objective reconstruction of the historical events in the Getic
centre and for the better understanding of the behavior of the
Getae in such a crusial moment. The fact, that the destroyed
tombs were cleaned from the demolishions, or repaired, and
the tumular enmankments repiled over them, are evidence
both for the special attitude to the tumuli as sacred
monuments, (Gergova et al., 1995) as well as for the continuity
of the life in the town and the area after that.
Fig. 12. Tumulus 13: lateral opening of the chamber, due to the born high
vertical pressure
These paleoseismic studies provided the seismologists with
precious information about an unknown seismic event in the I
mill. BC of one of the seismic centres on the territory of
Bulgaria.
Fig. 13. Location of the Sveshtari necropolis and of the nearest
earthquake epicentres that could have given the pressure deduced from
the damage observed in the tombs
The stability of the tombs under the tumuli and the perfect
preservation of the architectural, sculptured and painted
decoration, as well as of the objects gave ground to develop a
specific approach to one of the most important problems of our
modern society – the deposition of the nuclear wastes. The
archaeological and geological analogues from the geoarchaeological studies of the Thracian monuments could give
more objective data and create a reliable base for the future
constructions of the radioactive waste repositories (Evstatiev et
al., 2004).
Fig. 10. The Great Sveshtari tumulus with the destroyed by the
earthquake tomb; the column in the centre of the tomb is one of the
indicative elements
371
Civilta Abitative. Roma, Ottobre 1993, Annali Geofisici,
907-918.
Coupry, C. 2005. Analyse d’un pigment rose violet par
microspectrometrie Raman. – Helis, 4, 25-28.
Dermendjiev, N. 2004. L’orientation de Demir baba teke. –
Helis, 4, 238-241.
Dermendjiev, N. 2006. Effets des calendiers solaires dans
l’architecture des monuments de culte. – Helis, 5, 169-170.
Dimcheva, D., M. Gaytandjieva. 2008. Bibliography of the
works of M. Chichikova. – In: Phosphorion. Studia un
honorem M. Cicikova (Ed. D. Gergova). Sofia.
Enev, M. 1992. Photographic and physicooptic methods
applied for the investigation of the Thracian tomb near the
village of Sveshtari, Isperih area, Northeastern Bulgaria. –
Helis, 2, 171-178.
Evstatiev, D., D. Gergova, V. Rizzo. 2005. Geoarchaeological
characteristics of the Thracian tumuli in Bulgaria. – Helis,
4, 156-168.
Evstatiev, D, D. Gergova, B. Vachev. 2004. Archaeological and
geological analogues for the safety of radioactive waste
repositories. – Annual Report. Institute for Nuclear
Research and Nuclear Energy, 84-88.
Gergova, D. 1992. 10 years of the Sboryanovo investigations.
– Helis, 1, 9-27 (in Bulgarian).
Gergova, D. 1992a. Interdisciplinary approach in the
investigations of Sboryanovo. – Helis, 2, 9-22.
Gergova, D. 1992b. Studies of tumulus N13 from the Eastern
necropolis of Sveshtari (preliminary communication). –
Helis, 2, 118-126.
Gergova, D. 1992c. Preface. – Helis, 2, 7-8.
Gergova, D. 1994. Preface. – Helis, 3, 7-8
Gergova, D. 1996. The Rite of Immortalization in Anciеnt
Thrace. Agató, Sofia, 268 p. (in Bulgarian with an English
summary)
Gergova, D. 1998. The tumular cemeteries near Sveshtari, NE
Bulgaria – problems and methods of investigations. – In:
2nd Southern-European Conference on Archeometry.
Delphi, April, PACT, 199, 119-121.
Gergova, D. 2000. Sboryanovo – investigations, discoveries
and problems. – Japan ICOMOS Information, 4, 17-24.
Gergova, D. 2005. The Getаe, who immortalize (problems of
the investigation of the Getic necropolis in Sboryanovo) –
In: Tumulus 18. The Hellenistic Necropolis; Getica I, Sofia,
4-12.
Gergova, D. 2006. The tumular embankment in the burial rites
and cosmogony of the Thracian Getae. The cosmic egg. –
ISTROS, 13, 85-94.
Gergova, D. (Ed.) 2008. Phosphorion. Studia in honorem
Mariae Čičikova. Academic Publishing House “Prof. Marin
Drinov”, Sofia (in Bulgarian).
Gergova, D., I. Katevski. 2008. Archaeology and geophysics in
the Sboryanovo National Reserve (North-East Bulgaria). –
In: Geoarchaeology and Archaeomineralogy (Eds. R. I.
Kostov, B. Gaydarska, M. Gurova). Proc. Intern.
Conference, 29-30 October 2008 Sofia, Publishing House
“St. Ivan Rilski”, Sofia, 374-379.
Gergova, D., I. Iliev, V. Rizzo. 1995. Evidence of a seismic
event on Thracian tombs dated to the Hellenistic period
(Sveshtari, Northeastern Bulgaria). – In: Terremoti et
Civilta Abitative. Roma, Ottobre 1993, Annali Geofisici,
919-926.
Ivanov, J., Ch. Pimpirev. 2005. Geological and petrographic
investigations of rock samples from Thracian mounds and
The problems of the provenance of the materials, used for
the construction of the tombs were discussed by geological
and petrographic investigations. They proved the exploitation
of the local quarries and contributed to their precise
localizations (Ivanov, Pimpirev, 2005). A sedimentological
research was carried out in connection with the presumption
that the Demir Baba teke was the tomb of the Bulgarian khan
Omourtag and the stone blocks for its construction were
transported from Pliska. The analysis of the construction
materials of the teke proved their local origin and did not
support the hypothesis (Sultanov, 2008).
Isotopic analysis of the lead clamps from the tombs showed
that the Getae had dynamic contacts with several producing
centres and were importing lead from several mines in
Thassos, Chalcidice, the Rhodope Mountains, etc. (Kuleff et
al., 2006).
The solution of the preservation problems of the Sveshtari
tomb was based on series of interdisciplinary investigations
starting with the geological and seismic stability of the tomb,
followed by the application of photographic and physiooptic
methods to study the effect of the humidity on the destruction
of the stone block’s surface and destructions deeper into the
stone, on the painted decoration, the accumulation of salts and
other processes (Enev, 1992).
The identification of the materials used for the painted
decoration was achieved by the application of series of
investigations like microscopic investigations, emission
spectral analysis, infrared spectroscopy, X-ray structural
analysis, Raman microspectrometry, etc. (Todorov et al., 1992;
Coupry, 2005). The results showed the utilization of ochre and
red ochre, charcoal, lime-wash and Egyptian blue. The origin
of the Egyptian blue is an important indication for the extremely
high possibilities of the Getic royal court to provide the best
materials for the magnificent decoration of their tombs –
monuments of their immortality.
The interdisciplinary approaches to the study of the Getic
religious and political centre were provided with several aims:
▪ to obtain the most exhaustive possible scientific information
for a better knowledge and more objective reconstruction of the
Thracian knowledge, culture, contacts and history;
▪ to develop new approaches not by routine application of well
known methods, but by the development of new trends through
collaboration of scientists in different fields, for the special
needs of the archaeological research;
▪ to contribute by scientific investigation to the solution of the
problems of conservation and preservation in the best and
most efficient way.
These approaches and their results had positive effect not
only on the purely scientific and conservation activities on the
site, but with the obtained information opened new
perspectives even for the solution of some problems of our
modern society.
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