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Eocene Varna Reefs in NE Bulgaria



The Varna microbial carbonate reefs, known as the ‘upright stones’, аrе limestone columns of natural origin, formed in the Eocene sands near the town of Varna, NE Bulgaria. These unique geological formations are among the most impressive natural phenomena in Bulgaria and lie in a protected area of 253.3 hectares which includes 18 geosites of aesthetic and scientific value. Some of these features forme part of the ‘Golden Sands’ Natural Park. The upright stones are bacterial-algal reefs formed within non-carbonate Ypresian sands and silts of the Dikilitash Formation. They are of geomorphological, sedimentological and paleontological interest. Human interest in the columns is a result of their unique morphology, due to which they were originally considered to be the remains of ancient temples and castles. According to various theories, these are weathering or infiltration formations, concretions, coral reefs, petrified forests, etc. At the end of the twentieth century, their genesis was studied in the context of a phytogenetic origin, and it was concluded that they are bacterial-algal bioherms similar to recent atolls and miniatols in modern oceans and seas. In support of this hypothesis is the presence of microbial stromatolite laminations and structures, tubular bodies and algal remains in the columns that are not found in the sediments outside of the columns. The Varna reefs are an attractive tourist destination for visitors of the Bulgarian Black Sea coast. These are included in the UNESCO Programme for the protection of geological heritage of scientific value. The future of these unique geological formations depends on their protection at a national and a European level.
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ISSN 1867-2477
Volume 6
Number 4
Geoheritage (2014) 6:271-282
DOI 10.1007/s12371-014-0120-1
Eocene Varna Reefs in NE Bulgaria
Ivan Nachev & Dimitar Sinnyovsky
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Eocene Varna Reefs in NE Bulgaria
Ivan Nachev &Dimitar Sinnyovsky
Received: 14 May 2013 /Accepted: 15 May 2014 /Published online: 1 June 2014
#The European Association for Conservation of the Geological Heritage 2014
Аbstract The Varna microbial carbonate reefs, known as the
upright stones,аrеlimestone columns of natural origin,
formed in the Eocene sands near the town of Varna, NE
Bulgaria. These unique geological formations are among the
most impressive natural phenomena in Bulgaria and lie in a
protected area of 253.3 hectares which includes 18 geosites of
aesthetic and scientific value. Some of these features forme
part of the Golden SandsNatural Park. The upright stones
are bacterial-algal reefs formed within non-carbonate
Ypresian sands and silts of the Dikilitash Formation. They
are of geomorphological, sedimentological and paleontologi-
cal interest. Human interest in the columns is a result of their
unique morphology, due to which they were originally con-
sidered to be the remains of ancient temples and castles.
According to various theories, these are weathering or infil-
tration formations, concretions, coral reefs, petrified forests,
etc. At the end of the twentieth century, their genesis was
studied in the context of a phytogenetic origin, and it was
concluded that they are bacterial-algal bioherms similar to
recent atolls and miniatols in modern oceans and seas. In
support of this hypothesis is the presence of microbial stro-
matolite laminations and structures, tubular bodies and algal
remains in the columns that are not found in the sediments
outside of the columns. The Varna reefs are an attractive
tourist destination for visitors of the Bulgarian Black Sea
coast. These are included in the UNESCO Programme for
the protection of geological heritage of scientific value. The
future of these unique geological formations depends on their
protection at a national and a European level.
Keywords Lower Eocene .Microbial reefs .Genesis .
Geoconservation .Bulgaria
The geological phenomenon of the Varna reefs,widely
known as the upright stones, is a unique natural formation in
NE Bulgaria, 20-km west of Varna, which has been the subject
of scientific debate for almost 200 years. They are majestic
limestone columns of natural origin, formed among the sands
of the Dikilitash Formation on the bottom of the Eocene sea
about 50 million years ago. The rocks are dated as Ypresian on
the basis of nummulites (Alajova-Hrischeva 1990). The col-
umns are known by different names—‘Dikilitash,standing
stones,stone forest,algal bioherms, etc. and comprise 18
geotops of aesthetic and scientific value distributed over an
area of 253 ha (Figs. 1and 2). The upright stones are among
the emblematic geological phenomena in Bulgaria. They oc-
cur at 5 stratigraphic levels, although in 16 geosites only the
fourth level is revealed, but in Beloslav quarry the lower four
levels outcrop and the fifth level is exposed only near
Strashimirovo village. This remarkable geological phenome-
non has been the subject of a study since the early nineteenth
century. The shape and relationships of the columns with the
host sands haveproduced different hypotheses for their origin,
six of which are abiotic and eight biotic. Some, such as the
remains of ancient temples, weathering formations or petrified
forests now have only historical value. Others have been
reviewed in the light of recent theoretical developments in
sedimentology or transformed into new hypotheses.
Supporting the microbial origin of the columns, the authors
of this paper examine some new evidence from surface
I. Nachev
Geological Institute Strashimir Dimitrov, Bulgarian Academy of
Sciences, Georgi Bonchev Str. Bl.24, Sofia 1113, Bulgaria
D. Sinnyovsky (*)
University of Mining and Geology St. Ivan Rilski,Studentskigrad,
Sofia 1700, Bulgaria
Geoheritage (2014) 6:271282
DOI 10.1007/s12371-014-0120-1
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outcrops, including quarries, and laboratory analyses to con-
firm this theory. However, our main goal is not to prove this
theory but rather to raise awareness of this unique geological
phenomenon and related conservation problems by dissemi-
nating a review of recent work on its origins.
The Concept of the Varna Reefs
The Varna reefs occur in 18 geosites16 natural outcrops and
2sandquarries(Fig.2). Natural outcrops are found in forest
clearings or fields in a stone-gritty landscape where single
columns are available and rarely groups of columns. Due to
natural weathering, columns are reduced in height. They have
eroded surfaces with many secondary features: ribs, grooves,
cracks and gaps inside, as seen in almost all 16 natural
geotops, e.g. Centre North, Centre South and others. With
few exceptions, the reefs have no base, cover and other
primary diagnostic features. Quarries developed between
1960 and 1980 have created a sandy-stony landscape and
reveal columns with primary diagnostic features: e.g. solid
bottom, full height, preserved external contacts, extensions
(kapitel) at the base and at the top, nodules (tumuli), stro-
matolite structures, trace fossils and onkoids. In the Wes t
quarry, 20 protruding reefs at full height (up to 5 m), and 2 to
6 m in diameter remained after sand extraction, with visible
hard grounds, stromatolites, trace fossils, and covers of
nummulitic limestone beds. In Beloslav quarry, a 1-km long
front of white sands and silts is preserved with a total height of
25 m, with four levels of predominantly single reefs
(columns). The columns have a height of 310 m and a
diameter of 0.28m,withextensions—‘kapiteland tumuli,
stromatolites, trace fossils and caver bedslimestones with a
thickness of 0.11 to 5 m for the cover of the fourth level
(Fig. 3). These quarries have provided reliable data on the
composition and morphology of the primary characteristics
and nature of the reefs as organogenic structures.
Brief Characteristics
The Varna reefs are marine structures formed on the bottom of a
shallow Eocene sea during the Ypresian Age, 48 to 53 million
years ago, and exposed in many areas around Varna (Fig. 4).
Fig. 1 Geological sketch map, showing the outcrops of the Dikilitash Formation in the eastern part of the Moesian Platform: 1Dikilitash Formation, 2
geological boundary, 3fault and 4geosites with outcrops of the Varna reefs
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Fig. 2 Map of the geosites with
outcrops of the Varna reefs: 1
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These are real geological structures in the forme of circular or
elliptical single columns or complex biogenic structures of strong
rocks formed among loose sands and silts (Fig. 5). The reefs are
located between nummulitic limestone beds at fifth levels with a
total height of 30 m. The fourth level is covered by a 5-m
nummulitic limestone layer. Above the fifth level, another thick
nummulitic limestone is present. The size of the reefs is 0.2 m
(embryonic) to 10 m. The first level has a height of 10 m, the
second 7 m, the third 5 m, the fourth 36mandthefifth5m
(Fig. 3).Thediameterofsinglereefsisupto2mandofthe
complex reefs, up to 6 m. Internal columns in groups of reefs
have a polygonal section. Contact with the host sands is clear and
sharp with the presence of glauconite and pyrite (Fig. 6).
The reefs have a zoned structure with solid outer zone of
sandy limestone, with gradual transition inwards to calcareous
sandstones or siltstones. The inner zone is white sand and silt; an
internal cavity formed after weathering. In the single columns, an
additional peripheral oncolite zone is formed (Fig. 7). The reefs
grow only on a hard limestone substrate (i.e. solid bottom)as
their base is wider. Rarely, embryonic reefs up to 50 cm in size
are encountered, with conical ends upwards into the sands
(Fig. 8). At the top, reefs pass with extensions (kapitels) into
limestone layers, which serve as a base for the next level (Fig. 9).
They have rings and extensions (tumuli) associated with inter-
nal limestone layers or lenses, which often control the double-
cone shape or forms resembling a throne (Fig. 10a), mushroom
(Fig. 10b) or umbrella. Some reefs start from these layers and end
like sand cones (Fig. 10c).
Lithological composition of the columns is variable. An
external solid zone consists of sandy (and silty) limestone,
passing inwards to calcareous sandstone (or sill stone). The
inner zone consists of white quartz sand and silt. In outcrop,
weathering causes the destruction of the sandy limestone from
the inside and forms secondary longitudinal grooves and
Fig. 3 The most attractive
outcrops of the Varna reefs are in
Beloslav quarry showing the
fourth and fifth levels of columns
with 5-m thick limestone cover
Fig. 4 Outcrop of the Eocene sea
bottom with many miniatollsin
their original distribution among
the Ypresian sands
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transverse cracks. In the now open reefs, rainwater washes the
sand from the inner zone and forms inner (i.e. central) cavity
(Fig. 10d).
The mineral composition of the reefs consists mainly of
calcite and autogenous extraclastic quartz. Under the micro-
scope calcite is observed as a dark cryptocrystalline micrite
and light calcite cement. In the micritic substrate, filaments of
calcareous algae and calcified bacterial aggregates are visible.
These features are evidence of microbial carbonate, formed by
photosynthesis and metabolism of cyanobacteria, hence prov-
ing the marine microbial-carbonate and bacterial-algal origin
of these geological features.
Stromatolites, oncolites and serpulid tubes have
biogenically formed in situ. The stromatolites consist of flat,
dark and light seasonal laminae, determined by microbial
carbonate precipitated by calcareous blue-green cyanobacteria
(Fig. 10e). Oncolites (oncoids) are spherical, irregular bodies
in cluster sizes up to 20 cm, with a core and concentric shells
of carbonate of microbial origin (Fig. 10f). Serpulid tubes
were formed by annelid worms and there is also intense
burrowing bioturbation: these are biogenic structures which
formed independently from the reefs.
Origin of Reefs
The Varna reefs are an impressive, large-scale natural won-
der and a unique geological phenomenon that evokes curi-
osity and admiration. The various hypotheses on their
origin are in tune with the times when they were proposed.
They can be divided into two main groups: abiogenic and
Abiogenic hypotheses explain the formation of the col-
umns due to physical factors without the participation of
organisms. The first record of the Varna Columns comes
from a Russian correspondent from the Russian-Turkish
War in 182 9 (Teplya k o v 1833). He called them the re-
mains of columns of temples or palacesof an ancient
mythical cyclope tribe(Fig. 10g) but also allowed for
their natural origin.
Weathering hypotheses consider the columns to be residual
forms of contemporary processes of weathering that have
occurred under the action of air and water (Spratt 1856,
1857; Toula 1892), surf (Bakalov 1921,1922;Lahn1934),
wind deflation (Gellert 1929,1932), contemporary processes
of weathering (Ehrenberg 1938) and other physical factors
(Ulbrich 1939). A general weakness of these weathering
hypotheses is the absence of other sandstones among the
host sands, making them difficult to prove.
According to the concretion hypothesis of Shkorpil and
Shkorpil (1921), the upright stones were formed as calcareous
concretions within the sands. Another variant of this hypoth-
esis is that they are the result of cementation of calcareous
sand by water through downwards or lateral migration. The
numerous nummulites within the Eocene sediments are ac-
cepted as a source of this CaCO
. Cylindrical, spherical and
tree-like objects are also considered to be nodules, which
formed over a long period of time (Popov 1957,1963,1984;
Haage 1968).
The infiltration hypothesis has also been very popular and
was first proposed by Gochev (1933) and discussed by S.
Bonchev (1934)andE.Bonchev(1970) and explains their
origin with the migration of rainwater. This would penetrate
the limestone cover and mobilize bicarbonate, which then
penetrated more deeply, cementing the sands. According to
E. Bonchev (1949,1955,1970), the formation of the pillars is
similar to the formation of stalactites in caves. However, for
stalactites internal cavities, clastic minerals, glauconite, pyrite
and nummulites as seen in the columns are not typical. The
five levels of reefs with a total thickness of 25 m also refute
this hypothesis.
More recently, methane-derivative hypothesis has been pro-
moted to explain the famous geological phenomena near
Varna. According to this hypothesis, first suggested by Botz
et al. (1993), a key role in calcite precipitation and formation of
the columns was the oxidation of hydrocarbon-bearing fluids
during upwards migration. The relationships between methane
Fig. 5 Reef with oncoids and limestone basement
Fig. 6 Contacts between reefs and in situ sands in Beloslav quarry
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migration and formation of carbonate-cemented sandstone
columns are explained by the strongly reduced δ
C content
of carbonate cement of the columns (De Boever et al. 2006,
2008a,b,2009). According to these authors, the Varna col-
umns are methane seepage-related tubular sandstone concre-
tions, formed by low-magnesium calcite cementation of the
unconsolidated host sediments around the ascending methane-
bearing fluid plume, triggered by the microbial mediated an-
aerobic oxidation of methane. They claim that the vertical
migration of fluids took place along tectonically controlled
pathways, as evidenced by the linear arrangement of the col-
umns, andtherefore, the Paleogene fault system played a major
role in directing fluid movement. As sources of hydrocarbons,
they considered Triassic and Jurassic rocks which had been
penetrated by boreholes in the eastern part of the Moesian
Platform. Studies of these boreholes, however, including the
recently bored R-1 Golitsa (2008) show that the Triassic and
Jurassic rocks in this part of the country are completely devoid
of hydrocarbons.
The analysis of these facts raises serious doubts that are
based on scientific and purely logical arguments. First of all,
cryptocrystalline calcite (sparite) in the cement of the columns
is of biogenic origin, as evidenced by the presence of rare
filaments of algae, bacterial peloids, stromatolites, oncoids,
serpulid tubes and trace fossils. Secondly, most of the faults
are also in post-Eocene formations (see Fig. 1) and therefore,
the fault system could not have played any role in hydrocar-
bon migration during the Eocene. Thirdly, methane migration
from Eocene deposits is in contradiction to the abundance of
benthic fauna among the host sands and the reef structures.
And fourthly, there is no logical explanation of the fact that
these columns are missing among the loose Upper Cretaceous
sandstones of the Shumen Formation, below the Eocene de-
posits, which would also have been on the path of upwards
hydrocarbon migration.
An algal-annelid hypothesis postulates that the columns
area annelid reefswhich cemented sandstones due to the
annelid worms living in symbiosis with calcareous algae
(Pamoukchiev 1996). This assumption overestimates the role
of the annelid worms in the production of such biogenic
structures (Fig. 10h).
The biogenic reef hypothesis explains the formation of the
stone pillars through the activity of coral polyps attached to
the substrate (Radev 1938,1939). However, the colonial
corals do not usually grow on a sandy sea bed and in the study
area; this is confirmed by occasional findings of only solitary
corals in the columns (Fig. 10i).
The hypothesis of the stone forest considers that the col-
umns represent an actual petrified forest (Margos 1960)
formed by the fossilisation of trees or replacement of stems
by terrigenous-carbonate material after rotting under sea wa-
ter. After diagenesis, thismaterial would be cemented forming
a stone forest. Proof of this theory came from traces of boring
bivalves (e.g. Te re d o ) in the columns (Skacel 1963; Panos and
Skacel 1966; Davitashvili and Zakharieva-Kovacheva 1963a,
b; Zakharieva-Kovacheva 1969). The columns, however,
Fig. 7 Peripheral oncolite zone
in the Slanchevo South geosite
Fig. 8 Reef column and embryonic column (left)ofthefirstlevelin
Beloslav quarry
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would be upright, cylindrical pillars of sedimentary material
with central gaps that result from the rotting of the stems. They
are not petrified tree trunks but only preserved by a covering
structuresaround the trunks, consisting of quartz sand and
other minerals with calcite cement (Davitashvili and
Zacharieva-Kovacheva 1975). In reality, however, the outside
of the columns are composed of sandy limestone and sand-
stone with calcite cement. The central cavities are weathering
formations, and the roots of mangrove plantsare invertebrate
trace fossils. The idea of a successive and large scale existence
of five forests in the Ypresian sea (corresponding to the five
levels of the columns) is quite unrealistic.
The hypothesis of algal bioherms is based on the ability of
algae to generate micrite and build bioherms on limestone sea
floors with a carbonate outer zone and inner primary area of
white sand withstromatolites, oncolites, ichnofossils, bivalves
and many benthic fossils (including nummulites, discocyclina
and small benthic foraminifera) (Nachev et al. 1986a,b).
According to the present authors, this view is the most likely,
and the Varna reefs are marine biogenic structures formed in a
shallow Ypresian sea. The littoral zone of this sea is white;
well sorted sands and silts were deposited. Closer to the
shoreline, which was located north of the villages of Banevo
and Slanchevo, sands were deposited, whilst to the south, silt
deposits dominate. In the region where the columns are de-
veloped, sea currents and waves created a firm carbonate sea
bed and provided local conditions for reef development
(Fig. 11). The remainder of the Eocene sea had a sandy bottom
without the necessary conditions for reef-building (Nachev
and Nachev 2001a,b).
The reefs developed as columnar structures that grew up
with the accumulation of sand around them. Emergence and
growth of the reefs passed through three successive phases
(Fig. 12).
(1) On the limestone beds, shallow marine benthic
cyanobacteria biocenoses developed which are
composed of blue-green calcareous algae and bacteria.
As a result of photosynthesis and metabolic activity, they
began forming microbial carbonate (micrite), aragonite
and calcite. Calcite (70 %), mainly in the forme of
micrite is a key mineral for the formation and growth
of reefs. Shallow marine benthic organism attached to
these structures, e.g. calcareous algae, large foraminifers
(nummulites and discocyclina), small foraminifera,
mussels, mud-feeding worms (annelids) and others
(Fig. 10h).
(2) Subsequently, miniatollsarose and started their initial
growth. Their growth was synchronous, as it depended
on the rate of accumulation of sand. The upper part of the
reefs was close to sea level, while the level of the sands
was lower. The interior was filled with sand. Embryonic
reefs are of prematurely terminated development.
(3) Finally, after the complete formation of the columns, they
were covered with a layer of limestone due to the complete
cover of the seabed by reef-building organisms. This is an
excellent example of the process called taphonomic
feedback described by Kidwell and Jablonski (1983)and
Kauffman et al. (1991). The proof of this could be the so-
called kapitelsextensions of columns in their upper part
formed due to the expansion of the reefs due to the re-
occurrence of favourable conditions for benthic organisms.
The rapid colonisation of the entire seabed led to the
formation of biogenic limestone layer. In the Varna area,
these layers separate columns at five levels, indicating a
repetition of this process. These limestone layers also con-
tain larger representatives of the benthic fauna, such as the
oysters, Ostrea rarelamella, colonial corals etc. (Fig. 10i).
After the restoration of sandy bottom conditions, reef-
building was again confined in separate islands, where
some reefs continued to develop to the next level. In other
places, where the newly formed limestone layer is exposed,
new miniatolls developed as columns to the next level
(Fig. 11).
Fig. 9 Kapitels in columns from
Beloslav quarry
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Fig. 10 a Throne-shaped reef.
bMushroom-shaped reef. c
Composite cone reefs on
limestone bed and sandstones. d
Central cavity in circular column
reef. eReef with seasonal
stromatolite lamination and cross-
cutting trace fossils. fOncoids. g
Illustrations of the columns from
Teplyakov (1833). hFossilised
annelid tube worms (serpulids) in
Beloslav quarry. iLimestone with
nummulites and coral
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This genetic model for the origin of the Varna microbial
carbonate reefs is similar to that of recent oceanic atolls but at a
scale of miniatolls (Figs. 4and 12). The evidence is the mor-
phology of the reefs and their structure with an outer limestone
zone and inner zone of loose sands. They differ from typical
atolls in the following aspects: (1) small size, (2) quartz impuri-
ties in the limestone and (3) lack of lagoon sediments (e.g.
dolomite and evaporites) inside them (Nachev and Nachev
In modern environments, similarly, a reef-building occurs
in many places. The most representative examples are the
stromatolith moulds in the Shark Bay, Australia (Riding
2000). In the Bahamas, around more sheltered areas, long,
coarse agglutinated complex columns and domes with com-
plex algal-bacterial covers locally formed. Stromatolitic build-
ings with large agglutinated domes and columns are also
described in the Neogene (Riding 2000).
Despite diagenetic changes, the fossilized Varna reefs have
kept most of the elements of modern miniatolls. Weathering and
erosion, however, has changed or deleted many of them, which
led to the creation of various theories for their genesis.
Weathering processes have begun to destroy the columns from
top to bottom, immediately after the destruction of the covering
younger rocks, including dissolution of carbonate and partial
demolition of their periphery. This led to the formation of sec-
ondary weathering grooves and ribs, and scaling forms
Fig. 11 Facies development and
location of the reefs: 1limestones,
2sands and 3reefs
Fig. 12 Origin and growth of the
reefs: Iinitial stage, II middle
stage and III final stage; 1
limestones, 2sands and 3reefs
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resembling stalactites. After cracking and opening of the bottom
of the columns, rainwater began to destroy the sandstones and
sands of the central part of the columns. This formed the central
cavities, believed in the past to be the cores of tree trunks. Due to
the loose character of the sands, tweathering processes act very
quickly. In the western vertical face of Beloslav quarry, rainwater
and wind have destroyed the white sands and silts between
columns and formed niches over only a few years.
Geoconservation Significance
The Varna reefs are unique geological formations that does not
have complete analogue described from elsewhere in the
world. Their morphology and genesis still provides a great
scientific interest for a third consecutive century. This deter-
mines their extremely high scientific and educational
geoconservation value.
Genetically, the Varna reefs belong to the class of the
geomorphological erosional forms, but they should not be
referred to any of the modern environments (processes and
landforms) reviewed for example by Gray (2004). The
protected area is an island of subarid landscape within an
area of moderate continental climate. Proximity to the sea
makes the climate milder than inland, but typical plants of
arid areas are present, such as cactuses and small
scorpions. This environmental conjunction makes the
area more attractive for modern geotourism in the sense of
Hose (2012).
The proximity of the geological phenomenon to the largest
Bulgarian, Black Sea city of Varna and the Golden Sands resort
provides a great tourist interest which could be developed as
geopark with guaranteed high attendance due to the well-
developed coastal tourism. As discussed by Newsome and
Dowling (2006), accounts of landscape evolution are available
Fig. 13 The centre south area has
been visited by many tourists
since the middle of the twentieth
Tabl e 1 Protected areas of up-
right stones in Varna region Name Settlement Municipality State Forestry Area (ha)
Banovo Banovo Suvorovo Suvorovo 29.1
Beloslav quarry Beloslav Beloslav Suvorovo 30.5
Slanchevo west Slanchevo Aksakovo Varna 79.8
Slanchevo south Slanchevo Aksakovo Varna 33.7
Centre north Slanchevo Aksakovo Varna 0.9
Centre south Slanchevo Aksakovo Varna 16.3
Quarry west Slanchevo Aksakovo Varna 1.2
The Sharp Hill Strashimirovo Beloslav Varna 1.1
Strashimirovo Strashimirovo Beloslav Varna 2.4
Teterlika Beloslav Beloslav Varna 5.3
Beloslav west Beloslav Beloslav Varna 3.7
The naked peak Beloslav Beloslav Varna 2.7
The Avren meadow Beloslav Beloslav Varna 0.5
The apiary Avren Avren Varna 7.7
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of rocks and minerals have been comprehensively described. In
this case, however, it is well exposed unique formations from
Eocene epoch which deserve to be seen by visitors of all over the
world. This could be achieved only within a professionally
designed geopark. Obviously, geotourism here should be focused
on the perfectly preserved original marine conditions and pillar
reef formation. Developing of purpose-built access roads, visitor
centres, interpretive sites, bus tours, bike lanes and hiking trails
will contribute to the future geopark infrastructure.
The central area of upright stones (Fig. 13)isvisitedby
many people, including geologists, geographers, archaeolo-
gists, botanists, as well as tourists, naturalists, travellers and
students. However, the visitor centre in the Centre southand
Centre Northareas with brief and nonprofessional informa-
tion about the columns is not sufficient. The Varna reefs have a
high scientific potential and deserve sustainable protection
and promotion. The protected areas should be integrated into
a national geopark, ideally within a European Geoparks
Network. The great paleontological value of the geosites is
also expressed in their rich nummulitic content, which could
be used for preparing fossil collections for geo-education.
Opening of new visitor centres, discovery centres,interpre-
tative centres, etc., will be a successful supplement to the
sustainable coastal and marine tourism traditionally developed
in Varna region. For this purpose, the creation of a visitor
centre in Varna should be arranged, with a geological museum
and equipment for presentation ofthe geological history of the
region, including the origin of the reefs, biodiversity and
information about the semi-arid landscape, which is unusual
for this latitude.
The first protection order dates for the Varna reefs dates
from 1937, and since then, the status of the area have changed
many timesfrom natural landmarkto a protected area and
part of the Golden Sands Natural Park according to the statutes
of the Ministry of Environment. From 1995 the upright stones
have been declared as protected natural object of international
significance for protection of unique geological formations.
According to the next legal statute from 2002, the area is
reclassified as a protected area under the name upright stones
with a total area of 253.3 ha, but the rock monuments are
united into 14 protected areas with total area of 215 ha
(Table 1). The difference is due to additionally including areas
of the forestry estates of Suvorovo and Varna. In reality, the
total forestry estate, including the protected areas of upright
stones, is 2,965.2 ha of the state forest of Suvorovo and
2,070.9 ha of the state forest of Varna. All this area, including
the 18 geotopes in 14 geosite groups, could be united into a
geopark with total area of 5,036.1 ha.
This protected area is not large enough to stimulate the
local economic activity and sustainable development, howev-
er, but it will be a successful addition and diversification of the
well developed traditional coastal tourism in Varna district and
will contribute to the popularisation of local traditions and the
cultural and historic heritage of the area. In addition, this will
provide a possibility to promote the unique geological phe-
nomenon of the upright stones among the tourists who come
to the area from all over the world.
The development of a national geopark should be made in
the light of the four types of value: intrinsic value, cultural and
aesthetic value, economic value and research and educational
value (Doyle and Bennett 1998), but the economic value
should be restricted to the reasonable use of sand when
uncovering the reefs.
A good initiative should be cleaning of the most represen-
tative geosite in Beloslav quarry for scientific and educational
tourism. This will create conditionsfor the inclusion of the site
in national educational programs devoted to the Bulgarian
natural heritage, for instance, school excursions or, for exam-
ple, a major tour for promoting the geological heritage similar
to the Italian initiative for the promotion of geological heritage
in the secondary schools (Magagna et al. 2013). In addition,
the cleaning of this large area will provide fragments of
columns for the natural museums in the country or, for exam-
ple, arranging open-air museums in schools, universities, etc.,
as suggested by Sinnyovska and Sinnyovsky (2011). This
would be a major step towards a wide dissemination of the
principles and values of ProGEO in Bulgaria.
Alajova-Hrischeva К(1990) Stratigraphy of the lower Eocene sediments
in some of the East Bulgarian plateaus. Rev Bulg Geol Soc 60(1):
Bakalov P (1921) Upright stones (Dikilitash) Varna District. Nature
Bakalov P (1922)The stone pillarsVarna district. Bulg Tour 4(3):3739
Bonchev S (1934) The origin (genesis) of the upright stones
(Dikilitash) or stick upsin Varna District. Geol Balk 1(1):515
Bonchev Е(1949) What we know about the origin of the upright
stones. Nat Knowl 2(910):4143
Bonchev Е(1955) The upright stones. Nature 3:2931
Bonchev Е(1970) Origin of the upright stones. Nat Knowl 67:3037
Botz R, Georgiev V, Stoffers P, Khrischev K, Kostadinov V (1993) Stable
isotope study of carbonate-cemented rocks from the Pobitite
Kamani area, North-Eastern Bulgaria. Geol Rundsch 82:663666
Davitashvili L, Zakharieva-Коvacheva K (1963a) On the origin of the
stone forestnear Varna (Bulgaria). Bull Acad Sci Georgia SSR
Davitashvili L, Zakharieva-Коvacheva K (1963b) Enigma of the stone
forestin Bulgaria. Nature 9:9091
Davitashvili L, Zakharieva-Коvacheva К(1975) Origin of the stone
forests.MetsnierebaТbilisi, pp 196
De Boever E, Swennen R, Dimitrov L (2006) Lower Eocene cemented
chimneys (Varna, NE Bulgaria): formation mechanisms and the
(a)biological mediation of chimney growth? Sediment Geol 185:
De Boever E, Huysmans M, Swennen R, Muchez P, Dimitrov L (2008a)
Controlling factors on the morphology and spatial distribution of
Geoheritage (2014) 6:271282 281
Author's personal copy
hydrocarbon-related tubular concretionsstudy of a Lower Eocene
seep system. Mar Pet Geol. doi:10.1016/j.marpetgeo.2008.1011.
De Boever E, Dimitrov L, Muchez P, Swennen R (2008b) The Pobiti
Kamani area (Varna, NE Bulgaria)study of a well-preserved
paleo-seep system. Rev Bulg Geol Soc 69(13):6168
De Boever E, Birgel D, Thiel V, Muchez P, Peckmann J, Dimitrov L,
Swennen R (2009) The formation of giant tubular concretions
triggered by anaerobic oxidation of methane as revealed by archaeal
molecular fossils (Lower Eocene, Varna, Bulgaria). Palaeogeogr
Palaeoclimatol Palaeoecol 280(12):2336
Doyle P, Bennett MR (1998) Earth heritage conservation: past, present
and future agendas. In: Bennett MR, Doyle P (eds) Issues in envi-
ronmental geology: a British perspective. Geological Society,
London, pp 4167
Ehrenberg K (1938) Gedanken zur Entstehung des Dikili Tasch. Wiss
Jahrb Erst Donau-Dampf schif Ges 1 Wien: 97107
Gellert I (1929) Die Neogenbucht von Varna und ihre Umrandung.
Balkanforsch Geol Inst Univ Leipzig VII Abh math phys Kl Sachs
Ak Wiss 41(2): pp 91.
Gellert I (1932) Die eigenartigen Verwitterunge und Landschefts
formen des Dikilitasch. Sandsteines in Nordost Bulgarien. Geol
Rdsch 23(34):173178
Gochev P (1933) Paleontological and stratigraphical investigations on the
Eocene in Varna Region. Rev Bulg Geol Soc 5(1):183
Gray M (2004) Geodiversity, valuing and conserving abiotic nature. John
Wiley & Sons
Haage R (1968) Zur Petrologie der Kalksandsteinbildungen, genannt
Pobitite Kamani, bei Varna (VR Bulgarien). Geologie 17(4):
Hose TA (2012) 3Gs for Modern Geotourism. Geoheritage 4(12):7
Kauffman E, Elder W, Sageman B (1991) High-resolution correlation: a
new tool in chronostratigraphy. In: Einsele G, Ricken W, Seilacher
A (eds) Cycles and events in stratigraphy. Springer, Berlin
Heidelberg New York, pp 795819
Kidwell S, Jablonski D (1983) Taphonomic feedback: ecological conse-
quences of shell accumulation. In: Tevesz M J S, McCall P L (Eds.)
Biotic interactions in recent and fossil benthic communities. Topic
Geobiol 3 Plenum New York, pp 195248
Lahn E (1934) Der Steinerne Waldvon Varna (Ostbulgarien).
Zentralblatt Min Geol Paleont Abt. B:391394
Magagna A, Ferrero E, Giardino M, Lozar F, Perotti L (2013) A selection
of geological tours for promoting the Italian geological heritage in
the secondary schools. Geoheritage 5(4):265273
Margos A (1960) The wonderful stone forest. State Publishing House,
Varna, p 39
Nachev I, Nachev C (2001a) The upright stones”—bacterial-algal col-
umns. Rev Geol Miner Resour 8(4):6871
Nachev I, Nachev C (2001b) The upright stones”—bacterial-algal col-
umns. Sofia, pp 110
Nachev I, Маndev S, Zhelev K (1986a) The upright stonesalgal
bioherms. Rev Bulg Geol Soc 47(3):113
Nachev I, Маndev S, Zhelev К(1986b) New hypothesis about the origin
of the upright stones. Nature 35(6):1521
Newsome D, Dowling R (2006) The scope and nature of geotourism. In:
Dowling R, Newsome D (Eds.) Geotourism. Elsevier, pp 325
Pamoukchiev А(1996) Reef-building organisms and organogenic
builds from Bulgaria, Algeria, Tunisia and Zair, (Late
Proterozoic, Cretaceous, Paleogene). Autoref doct disert, Sofia
University, 50 p
Panos V, Skacel J (1966) Zur Frage der Entstehung der Steinsaulen
(Pobitite Kameni) und anderer eigenartiger Formen zwischen
Varna und Beloslav in Nordost-Bulgarien. Zeitschr
Geomorphologie N F 10(2):105118
Popov V (1957) Wonderful places of our country. Sofia Technika pp 52
Popov V (1963) Upright stones Dikilitash. In: Our preserves and natural
landmarks. Sofia
Popov V (1984) Genesis of the upright stones. Nature 4:6871
Radev V (1938) Secret of the upright stonesin Varna region-revealed. J
Today N638/17.03.1938
Radev V (1939) The Dikilitash columns of biogenic point of view. Ann
Sofia Univ Phys-Math Fac Nat Hist 35(3):201224
Riding R (2000) Microbial carbonates: the geological record of calcified
bacterial-algal mats and biofilms. Sedimentology 47:179214
Shkorpil G, Shkorpil K (1921) Twenty years activity of the Varna
Archaeological Society, 19011921. Proc Arhaeol Soc 7:384
Sinnyovska D, Sinnyovsky D (2011) Museum exposure of rocks and
fossils from the geological phenomenon upright stones, Varna
district. Ann Univ Min Geol 54:5661
Skacel J (1963) Ke vzniku sloupovitych tvaru Pobiti kamniuVarnyv
Bulgarsku. Zpravy Slozskeho Ustavu CSAV v Oprave Prirodni ved
Spratt T (1856) On the geology ofVarna and its vicinity, and of other parts
of Bulgaria. Q J Geol Soc Lond Proc Geol Soc 12(1):387388
Spratt T (1857) On the geology of Varna and the neighbouring parts of
Bulgaria. Q J Geol Soc Lond Proc Geol Soc 13(1):7273
Teplyakov V (1833) Letters from Bulgaria. Moscow, pp 104112
Toula F (1892) Geologische Untersuchungen im Ostlich Balkan.
Denkschr Ak Wiss Wien Mat-Nat Kl 59(2):409478
Ulbrich H (1939) Ein Steinerer Wald. Kosmos H I Stuttgart
Zakharieva-Kovacheva K (1969) Again about stone forest(Dikilitash)
in the surroundings of Varna. Rev Bulg Geol Soc 30(3):365368
282 Geoheritage (2014) 6:271282
Author's personal copy
... It is composed of white thick-bedded loose, indistinctly bedded quartz sands, calcareous sandstones and thin interbeds of light-beige biomorphic (nummulitic and algal) limestones representing bioherms. In the area of Lake Beloslav, west of the town of Varna, these bioherms form stone columns, which are unique and world-famous geological phenomenon (Nachev and Sinnyovsky, 2014). The chronostratigraphical range of the Dikilitash Formation has been determined as lower Eocene (Ypresian) based on nummulitic assemblages (Aladjova-Khrischeva, 1984). ...
The Paleogene sedimentary rocks in the north-easternmost part of the territory of Bulgaria have been penetrated by numerous boreholes. In terms of regional tectonic zonation, the study area is a part of the onshore sector of the Moesian Platform, which partly includes the South Dobrogea Unit and the easternmost part of the North Bulgarian Dome with its eastern slope. The lithostratigraphy of the Paleogene successions consists of six formal units (the Komarevo, Beloslav, Dikilitash, Aladan, Avren, and Ruslar formations) and one informal unit (glauconitic marker). For compiling an overall conception of the regional aspects (lithology, thickness, spatial distribution, and relationships) of the individual lithostratigraphic units and for illustration of their spatial distribution, a 3D lithostratigraphic model based on reinterpretation of individual borehole sections has been created. The model database was compiled by integration of the original lithological data from 338 borehole sections.
Full-text available
Twenty Italian geological tours have been selected and studied for creating a didactic multimedia product devoted to secondary schools. The aim is to enhance the knowledge of the Italian geological heritage, starting from teachers and students, through the proposal of virtual geological tours. Particular attention has been given both to the relevance of Earth Sciences in everyday life and to the multidisciplinary topics proposed, having care of such aspects as the use of the land and the prevention of natural resources from degradation. An emotional approach has been applied because emotions are essential to stimulate curiosity and to build affection towards a territory, for raising the awareness of the value of the geological heritage. The project required collaboration among researchers, professionals, associations, and institutions involved in studying, protecting, and promoting the Italian geological heritage. Moreover, a further collaboration with teachers and students is foreseen, in order to test the effectiveness of the product in the teaching/learning process. The feedback collected will be useful for realizing a new multimedia product on the geosites of the Piemonte Region, as an output of the multidisciplinary PROactive management of GEOlogical heritage in the Piemonte region (PROGEO-Piemonte) research project.
Full-text available
In the Pobiti Kamani area, up to 10 m high and meter-diameter tubular concretions (so-called columns) are exposed within Lower Eocene sands and sandstones (Dikili Tash Formation) about 20 km west of Varna (NE Bulgaria). These calcite-cemented sandstone concretions have been a subject of many geological studies addressing their formation. In the present contribution a short review is presented as result of a recent (and still ongoing) study about the origin of these structures in relation to past methane seepage. The systematic mapping of the morphology and 2D-spatial distribution of the tubular concretions indicated that: a) the Paleogene structural framework likely played an important role in directing fluid movement to the paleo-seafloor and b) the morphology of different types of tubular concretions was controlled by the subvertical path of ascending gas-bearing fluids through the unconsolidated host sediments as well as by the characteristics of the host lithology and lateral differences in seepage conditions. Based on a detailed petrographical, geochemical and lipid biomarker study, it was furthermore shown that interparticular low-magnesian calcite cementation of the unconsol- idated host sediments around the rising methane-bearing fluid plume, occurred at shallow depth below the seafloor and was triggered by the microbial mediated anaerobic oxidation of methane.
Sequential changes in benthic community composition have frequently been attributed by marine ecologists and paleontologists to autogenic ecologic succession in the classical sense: a biotically driven process leading to the establishment of a stable climax or mature community (Margalef, 1968; Odum, 1969). In recent years, however, the concepts of deterministic autogenic succession have been modified and supplemented by a greater recognition of the roles of stochastic colonization and of biogenic and physical disturbance in structuring ecological communities in time and space (Colinvaux, 1973; Drury and Nisbet, 1973; Sutherland, 1974, 1981; Horn, 1974, 1976; Connell and Slayter, 1977; Connell, 1978; Lubchenco, 1978; Sousa, 1979a, 1980; White, 1979; Paine and Levin, 1981). Paleontologists have also begun to adopt a more critical approach, recognizing the many processes, both biotic and abiotic, that serve as driving mechanisms for sequential faunal changes.
Since the initial recognition and definition in the early 1990s of geotourism in the UK by a few academic geologists, and its emergence in Europe as a niche form of sustainable tourism, new stakeholders have become involved; the latter’s background is often commercial and lacking in any significant academic or scientific engagement. Consequently, the geosite/geomorphosite management and promotional approaches they adopt are usually founded on practitioner and supply side led approaches rather than the geoconservation requirements of geosites/geomorphosites and the needs and expectations of their geotourists. This is probably because the new stakeholders have limited knowledge and understanding of the relevance of the history, development and philosophy of landscape conservation and promotion (that is geohistory), and the lessons that can be gleaned from such considerations in managing and promoting geosites. This paper seeks to redress this situation by providing an outline of the historical and theoretical underpinnings of geotourism and approaches to its sustainable management. It especially examines and defines, underpinned by UK examples, three key interrelated aspects (the ‘3G’s’) of modern geotourism: geoconservation, geohistory and geo-interpretation. It further updates a prior published geohistorical model and provides a new summary topology and a geotourism chronosequence. Finally, it addresses, within the framework of the new definition and its approach, some of the issues generated by the development of geoparks in Europe in the first decade of the twenty-first century.
Varna and the Coasts to the South.—The Varna district seems to consist generally of two distinct formations: viz. 1st, a series of yellowish and grey deposits, composed of calcareous sandstone and sandy marls, with sometimes an oolitic bed interstratified; 2ndly, a series of arenaceous marls, sands, and fine gravel, of a reddish-brown and greyish colour, which overlie the former, and occupy the tops of the ridges, or occur on the sides of some of the valleys. The lower group is marine and appears to be of the Eocene Tertiary age; it attains a thickness of fully 1000 feet in some localities. The overlying red sands and marls are seldom found in greater thickness than from 100 to 200 feet in the immediate vicinity of Varna; having been no doubt much denuded from that district. On the coast, however, at Cape Aspro, about fifteen miles south of Varna, and ten miles north of Cape Emeneh, the termination of the Balkan, the cliffs show a section of the two series of deposits together, as seen in the following sketch (fig. 1). A local disturbance has here tilted the two formations to a greater inclination than usual, and exposed a thickness of fully 1000 feet of the red sand and marls.
Capt. Spratt first noticed a series of whitish calcareous sandstones and marls, seen on the Bulgarian coasts; these are nearly 1000 feet thick, and are overlaid by reddish sands and marls. The former are of marine origin and of Eocene tertiary date; the latter are chiefly of freshwater origin. Near Varna the freshwater beds have been much denuded, and are not anywhere more than 200 feet thick. At Cape Aspro, fifteen miles south of Varna, both of the series—the grey and the red deposits—are seen disturbed and dipping to the south, but unconformably, one series (the lower) having an angle of 30°, whilst the upper dips at 20°. At Cape Emineh, south of Cape Aspro, and forming the termination of the Balkan, these beds are still more disturbed and dip to the north. Capt. Spratt then described the geological appearances along the coast southward. At the Gulf of Bourgas and in the vicinity are igneous rocks, and deposits formed from their waste. Granite occurs on the southern point of the bay.
Up to 10m in length and >1m in diameter tubular, calcite-cemented sandstone concretions are hosted by the faulted Dikilitash unconsolidated sands and sandstones. These structures document shallow subsurface pathways of Early Eocene methane seepage in the Balkan Mountains foreland (NE Bulgaria). Their exceptional exposure allowed a unique study of the factors governing the morphology and spatial distribution of such fossilized fluid conduits. The large dimensions and subvertical, cylindrical shape of the most common tube type primarily reflects the buoyancy-driven, vertical path of an ascending gas-bearing fluid through permeable, mainly unconsolidated sandy host sediments. Tube morphology was also influenced by local stratigraphic anisotropies and might as well document differences in former seepage conditions. Mapping of >800 tubular concretions showed the NNW–NNE elongation and alignment of tube clusters and massive cemented sandstone structures. This suggests that Paleogene fault systems played a major role in directing the movement of fluids. However, within a single tube cluster, tubes are preferentially aligned, over distances up to 50m along directions at an angle between 10° and 36° with respect to the inferred NNW–NNE, cluster parallel fault traces. In addition, cylindrical tubes of analogue dimensions are aligned over distances >100m along N15° to N25°-oriented directions. It is hypothesized that this spatial geometry of tubular concretions reflects the complex geometry of deformations structures in fault damage zones along which fluids were preferentially channelled.
Impressive, several meters high tubular concretions in shallow marine calcareous sands and sandstones represent part of the well-exposed, subsurface plumbing network of an Early Eocene methane seep system in the Balkanides foreland (Pobiti Kamani area, Varna, NE Bulgaria). An integrated approach, including petrography, inorganic geochemistry and lipid biomarker analyses was used to reconstruct the evolution of pore fluids and cementation conditions during tube formation and particularly, the role of methane-related carbonate diagenesis. Host sediment lithification from marine pore waters was perturbed soon after deposition by oxidation of predominantly microbial methane causing pervasive cementation by a 13C-poor, homogeneous calcite cement (δ13C values as low as −44.5‰ V-PDB). The importance of microbially mediated anaerobic oxidation of methane (AOM) is confirmed by extremely 13C-depleted archaeal biomarkers (δ13C values as low as −123‰ V-PDB). A suite of macrocyclic dialkyl glycerol diethers (MDGD-0 to -2) and sn-3-hydroxyarchaeol comprises a characteristic trait of the Eocene tubular concretions and might represent molecular fossils of so far unknown methane-oxidizing archaea (ANME). Subsurface calcite cementation surrounding the ascending methane plume, resulted from the changing pore water chemistry in response to AOM and could have, on a local scale, been encouraged by the concurrent alteration of detrital feldspar. Fluctuating δ13C (up to −8‰ V-PDB) and δ18O (−0.5 to −9‰ V-PDB) signatures within a single tubular sandstone concretion are at least partly the consequence of isotopic resetting during late meteoric water circulation.