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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, 163-168.

GEOLOGICAL AND MINERALOGICAL BACKGROUND OF THE MEGALITHIC AND ROCK-CUT SITES IN BULGARIA AND SOME OTHER EUROPEAN COUNTRIES Ruslan I. Kostov

University of Mining and Geology “St. Ivan Rilski”, 1700 Sofia; rikostov@yahoo.com

ABSTRACT. The leading role of the geological and mineralogical, and not the geomorphological background has to be stressed in the distribution of the megalithic and rock-cut monuments. Megalithic sites in Europe (in the cases of Bulgaria, Great Britain, France, Portugal and Spain) display a tendency to be linked to a specific geological setting of the region. They are built mainly at places of distribution of quartz-bearing igneous (granites) or metamorphic (gneisses) rocks. Usually their composition is of the same rock species, but in some cases the rock blocks have been transported from remote areas. White vein quartz blocks are also considered of importance at such sites. Rock-cut trapezoidal niches on high vertical cliffs, holes and graves in the Eastern Rhodopes in Bulgaria are related mainly to regions of distribution of volcanic (including volcanic tuff) or sedimentary (limestone) rocks. Such a tendency may be observed in certain other places in Europe and worldwide. Other geological (geotectonic), geographical features and physical (including acoustical) properties of the rocks are also to be considered important for interpretation of the megalithic culture in future research.

Introduction The megalithic and rock-cut monuments are linked to the development of human civilization since its origin. These monuments have a key significance throughout the centuries in different regions and countries around the world. For some of them the discussion about their fuction, transport and construction continues, as well as for their age and importance for ancient civilizations. A lot of the ancient technologies are not yet recognized by contemporary engineering and scientific thought and some of them are considered even difficult or impossible for the present technical possibilities of humankind. The megalithic monuments are usually related to large rock blocks which have been moved from their original location and in most cases have been later partly of fully formed. Among the megaliths can be listed a number of architectural forms as menhirs (standing stones), dolmens (stone “table” or stone “house”; usually a rectangular space formed by big rock slices with or without an entrance passage and a barrow above), cromlechs (stone circles), alignments (rows with large stones) and cyclopic buildings (walls, temples, fortresses etc.). Megalithic sculptures are represented by giant stone-cut figures (for example the two quartzite statues 750 t each of Amenhotep III transported at ~680 km distance in Ancient Egypt, or the numerous elongated large volcanic ‘heads’ on the Easter Island). Some giant rock blocks can be seen in the ancient quarries even today – such are the cases in Baalbeck in Lebanon and the Aswan quarry in Egypt (for examples see also Kukal et al., 1989; Kostov, 1998). The rock-cut monuments represent the “negative” approach to the rock or stone – cutting and disintegration. Such monuments are for example rock pits (cups), holes, niches,

circles, steps, borders, thrones, chambers, corridors, temples, tunnels, labyrinths and other architectural forms (Kostov, 1993; for an early classifcation of ring and cup marks c. Reader, 1891, 2-3; for their metrology including the “megalithic inch” – Thom, Thom, 1978). Since prehistoric and ancient times two types of sacred attitude towards the rock (stone) or the mountain can be traced. The first one is as a lithic totem, where the rock or stone is believed sacred and associated with a group or tribe, and the second one is as lithic idol (amulet), where the sacred object introduces a single individual (Kostov, 1993, 30-36). The uniqueness of the object is regarded as some real or imaginable important characteristic or property (morphology – crystal habit or interesting mineral aggregate; physical property – colour, hardness, transparency, lustre etc.; chemical property; cut) or place and position in nature (mountain peak; peculiar rock form; entrance of a cave; rock hit by lightning etc.). The aesthetic view of humankind towards stones (minerals and rocks) and bioobjects becomes the object of study of gemmology (in the case of archaeological artefacts – archaeogemmology). Two opposite tendencies can be traced in describing rocks and rock-cut monuments of culture – a “positive” and a “negative”. The megaliths represent the first tendency with the expression for building and constructing architectural forms imitating the “holy” rock or mountain. In this case we see also examples of building stone towers, columns, obelisks, pyramids, walls and whole cities. The extreme case is the lithic gigantism – cutting, transporting and using of giant rock blocks or statues. The second tendency, as already discussed, is related to the rock-cut monuments. This tendency is linked to the primitive belief for finding shelter in nature (away from

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natural disasters, wild animals or enemies) – usually rock shelters and caves. The extreme expression of this tendency we find in the contemporary underground mines, military bases and war shelters, as well as different kind of transport and communication tunnels. In this respect is interesting to trace the nature and distribution of the different troglodyte cultures throughout the centuries (Reverski, 1996).

Geological position of megalithic monuments Bulgaria The megalithic groups are located in the Sakar and Strandja Mountains (megalithic sites are known also in Northern Greece and the European part of Turkey). Some of the pioneers of Bulgarian geology and archaeology have described mainly dolmen sites in Bulgaria (Bontscheff, 1896; Bonchev, 1901; Škorpil, 1925; Mikov, 1932; 1933; 1936; Velkoff, 1938). A characteristic of the monuments is their beautiful landscape setting, and it is pity that a lot of them have been destroyed during the last century. Most scholars date the megalithic monuments to the Iron Age (1200-500 BC) on the basis of excavated finds (c. Thracian Monuments, 1976; 1981; Fol, 1993; 1997; 1998; 2000; 2007 and the cited earlier literature), but there is a suspicion that some of the sites may well date to an earlier period (Zacharieva, 1999; Kostov, 2004), perhaps even to the Chalcolithic (5000-3500 BC) in Bulgaria. With the closest megalithic group located in the Crimea Peninsula and the Caucasus Mountains, the “Bulgarian” megalithic group is unique to South-East Europe. In Bulgaria the main distribution of described dolmens (only a few new sites have been excavated and published) has been related to two main regions – in the Sakar and the Strandja Mountain. In both cases the host rocks are mainly granites and in some cases – gneisses (both are quartz-bearing rocks)

(Kostov, 1994; 1998 and the cited earlier literature; see also Kostov, 2004; 2005; Fig. 1). It has been observed that especially in the Sakar Mountain region a lot of white quartz blocks were found around the megaliths, which may have been used for some purpose in the decoration or building the dolmens or on top of their barrows. The dolmens are located in a course-grain granite region with a lot of white granular quartz veins. It is well known that the course-grain granite has a higher radioactivity background compared to medium- or fine-grain granite. Some other dolmens and related structures are known also in the Sredna Gora Mountain region (in granites; for example Buzovgrad), the Hukhla Height (at Ostar Kamak, near the town of Harmanli) South of the Maritsa River (in gneisses), the Dervent Heights (in granites) near the Greek border, in the Burgas region near the Black Sea (from the village of Rosen on the North across Meden Rid to the South) and in the most Southern part of the Eastern Rhodopes among the metamorphic Precambrian complex (from the village of Chernichevo on the West to the villages Zhelezino and Pelevun to the East, near the Greek border; some dolmen sites are known also on Greek territory in the same region of the Rhodopes). Other geological and geographic characteristics for the location of the megalithic sites have been suggested to be taken under consideration as: geotectonic setting; seismic zoning; sunshine activity; climatic peculiarities; areas of thunderbolts and hailstones; local background radioactivity (related to the rocks) and geomorphological (landscape) location and orientation (Kostov, 2005).

Fig. 1. Geological map and dominant localization of megalithic (mainly dolmen) sites in the Sakar and Strandja Mountain in SE Bulgaria in regions with quartz-bearing rocks (granites and gneisses) (Kostov, 1994; 1998): 1 – Quaternary, alluvial sediments; 2 – Neogene and Paleogene, sedimentary rocks; 3 – Upper Cretaceous, sedimentary rocks; 4 – Upper Cretaceous, igneous rocks; 5 – Jurrasic and Triassic, sedimentary rocks; 6 – Paleozoic, sedimentary rocks; 7 – Paleozoic, granites; 8 – Precambrian, metamorphosed granites; 9 – Precambrian, gneisses, schists, amphibolites and quartzites; 10 – one or more megalithic sites; 11 – Black Sea; 12 – border with Turkey

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Other European countries Similar pattern of distribution of the megalithic sites and the host local geological setting (granites or gneisses) has been described for Great Britain and Ireland (geological setting from Atlas géologique, 1980; megalithic sites after Chippindale, 1983; see Kostov, 1995; 1998). In the Cornwell Peninsula, there is a very good match between the location of megaliths and granitoid rocks (Fig. 2). In Scotland megaliths are represented mainly in areas with granites and metamorphic rocks (gneisses) and in Ireland – in areas with granites or sandstones. White quartz blocks have been inserted in the solar “window” of the Newgrange megalithic site in Ireland (the passage and chamber are illuminated by the winter solstice sunrise) – they are brought from the Wicklow Mountains 40 km to the South, and the rock igneous and metamorphic slabs – from the Newry Complex ~25 km to the North (O’Kelly, 1982).

Fig. 2. Distribution of megalithic sites on the British isles (Chippindale, 1983); examples of clustering at the Cornwell Peninsula, Island of Arran, Eastern Scotland and Northern Ireland – areas of granite and other quartz-bearing rock outcrops

In Scotland there is a lot of data for the possible use of white quartz pebbles in megalithic sites in some sort of a Moon ritual (Welfare, Fairley, 1980, 145). The same authors mention the presence of “strange discs of shining white quartz” found after excavations among some cromlechs in Northeast Scotland. The observation of distribution of megalithic sites on the map of France shows that they are grouped mainly to the West in Brittany along the sea coast and spread to the Southeast in the mountain areas at the Mediterranean coast (Bily, 1999). The region around Carnac in Brittany (Bretagne) is famous with menhirs, a lot of dolmens and a number of unique stone alignments (Mereaux, 1992; Briard, 2000; Strong, 2001). The main rocks are granites and the megaliths have been built mainly from granite slabs (c. Migon, 2006, 328-330). In the Carnac area the orientations of the dolmens (average 116o) coincide with the orientation of the fault lines (average 117o) and certain suggestions have been made linking the megalithic structures with seismic activity, electric, magnetic and gravitation anomalies (Mereaux, 1992, 49; Strong, 2001, 5). The geological map of France (Carte Géologique, 1996) clearly displays that the North-West to South-East diagonal distribution of the megaliths is under the “control” of acid intrusions of other quartz-bearing rocks (Fig. 3). Almost no megaliths are to be found in the vast territories of the Paris basin to the North-East or of the Aquitaine basin to the South-West. In the corridor of the dolmen passage on the Island of Gavrinus two blocks of pure quartz have been used with very faint traces of carving and brought from a distance of 10 km (Mereaux, 1992, 169; Strong, 2001). Portugal is also famous with a lot of megalithic monuments which have been grouped on the corresponding map of their distribution in several fields – Evora, the Viseu area, South of Chaves, the extreme North-West, Sintra and Sagres (Bily, 1997). Comparing the megalithic sites with the geological setting of Portugal (Atlas géologique, 1980) one can find a tendency for overlapping distribution of megaliths and acid intrusive (granite, granodiorite, tonalite) or other quartz-bearing rocks (Fig. 4).

Fig. 3. Distribution of megalithic monuments (left) in France and location of acid intrusive (granite) or metamorphic (mainly gneiss) rocks (right)

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Fig. 4. Distribution of megalithic monuments (left) in Portugal and localization of acid igneous intrusive (granite, granodiorite, tonalite) and volcanic rocks (right)

Similar is the location of megalithic sites in Spain with clustering of such sites mainly in the North-West part of the country (Fig. 5). At the Alberite dolmen in Andalusia (Cadiz Region) in Southern Spain a large up to 20 cm rock crystal has been found with suggested magic functions (Domínguez-Bella, Morata, 1996; similar quartz prismatic crystals have been found in other dolmen sites in the country).

Fig. 5. Distribution of the larger megalithic areas (a single black dot corresponds to a large number of megalithic sites) in Spain – mainly in NW Spain (Galicia and Asturias) and NE Spain (Cataluna), linked to a granite geological setting

In the Crimea Peninsula and the Caucasus Region (Markovin, 1978; 1997; 2000) there is also a geologically linked tendency for the distribution of dolmens (part of them is granite-controlled – for example in the Maikop area or to the North of Sukhumi in Abkhazia) (Kostov, 1994; 1998). In the rest of the cases probably the dolmens are built by sedimentary rocks as in the case of the Zhane Valley – quartz sandstones with a high quartz content (two types: light yellowish in colour with 20-30% quartz composition and hard, dark grey with quartz composition more then 50%; personal communication by Dr. V. Trifonov – St. Petersburg, Russia; c. Markovin, 1978, Fig. 20). It has also been discovered that the main group of dolmens in the Western Caucasus is linked in most cases to large faults (Furdui, 2005, Fig. 23).

Acoustic properties can be found at the perimeter of the chambers of the dolmens, which were measured for a number of the Caucasus megaliths, revealing three main groups: 472 cm, 720 cm (largest group) and 1035 cm, corresponding to resonance frequencies of 35, 23 and 16 Hz near the ultrasonic region (in which certain internal and brain effects can appear when such low frequencies are applied to human beings; Furdui, 2005, 158-159, Fig. 22). Similar research at Neolithic sites around the British Isles has revealed striking similarities in some of their acoustical properties with key examples being the huge passage tomb of Newgrange and the burial mound known as Cairn L at Loughcrew (both in Ireland). These sites contain passageways leading to large circular chambers, and have a resonant frequency (at which sounds naturally echo and reverberate) of about 110 Hz, probably inducing physiological and psychological changes in people during chanting, singing or drumming (Pilkington, 2003; for earlier studies of acoustic properties of megalithic sites see Watson, Keating, 1999; Devereux, 2001). The observed tendency of linking megaliths to the quartz-bearing (mainly granite or gneiss) geological background has to be carefully applied in remote places where different cultural influences may have taken place, including South East Asia or the Pacific Region (Lansing, 1987). The distribution of megaliths (mainly dolmens) in Korea (the whole Korean Peninsula as well as the Shandong Peninsula in China and for the South of Japan – the Eastern part of Kyushu Island; Byon, 2000) confirms the main idea for their location mainly on a granite type quartz-bearing background. A second geological problem in the study of megalithic monuments is the precise mineralogical and petrographical determination of the type of rock blocks or pieces used in such constructions. Usually there is a concurrence between their composition and the local geology, but in a number of cases some or all of them have been transported from distant quarries. A classical example in this respect is the Stonehenge megalithic site in England with a number of different large rock species, some of them being brought as far as the Preseli Mountain in Southern Wales (for review see Green, 1995).

Geological position of the rock-cut monuments The rock-cut “concave” (negative) stone monuments are reviewed as typical in their distribution for regions with volcanic and sedimentary rocks with a lot of examples in the Eastern Rhodopes in Bulgaria (rock-cut cups, niches, rock tombs, as well as other architectural types). Famous for Bulgaria are the “Madara Horseman” rock bas-relief on vertical limestone cliffs in North-East Bulgaria (UNESCO heritage site) or the Aladja Rock Monastery in a limestone near the town of Varna. Some of the most famous rock-cut temples in India (Ajanta; Elora; Elephanta) have been cut in hard volcanic rocks (see other examples in Kostov, 1998). The occurrence of volcanic rocks and the lack of acid intrusive rocks on the main part of the Apennines (without areas in the most Southern parts) or along the Adriatic coast of the Balkans in Europe explain the lack of megalithic type structures in such geological setting (an opposite tendency one can observe on the near-by islands of

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Corsica or Sardinia – in the second case with its Nuragi stone-building culture). An example of the tendency for relation of rock-cut monuments to sedimentary and volcanic rocks are the enigmatic trapezoidal niches, known in hundreds of numbers cut high on vertical cliffs in the Kurdjali and Haskovo Regions in Southern Bulgaria (with no analogue of the shape in the Balkans or elsewhere in Europe). Their function has been also under discussion (“places for votive objects for the dead”?), but their geological background is linked dominantly to certain places along rivers with a geological setting by hard to very soft volcanic rocks and tuffs, and in places – limestones (one exception is known near the town of Ardino in the Central Rhodope – the “Eagle’s Rocks” site is located in metamorphic rocks) (for all the hypotheses and size description see: Kostov, 2001).

Conclusion The leading role of the geological and mineralogical, and not the geomorphological background has to be stressed in the distribution of the megalithic and rock-cut monuments. In each case these rock monuments have to be related to a certain population. Most of the megaliths in Europe (in the cases of Bulgaria, Great Britain, France and Portugal) show a tendency to be linked to the geological setting of the region. They are built on the place of distribution of quartz-bearing igneous (granites) or metamorphic (gneisses) rocks. Usually their composition is of the same rock species, but in some cases rock blocks have been transported from remote areas. Rock-cut niches, holes, rock-cut graves and a whole rock-cut ancient town (Perperek) in the Eastern Rhodopes in Bulgaria are all related mainly to regions of distribution of volcanic or sedimentary rocks. Such a tendency can be observed in other places in Europe and worldwide. The ‘hidden’ plutonic (usually quartz-bearing granite) rocks are raised and hipped on the Earth’s surface, and on the contrary, the erupted on the Earth’s surface volcanic rocks (usually of a darker colour, because of the content of mafic minerals) have been cut and disintegrated. This dualism of up-down, Sky-Earth, white-black, light-dark, in-out, day-night and similar oppositions have to be considered in the cosmogonic and other mythological systems of thinking among the ancient population with its lost heritage – the hidden “rock philosophy”. References Atlas géologique du monde. Geological World Atlas. 1980.

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