From the sanctuaries documented so far in the Rhodopi mountains Harman Kaya is the most impressive one. It is located in the region of village Dolna Chobanka, Momchilgrad County. The site has been registered more than 60 years ago (Mikov 1941). The sanctuary developed on a not-very-high plateau around a 7-meter long, small natural cave. In front of the cave on the surface of the terrain is located the largest heaping of ceramic fragments. The earliest ceramic fragments date from the late Chalcolithic epoch, and the latest - from the 1st-2nd c. AD. Trapezoid niches are hewn in the vertical rock located next to the cave's entrance. There is another karst cave located at the foot of the plateau. It is 20 meters long with traces of cultivation.
The plateau where the cave is located is crowned with rocks. It dominates over the environment and is naturally fortified. The inner sacred space includes the rocky top with the cave. One entered the sacred space through a cleft between the rocks which was secondarily designed as an entrance. The entrance was closed with a door the threshold and grooves of which are still recognizable in the rocks. The terraces cut in the rocks and defined also for sun observation usage, the foundations of chambers, stairs, sacrificial pits, altars, basins (probably including purificational ones) are located in the outer sacred space. The rain water was directed outside the chambers via outfalls cut in the horizontal rocks. Rocks with hewn in trapezoid niches and sacrificial altars rise in this outer sacred space.
Two grounds, evened out, with diameters respectively 10 and 15 meters, are located in this space (Fol, V. 2000; 2003). The first one, marked as northeastern, has an oval shape tilted slightly to the North. 6 concentrated semicircles separated by 0.3-1.4 meters are formed through hollowing the rock. Their diameter, of course, constantly increases. A throne, turned east-northeast is hewn in the rock in the western end of the ground. The second ground has an almost circular shape. It is marked as southwestern, and has 11 concentric semicircles. The ground itself is slightly inclined south. A throne is hewn in the northern side of this ground and is turned northeast.
According to the sanctuary's discoverer, Prof. V. Mikov, the remains of "the biggest Thracian city" are apparent at Harman Kaya's foot. Not only the outlines of the chambers are obvious, but also the streets and the squares. The masonry, according to the author, has no mortar, and the ceramics which he discovered at the terrain, dates between the 6th and the 1st c. BC.
A tomb is hewn in the rocky slope above the river, next to the cult place. For now there are no data the cult complex Harman Kaya functioned in the Middle ages, thus diferring from other rock-cut cult locations.
The archaeo-astronomical research of the two terraces hewn in the rocks (one of them being circular), shows that they likely served for measuring the yearly cycle and for establishing of the summer and winter solstices. Research proves that the rock mega-complex intended for such solar observations was created around 2000 BC. (Stoev, A. and others 2003).
Author: Valeria Fol.
The Harman kaya rock-cut sanctuary is situated at a place with the same name, two kilometers north-east of the Gasak hamlet, the village of Dolna Chobanka, Momchilgrad Municipality. The rock-cut complex is developed around a little natural cave (Mikov, 1941). At the entrance of the cave a pottery from the Eneolithic Age is found. At the two sides of the entrance two trapezoidal shaped niches are hewn in the rock. The monument had not been studied till now by the means of systematic archaeological and geophysical methods. An information about it give Raduncheva (1990), Nikolchovska et al. (1996) and Fol (2000).
The Harman kaya country is a rock massif with a dominating above the neighborhood relief. The rock is red shaded, composed of rhyolites and volcanic tuff. The vertical walls of the south-western, south and east slope rise above the adjacent negative forms to about 50-80m. An excellent view both to the east and west horizon line opens from the upper parts of the rock massif. At different parts of the rock-cut complex one can see the well outlined walls of several rooms and little circle and rectangular reservoirs.
Two well leveled rock grounds dominate in the general plan of the rock massif. First of them (north-eastern) is about 10m in diameter and has a slight slope to the North (an average of 16grad). The second one (south-western) is 15m in diameter and the slope is to the South (an average of 28grad). These grounds are the reason for giving such name of the rock-cut complex. Harman kaya means the place of the rocky grounds (from Persian harman- place of threshing).
Concentric semicircles with a distance of 0.3m÷1.4m between their contours are hewn on the grounds. The diameters of the semicircles lie in the main meridian plane and progressively decrease. The first ground has 6 semicircles in North direction and the second � 11 semicircles to the South. Semicircles of the two grounds are cut by rock engravings.
Morphology and tectonics of the adjoining geographic region
The Harman kaya rock-cut megacomplex is formed in part of the Nanovitsa caldera, which is part of the Oligocene and Eocene Strumni rid volcano vault morphology structure. The object is part of the inner caldera-lowering boundary. Frequent tectonic movements change has a basic significance in the geological development of this morphological structure. According to recent research, the tectonic processes in this part of Bulgaria have a positive tendency. Geological evolution continues up to receiving a new impulse of tectonic activation during the neotectonic stage, which provokes final building of the region's morphotectonic view.
This determines the strong crack structure of the basic rock, building the Harman kaya massif, as well as the formation of tectonic caves of different size. Some of the wider fissures today exist as tectonic caves of different sizes, which obviously were indivisible part of the rock-cut megacomplex in the Antiquity. Two of them are larger than the others � the upper cave is 7m long and the lower one is 20m long. The averaged azimuth of their main axes is 394grad (i.e. close to the North � South direction). Research of 1800 fissures in the net of tectonic cracks in the rock's main volume shows a predominant development of the main fissure system exactly in this way, with an azimuth within the range 395 ÷ 5grad.
This fact proves the strong connection of the current geological formation - Harman Kay megacomplex and its basic tectonic movements during preceding geologic periods. The secondary rock massif denudation additionally formed typical karst negative and microrelief forms � karren, karrenfields, pits etc. Cracks' distribution investigation on both the area of these artificially leveled grounds and on the territory of the adjacent terrain shows that cracks are uniformly distributed on the areas in the frames of the statistical error. Only the size of the karst forms (width and depth) is different at the two kind of places. It is smaller at the levelled grounds, which confirm that they are of artificial origin.
Archaeoastronimical research and interpretations
Geographical co-ordinates of the Harman kaya rock-cut megacomplex are determined with the help of GPS receiver and several consecutive observations of a Ursa Minor with a precise Theo 010 theodolite, with a direct accuracy of 2cc: λ = 25°30'59", φ = 41°34'26". The altitude of the highest point is also determined � 428m. Orthogonal and tacheometrical plans of Harman kaya complex are made using theodolite. By the method of segment photographing, for the north-east ground, near and far horizons are outlined and the local zones, which coincide with the places of sunrise at the vernal and autumn equinox and summer and winter solstice are determined.
Relative height of the visible horizon line toward the true horizon plane is measured in these zones by the Theo 010 theodolite, and it is in the region of 1÷4grad. Angular dimensions of the summer, winter and vernal � autumn notches on the east wall of the North � East ground are between 30' and 3°. They are measured from the most probable locations of observation. The astronomical azimuths of the main foresights are also measured. The summer one is 56°16.6', and the winter one is 122°37.4'.
The defining of the points for astronomical observations within the frames of the monument's general borders shows that the most suitable location for this happens to be the western part of the north-east ground. This is a rocky bulge resulting after treatment of the rocky relief, convenient for observations of the east part of the celestial sphere. For observer, staying on it, the east horizon line is hidden and the sunrises can be observed through the notches at a height not grater than 3grad.
This allows us to fix comparatively easily the main Sun's azimuths in its extreme points during solstice and equinox. Also, an easily notable fact is that the profile of the east peripheral part of the ground has suitable for sight equipment relief forms (several cut into the rock notches). All this, together with the main axis's orientation of the semicircular rocky grooves (N-S), and the artifacts found from other researchers of this site, allows one to formulate the following archaeoastronomical hypothesis (Muglova and Stoev, 1996).
Autochthonous relief structure of the Harman kaya rock-cut megacomplex was used during the Eneolithic Age for position astronomical observation of the equinox and solstitial Sun, by the methods of the so called vector � horizontal astronomy.
Calculation of the basic astronomical azimuths is made by using the following formula:
where A is the geodetic azimuth, δ is the Sun declination, h � height of the Sun above the true horizon at the moment of rise, and φ is the geographic latitude at the place of observation (Nikolov, Kalinkov, 1998).
Sun declination at solstice is equal to the slope of the ecliptic towards the celestial equator. Today it is ε = 23.44°. In ancient times it was a little bit greater (Table 1). Determining astronomical azimuths, corrections for the refraction R in the zone of the horizon (R = 0.6° for the true horizon line), for the Sun disk diameter d (d ≈ 30') and for the curvature of earth's surface (0,0045° at every linear kilometer) have to be made.
|Slope of the ecliptic - ε||24.11°||24.07°||24.03°||23.98°||23.93°||23.87°||23.81°|
Method, worked out by Lockyer (1907) is used for determining the chronological boundaries of Harman kaya megacomplex use. The method includes measurements of the declination and height (necessary for calculating the azimuth), which the Sun would have at rise fixed by the summer or winter sight (notches on the east wall of the north-east ground), and seeking for such an azimuth in the archaic epochs. It should be taken into account that we register the upper part of the solar disc. Thus, the archaeological monument is dated by astronomical data.
Values of the azimuth, measured for the summer and winter sight (56°16',6 and 122°37',4) correspond to the values for 2000 B.C. (56°30' and 122°06'). The error of 30 arc minutes is admissible for visual observations (Stoev et al., 1999).
From the measured azimuths, geographical latitude of the site, and height of the Sun above the true horizon we determine the Sun�s declination by the formula:
We compare this declination with the slope of the ecliptic values e for the prehistoric epoch (Table 1). We can therefore draw the conclusion that the monument did function in the Eneolithic Age. Summer and winter solstice determining gives the possibility of measuring time periods within the frames of the Tropical year (1 year = 365.2422 days). Equinox is between the two solstices. The notch for its observing is between the notches for summer and winter solstice observation. Thus, people had another mark on the rock and could divide the summer-winter solstice time interval into two parts. These periods namely are connected with the seasons change. In that epoch they were structured as follows:
|winter solstice – vernal equinox||– 89 twenty-four hours|
|vernal equinox – summer solstice||– 93 twenty-four hours|
|summer solstice – autumn equinox||– 93 twenty-four hours|
|autumn equinox – winter solstice||– 90 twenty-four hours|
|generally||– 365 twenty-four hours.|
Measuring these comparatively uniform time spans gives the opportunity to compose a calendar structure allowing measuring the duration of one tropical year.
Our research shows that part of the autochthonic relief structure of the site was used for positional astronomical observations of the solar solstices by the method of vector � horizontal astronomy. Measurements show that Sun observations from the north-east artificially leveled ground were conducted in the period around 2000 B.C. There is a reason to suppose that these observations were included in the ritual practices of that time. Then the cult of God-Sun was widely spread and all the religious rites around the sacred rock probably were awared as cosmostructuring: actions overcoming the chaos and ensuring fruitfulness.
Authors: Alexey Stoev,Penka Muglova.
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