City of VARNA and the region – THE STONE FOREST
April 3rd, 2008
The Stone Forest is a fabulous natural phenomena most known with its Bulgarian name “Pobitite Kamani”, which means “stones beaten into the ground”, a name completely corresponding to the reality. These are numerous limestone pillars as high as 10 m, hollow or solid cylinders, truncated cones, different bulgings and single rocks and cliffs.
Nowadays is believed that these carbonate-cemented sandstone structures were formed due to microbial methane oxidation around natural gas seepages - so called “bubbling reefs”. The cementation occurred in the subbottom marine sands some 50 million years ago and now are exposed by subsecuent erosion of the surrounding unconsolidated sediments and vertical tectonic movements of the earth crust.
The spectacular landscape of “Pobitite Kamani” is spotty spread in a North - South orientated belt about 3 km wide and 8 km long. The stones are clustered in seven large groups and several separate small areas embracing a total area of more than 7 square kilometers. They are localized running from south of Beloslav town, northward of lakeroad and railway, around the Strashimirovo village and fertilizer plant crossing the road E70 and highway finished around Slunchevo and Banovo villages.
The poles have been known as a sacred place for centuries but are documented for the first time in 1829 and since then it has been of interest to many scientists. This unique place is announced as a national natural landmark in 1938 and now it is lobbing to be included in the UNESCO World List of Geological Forms.
The structures of “Pobitite Kamani” consist of carbonate - cemented sand and silt deposits of Lower Eocene age, the same sediments in which they occur. Except the exposed on the earth surface forms they are developed in another one to three underground levels more. The forms of any level usually grow upon a solid limestone substratum most probably with the same origin.
For centuries the nature was shaping the stones, to turn them into awful sculptural creation - animals, peoples, monsters, mythical creatures. “The Stone Guardians”, “The Camel”, “The Throne”, “The Stone Forest”, “The Big Falos” are the names of some of these natural phenomenas.
Тhe main, “Dikilitash” group is the most impressive and in a best state of preservation. It comprises of 300 big and small pillars in a large stripe (about 850×120 m) and over 50 in a smaller spot southward. Some of them are broken into two or three segments, other lie down, looking as if being excavated from their roots. The “Strashimirovo” group is also very spectacular. It is situated southwards of the main group and is composed of four rows from north to south. A characteristic feature of the pillars here is that the middle part of any level is bulging like two communicating truncated cones. The circumstance of some bulgings is over 9 m. The”Slunchevo” and “Banovo” groups located in the vicinity of the corresponding village are charming too. A pillar resembles a frozen fountain; another with base of 12 m in circumstance is a rock lion; others are colossal awesome mushrooms. The “Karierata” group includes several natural and man-made outcrops which are the most instructive for development of these unique carbonate structures. They attract the attention of scientists from the beginning of the 1970s when this area was an active sand-pit, abandoned now. All four levels of the pillar development with a diversity of forms can be observed here as well as limestone layers at their bases and all these in a wall over 25 m high. Other groups are situated south of Beloslav town and also deserved to be seen, that’s why I recommend to whom is already convinced to visit this unique place to reserve one whole day for the trip prepared to walk 15-20 km, have available food and take 30-40 snapshots at least.
Several basic hypotheses about the genesis of the phenomena have been developed ranging from designing of the structures by mechanical acting of the environmental factors (wind, rain, sea waves) to the precipitation of carbonate from percolating groundwaters (stalactite mode of formation) to coral complexes, algal bioconstructed build-ups (bioherms) and lithified forest. The answer comes from the gas seepages, which were recently found in the Kattegat area, offshore Denmark where the modern submarine landscape “the bubbling reefs” is and it is very similar to the “Pobitite Kamani”.
Natural gas seepages are known from many places all over the World, both on land and offshore. They occur where suitable pathways have been developed from the gas source (source rocks, deep sited gas fields or shallow gas-charged sediments) to the surface (seafloor or the ground). Once a gas migration path is established a methane oxidation begins inducing precipitation of carbonate (so called “methane derived carbonate”) which litifies the sediment along the gas channel. Cementation of the sediment goes on around the methane pathway, fills the channel and the pillar structure grows from the outside. A similar process may occur laterally forming a substratum layer. Exposure of the carbonate - cemented sandstone structures on the seafloor happens, as a result of submarine and earth surface erosion of surrounding unconsolidated sediments due to sea level droppings (regressions) and risings (transgressions). After many, many years with the help of vertical tectonic movements of the earth crust, the result of these processes is now exhibited, to make us admire these miraculous sculptures. However, the recently obtained scientific results suggest that carbonate formation in the area of “Pobitite Kamani” may have more complex origin and continues today by precipitation of carbonates from meteoric groundwater.
The above two images show very similar landscapes. The left one is a picture taken from the main, “Dikilitash” group of the “Pobitite Kamani” area, near Varna, Bulgaria and the second one is an art expression of the modern submarine landscape “the bubbling reefs” in the Kattegata area of active gas seepages offshore Denmark.
