Are these stone pillars in Bulgaria the remnants of ancient, bubbling hydrocarbon reefs?

Countries & Cities · Published 30 September 2026 Swipe more like this →

In short: Pobiti Kamani, or planted stones, is a desert-like landscape in Bulgaria filled with hundreds of hollow, tubular rock pillars. Long a geological mystery, these structures were once attributed to coral or simple weathering. Today, evidence suggests they are the fossilized pathways of ancient methane-bearing fluid plumes rising through sand.

Located on the border of the Varna Province, this unique site spans an area eight kilometers long and three kilometers wide. The phenomenon consists of seven distinct groups of stone pillars, with the primary group, Dikilitash, containing over 350 individual structures. Some areas, such as Strashimirovo, are noted for pillars with distinctively bulging middle segments. First described by Russian archaeologist Victor Teplyakov in 1829, the site was officially designated a natural landmark in the late 1930s to ensure its preservation.

The origin of these pillars has been debated for nearly two centuries. Early hypotheses were split between organic and abiotic theories. Some researchers proposed that coral activity created the shapes, though detailed investigations found no evidence of coral. Other theories pointed to desertification, prismatic weathering, or the formation of sand and limestone concretions. Modern geochemical analysis, however, has shifted the consensus toward a more complex mechanism involving paleo-hydrocarbon seeps. Studies, including work by De Boever et al. in 2009, suggest that microbial mediation of hydrocarbon oxidation led to carbonate precipitation around rising fluid plumes, effectively cementing the surrounding sand into the columns seen today.

This theory is supported by petrographic and stable isotope geochemical data, which show that the low magnesium calcite cements within the pillars are strongly depleted in the heavy carbon isotope 13C. These columns were originally buried in sand; their current desert-like appearance is the result of recent sand removal. The site remains a subject of scientific interest, serving as an exceptional record of ancient fluid migration. Beyond its geological significance, the site has occasionally entered the public consciousness in strange ways, such as in 2020 when a photoshopped image of the pillars was falsely circulated on social media as a NASA photograph of Mars.

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