Pobiti Kamani: The Stone Forest, Bulgaria

About 18 km to the west of Varna, Bulgaria, on the road to the capital of Sofia is a remarkable natural area called Pobiti Kamani or the Stone Forest. At first glance, it looks like the ruins of an ancient temple, but these broken stone pillars are all natural.

The stone columns are distributed in small groups across an 8 km long belt along the northern Bulgarian Black Sea coast. They vary in height with some reaching 5 to 7 meters tall, and thickness ranging from 30 centimeters to 3 meters across. The most curious thing about these pillars is that they are mostly hollow and filled with sand. They don’t have a solid foundation or attached to the bedrock. Instead, they are loosely stuck into the surrounding sand as if some one had hammered them into the earth.

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Photo credit: Diego Delso/Wikimedia

The stones have been known since the ancient times but were first documented by the scientific community in 1828. Since then, dozens of theories have attempted to explain their formation, ranging from coral growth to Eocene bubbling reefs, to limestone concretions.

One of the most plausible explanation comes from the Bulgarian geologists brothers Peter and Stefan Bonchev Gochev. The brothers believe that the columns date back to the Cenozoic Era, about 50 million years ago, when much of Eastern Europe was covered by oceans. Sediments and sludge settled to the bottom of the seabed, and were compressed into limestone. Some time later methane gases from ancient deposits started seeping from the sea bed. As the pressurized gases made their way up through the limestone layer, they left behind long tubes. Millions of years later after the sea receded away, erosion of the limestone layer left the tall columns stuck into the ground. The gas-seepage theory doesn’t explain everything, but it’s the best we have.

Pobiti Kamani was designated a natural landmark in the late 1930s. It was nominated for the UNESCO World Heritage Site status in 2011, but hasn’t been able to make the cut.

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