The petrification was caused by rapid burial in volcanic ash, which prevented decay and allowed for mineral substitution of plant cell structures.
The fossilized trees belong to the taxodiaceae family, similar to modern redwoods, and indicate a subtropical climate 20 million years ago.
Some of the trunks in this specific site remain in their original growth position, including intact root systems.
The forest was destroyed by violent volcanic eruptions from local centers that deposited thick layers of pyroclastic material over the vegetation.
This site is part of a larger network of protected fossil parks across western Lesvos, which together form a UNESCO Global Geopark.
The Bali Alonia Park is a designated outdoor exhibition area of the Natural History Museum of the Lesvos Petrified Forest, located in the village of Sigri. It preserves in-situ fossilized tree trunks dating back approximately 17 to 20 million years, formed during intense volcanic activity in the Aegean. The park features a walking trail that allows visitors to observe upright and prostrate trunks, some exceeding several meters in length, preserved in volcanic ash and pyroclastic material. The petrifaction process occurred when silica-rich hydrothermal fluids replaced the organic tissue of the trees. The site highlights the geological evolution of the Aegean Basin and the subtropical climate that once characterized this region. It is one of the most significant paleobotanical sites in Europe due to the high density of well-preserved fossilized root systems. The park is integrated into the Lesvos Island UNESCO Global Geopark network.
The elevated viewing point along the path providing a panoramic frame of the largest upright fossilized trunk against the backdrop of the Sigri valley.
Bring a hat and high-SPF sunscreen as the site is an open, exposed volcanic slope with very little natural shade.
Wear sturdy, closed-toe hiking shoes as the terrain is rugged, uneven, and contains loose volcanic scree.
Carry at least one liter of water, as there are no refreshment facilities within the park boundaries.
Do not visit during the heat of midday in July or August, as the volcanic soil reflects significant heat and there is minimal shade.
The park typically follows seasonal operating schedules aligned with the main museum, often closing during the winter months.
Do not touch, climb on, or attempt to remove any fossilized material; stay strictly on marked paths to prevent erosion.
