Cave of the Fossil Tree Trunks
The Cave of the Fossil Tree Trunks, located along the loop of the cliff near the access to the Archaeological and Environmental Park (PAAO) near Piazza Cahen (go on to porta Soliana, than turn right on the way to Cannicella), is a very interesting artificial cave, hosting paleobotanical remains dating back to 350 thousand years ago, belonging to the ecosystem that existed well before human presence, and preceded the formation of the tufa rock cliff on which Orvieto rises.
Inside some of the caves opening up along the sides of the tufa rock cliff, other cylindrical holes can be seen, either in a vertical position, or slightly oblique, that can be completely empty or filled with a dark coal-resembling material which feels oily to the touch: these are what is left of those trees that formed a thick forest where the cliff currently rises. Their presence tells us that before the eruptions of the Volsini Mountain system, the environment was very different from the one we are familiar with: from the Pliocene sea, the presence of which is confirmed by the large number of fossils found in the clays located at the feet of the Cliff, the area turned into an environment rich in surface water resources, rivers and lakes, with quite extensive forests. The trees that can be seen in this cave were covered by volcanic materials (approximately 320 thousand years ago) that provoked their slow carbonization, so they could keep their shape and can still be perfectly recognized. They can be seen in life position as the volcanic eruptions that covered them were not violent enough to provoke their complete destruction. Looking carefully, event he growth rings of some trees can be spotted, while other trees left the imprint of their bark in the tufa rock and this can be perfectly identified.
Such trees were found following the excavations carried out to procure pozzolana that could be used as a construction material. Those who conducted the excavations came across these remains and possibly did not realize what they were. Therefore part of the trunks were taken away, the rest remaining embedded in the rock. The water that percolated through the tufa rock eroded the coal and removed it, and that is why some of the cylindrical holes are empty. Those trees were possibly species of Conifers for the most part, but in-depth research on this matter has yet to be carried out. But they are definitely extremely important testimonies of the history of Orvieto’s territory.