One of the most impressive volcanic edifices of Lesvos is the volcanic edifice (dome) located in Mithymna.
The castle and settlement of Mithymna were built on the volcanic edifice formed by rising magma in the last phase of the volcanic activity of Lesbos, 16.5 million years ago.Its creation is associated with rising magma that moved at low speed, penetrated the older metamorphic rocks of the bedrock, obscured the older layers of pyroclastic formations that covered the area, and created a giant dome without causing a volcanic eruption.
The magma cooled and solidified at a relatively shallow depth. The erosion of the pyroclastic rocks that once surrounded it has revealed the impressive dome.