Nisyros
Nisyros is one of the youngest large volcanic centres in Greece included in the active volcanoes along with Methana, Milos and Santorini.
The oldest rock formations are 160 000 years old, while the youngest (prehistoric) are 15 000 years old and cover the entire island. Most of Nisyros is mountainous, volcanic and very fertile. The island is composed of volcanic rock formations, with swelled elevations that were formed by previous volcanic activities.
The various rock formations, (basalt etc.) have been used for the construction of various buildings such as the Palaiokastro and the bell tower of the Church of Saint John the Theologian just outside Nikea. The base of the island has been formed by lava. The rocks are covered by pyroclastic deposits and volcanic mud. Two possible eruptions occurred several millennia ago, around 25 000 years back. A large depression occurred in the eastern part half way across the island. The western crown of this depression forms the highest peak of the island. The peak of Saint John is in the eastern part of the depression and is about 100m above sea level.
