The collapse of the vast mountain belt in the greater Rodopi area started approximately 40 million years ago; at that time, volcanic activity started to develop. Volcanic centers are spread on a 2,000 km long zone with an East-West

axis extending beyond E. Macedonia and Thrace to the Central and Eastern Rodopi (Bulgaria, FYROM, Serbia) as well as to a part of European Turkey.

Volcanic activity on the Hellenic territory is responsible for creating the Zarkadenia, Dipotama, Kalotyxo, Kirki – Aisymi and Feres – Dadia volcanic fields. Samothraki is on the border separating the volcanoes of E. Macedonia – Thrace and those in the Northern Aegean Sea; it houses products from both periods. As concerns the Eastern Macedonia and Thrace continental area, dating of volcanic products by radioisotopes yields ages between 35 to 23.6 Ma; the ages recorded in Samothraki reach up to 19 Ma.

A series of granite rocks are evident in the same Eastern Macedonia and Thrace region (plutonic bodies, volcano roots). Their age, placement and composition render them closely related to volcanites.