During the early stages of the Composite Stratovolcano cycles, a series of eruptive events took place that marked the transition from the earliest shield volcano to stratovolcano.
This period of transition is dominated by three dominant lava flows derived from northern and eastern central eruptive centers. These flows form the upper parts of the caldera walls in the northern, northeastern and eastern segments and cover the north–western slopes down from the Monastery of Evagelistria and the eastern slopes between the areas of Linevrochia and Kremasto. The first, a 40 m thick andesitic lava flow, was emitted from a main central vent, since it appeared all around the upper caldera walls with the exception in the southwest, where the young Profitis Ilias rhyodacitic lava flows probably cover it. An andesitic neck and a small scoria cone in the upper eastern slopes close to the present day caldera rim represent two additional satellite eruptive centers, all within the same geological unit.
