Middle volcaniclastic rocks of Nisyros (19)

These appear almost over the entire extent of the caldera cliffs, as well as on the NW slopes of the volcano. These relate to three main explosive activity events, interposed between the lava flows of the Middle andesitic lavas.

Occurrences at the NW side are layers comprising lapilli and small blocks of fallout scoriae, ash-colored at the base and red at the top.

The same layer at the NE and SW cliffs of the caldera, comprises gray-colored ash and blocks from fallout and surge deposits; it is approximately 10 m thick, and has been altered by hydrothermal activity.

Impact sags from volcanic bombs as well as structures of soft sediment intrusion and entrapping from the deposited tuffs of the superimposed middle andesitic flows are spectacularly shown on road cuts as it crosses the caldera cliffs. Deposits in the area under the Stavros monastery (southern slopes of the caldera) are mainly mud flows and debris flows.

they are 5-15m thick.