Rhyolitic lavas of Argos (17,18)

They appear on the southern rim of the caldera and comprise the southern slopes of the volcano. They are perlitic domes and lava flows of rhyolitic composition. 

Wherever the foot of flows is visible, severe auto-brecciated effects are evident, while series of block and ash flows also appear (formation no. 17) from monolithiologic breccias, resulting from the partial collapse of domes or of thick lava flow fronts originating from the same volcanic activity.

The foot of the formation on the southern slopes of the caldera is quite remarkable; –auto-brecciated rhyolitic lava is deposited on mud flows from the underlying middle volcaniclastic rocks.

Only perlitic – obsidian block and ash flows occur on the SE cliffs of the caldera.

Their thickness is up to 80m and their color varies from light ash black, depending on the magma cooling speed.