It mainly appears on the northern slopes of the volcano, where the entire formation is developed. Minor occurrences are on the SW slopes, on top of the Nikia lavas. A minor occurrence pumice deposits is located in the Lefkos bay, underneath post-caldera lava flows.

These are white rhyolitic pumice clasts, deposited through a plinian eruption by fallout, surge and flow mechanisms (Limburg & Varekamp, 1991).

The base of the formation comprises a coarse bed of fallout pumice, lapilli and blocks (15-20cm average diameter) with low percentage of ash; maximum thickness is 8m and is slightly layered to massive.

Thickness values of up to 40m are observed in the pumice quarry, SW of Pali; they are the result of a paleovalley being filled by pumice that slides in there, following its initial fallout on the steep slopes The upper members of the formation comprise of highly fragmented magma which is deposited through surge and flow mechanisms.

This part of the formation is characterized by crossbedding, dunes and antidunes, pumice lapilli severely rounded during the flow process, massive ash flow layers. A concentration of xenolith lapilli and block layers (up to 95%) is observed in the higher flow units.

These come from the deep geothermal reservoir (skarn and hydrothermally altered volcanics) drilled by borehole NIS-1 (Geotermica It., 1983). These are lag breccias layers and lenses deposited by pyroclastic flows. Flow and surge deposit layers mainly occur in the N – NE part of the volcano’s slopes. Their depositional mechanism control their distribution and thickness by the local topography.

Their maximum thickness reaches 60m, in a paleovalley with NE direction, south of cape Katsouni. The last pyroclastic layers of the eruption comprise highly fragmented grey perlitic ash with very low vesiculation.

This demonstrates the decisive role of the geothermic fluids in the last explosive phase of the eruption.

In addition to rhyolitic pumice clasts, clasts of andesite magma of dictitaxitic texture are also observed (4-5%).

The vent of the eruption is estimated to be close to Emporio, as this area exhibits the maximum thickness values of the fallout layer and the maximum diameters of pumice blocks.