The formation of the Rockeskyller Kopf began, as in the case of the maars, with steam explosions, which piled up coarse-grained lapilli. Next came Strombolian eruptions, as the intermittent ejection of incandescent cinder is called. The hot cinders melted on impact to become scoria, which is easily confused with lava flows. In the final phase, lava streams were outpoured, whose remains may still be seen as lava sheets or pipe filling.