Tephra-layers occur in clusters and exhibit an episodic volcanism in the Eifel.
Strombolian, phreatomagmatic and evolved tephra are distinguishable.
Correlation of maar sediment cores by tephra layers is continuous to 220 ka b2k.
Phases of intense volcanism are correlated with climatic change.
14C dates and ice-core tuning provide precise ages of the youngest eruptions.