The volcanic activity in the Vogelsberg, as well as that of the North Hessian Volcanic Region to the north which extends as far as Adelebsen in Lower Saxony, is connected with fault block activity that, during the Tertiary, led to the formation of the Lower Hessian Basin. It began in North Hesse about 20 million years ago during the lower Miocene, reached a peak about 13-12 million years ago and came to an end about 7 million years ago, during the upper Miocene. The volcanism of the Vogelsberg was mainly active during the Middle Miocene, according to potassium-argon dating 18.5-10 million years ago, reaching its peak 17-15 million years ago.