All maars formed in one complex eruption sequence which in the case of Devil Mountain Maar probably lasted only a few weeks to months. During the eruption, numerous individual explosions and surges took place and emplaced base surges and Strombolian deposits, while frozen blocks of sediment were ejected from the vents. Devil Mountain Maar appears to have formed from the coalescence of several vents during the course of the eruption. Individual explosive events formed the depressions on the floor of the maars.