Volcano of classifying magmatic volcanoes is by their frequency of eruption, with those that erupt regularly called active, those that have erupted in historical times but are now quiet called dormant or inactive, and those that have not erupted in historical times called extinct. However, these popular classifications—extinct in particular—are practically meaningless to scientists. They use classifications which refer to a particular volcano's formative and eruptive processes and resulting shapes. There is no consensus among volcanologists on how to define an "active" volcano. The lifespan of a volcano can vary from months to several million years, making such a distinction sometimes
Dormant Commerce Clause Marsh Company to place a dam across the creek, can, under all the circumstances of the case, be considered as repugnant to the power to regulate commerce in its dormant state, or as being in conflict with any law passed on the subject." If Marshall was suggesting that the power over interstate commerce is an exclusive federal power, the Dormant Commerce Clause doctrine eventually developed very differently: it treats regulation that does not discriminate against or unduly burden interstate commerce as a concurrent power, rather than an exclusive federal power, and it treats regulation that does so as an exclusive