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 of the Constitution, but the framers did not use the word "dormant". On September 15, 1787, the Framers of the Constitution debated in Philadelphia whether to guarantee states the ability to lay duties of tonnage without Congressional interference so that the states could finance the clearing of harbors and the building of lighthouses. James Madison believed that the mere existence of the Commerce Clause would bar states from imposing any duty of tonnage: "He was more and more convinced that the regulation of Commerce was in its nature indivisible and ought to be wholly under one authority." Roger Sherman disagreed: