There is no single standard definition for a volcano. It can be defined from individual vents, volcanic edifices or volcanic fields. Interior of ancient volcanoes may have been eroded, creating a new subsurface magma chamber as a separate volcano. Many contemporary volcanoes rise as young parasitic cones from flank vents or at a central crater. Some volcanoes are grouped into one volcano name, for instance, the Mount Edziza volcanic complex, although individual vents are named by local people. The status of a volcano, either active, dormant or extinct, cannot be defined precisely. An indication of a volcano is determined by either its historical records, potassium-argon dating, radiocarbon dating, or geothermal activities.