Volcanic eruptions eject large amounts of carbon into the air. The carbon is of geological origin and has no detectable 14C, so the 14C/12C ratio in the vicinity of the volcano is depressed relative to surrounding areas. Dormant volcanoes can also emit aged carbon. Plants that photosynthesize this carbon also have lower 14C/12C ratios: for example, plants in the neighbourhood of the Furnas caldera in the Azores were found to have apparent ages that ranged from 250 years to 3320 years.