How was Rangitoto Formed?

Rangitoto was formed by a series of eruptions between 600-700 years ago.
The volcanois not exspected to become active agian.
The eruption first began below water level in the Hauraki Gulf and over several months the island slowly became visible above the sea level. The eruptions lasted for about 12 months.
Of all of Auckland's volcanoes, Rangitoto Island is the youngest and also the largest of the total of 48.