The 140 sq km Auckland volcanic field, which is a late Pleistocene to late Holocene in age, lies at the southern end of the Northland Peninsula and is overlain by New Zealand's largest city. More than 50 maars, tuff rings, small lava shields, and scoria cones have formed in the past 140,000 years in an elliptical volcanic field 29 km long in its largest (N-S) direction. The Auckland volcanic field has dominantly produced intraplate alkali basaltic to basantic rocks forming the northernmost of a group of Quaternary volcanic fields of the Auckland Intraplate Province. Of the 19 eruptions known to have occurred within the past 20,000 years, only one eruptive center is known to have been active during the Holocene (Smith and Allen, 1993). The Rangitoto eruption, about 600 years ago, was the largest of the Auckland volcanic field and created the 6-km-wide Rangitoto Island, which consists of multiple scoria cones up to 260-m high that cap a low shield volcano with a broad apron of lava flows.