What began as an infrastructure project, is now also a project to uncover who inhabited Auckland’s seas and forests 3.5 million years ago.

We’ve partnered with Watercare’s Central Interceptor project and are in conversation with the Mana Whenua Kaitiaki Managers Forum, to collect, identify, care for and research fossils recently discovered during the excavation of the Central Interceptor main shaft at Greenwood Road, Māngere.

Check back on this page for regular updates and exciting new developments.

A project for the history books...

A project for the history books...

The $1.2b Central Interceptor is a giant underground wastewater tunnel running 14.7 kilometres from Māngere Wastewater Plant Treatment to Grey Lynn.

Older parts of Auckland, have a combined water and stormwater network. In wet weather, the system is engulfed by rain and overflows occur into neighbouring waterways. The Central Interceptor will store as well as convey flows to the treatment plant for processing. The tunnel will enable other projects, such as a replacement Western Interceptor to take place. Once finished, they will prevent around 80 percent of wet weather overflows to inner city beaches and waterways and see significant improvements to water quality in the Manukau Harbour and Hauraki Gulf.

The fossils were found during the early phase of construction when a hydrofraise machine was excavating the main launch shaft for Hiwa-i-te-Rangi, the Tunnel Boring Machine, which is digging the Central Interceptor tunnel. The material was discovered in a five-metre-thick shell layer in the geological Kaawa formation some 35 metres below ground.

The image on the right shows the super-sized Central Interceptor tunnel being built. Construction is due to finish early 2026.

...and natural history for our collection

...and natural history for our collection

Although the bulk of the sediment discovered consists of sand and crushed shell fragments, the layer has yielded more than 200 different species of molluscs and other fossils to date, many of which are in very good condition. Most importantly, a number of these species are new, previously unknown to science, including two fossil flax snail species.

The Ghella Abergeldie Joint Venture (GAJV)*/Watercare partnership have agreed that any unique or important material unearthed during the excavation of the Central Interceptor shaft will be lodged with Auckland Museum where, in Phase One of this project, the Museum will collect, identify and accession the Māngere Kaawa Formation fossils into the collection.

The Maoricardium spatiosum, a giant extinct cockle, from 3-4 million years ago. The large cockle measures 17cm wide, with a height of 15cm. It has a depth of 8cm. AWMM MA126260.

Similar molluscan fossils were recovered in the 1940s from a well sunk by the then-Waitemata Brewery at their site at Ōtāhuhu. Its manager, Mr Morton Coutts, contacted scientists to evaluate the spoil heaps and consequently fossil specimens representing at least 60 new species were lodged with Auckland Museum, Auckland University and the New Zealand Geological Survey (now GNS Science).

The number of fossil species found in the sediments excavated at Māngere exceeds the number found at Ōtāhuhu. To date, they appear to be more complete and better preserved. The spoil continues to yield new species and the Māngere material therefore presents a unique opportunity to shed further light on the story of Auckland’s geological history. It will substantially enhance knowledge of the fauna that inhabited the region’s seas and forests 3.5 million years ago.

Shown here is the Maoricrypta profunda, slipper limpet. The specimens represent a growth series and show the variation in the species from relatively juvenile to adult. The largest Maoricrypta measures: width 4cm, height 5cm and depth 1.5cm. AWMM MA12605.



Auckland Museum project technicians Nathan Collins and Thomas Stolberger have been working hard at processing and archiving the fossil taonga collected from the Central Interceptor construction site in 2021. These specimens have now been divided into subsets for the Auckland Museum palaeontology collection, local mana whenua, and educational outreach.

Working together with palaeontologists from around Aotearoa, the pair have helped to identify over 250 different fossil taxa, including several undescribed species that are new to science. These new species will be described and named by palaeontologists in a future scientific article. A report on the progress and preliminary findings of the project is nearing completion and will be published in 2023.

Māngere Kaawa Formation fossils in the media

Big, bigger, biggest

Big, bigger, biggest

From the size of the machinery to the quantity and quality of fossils that were unearthed, almost everything about this story is over-sized.

In this blog, Wilma Blom (Curator, Marine Invertebrates) details Watercare's ground-breaking Central Interceptor Project and some of the significant specimens it uncovered.

Image: Watercare Central Interceptor Executive Programme Director Shayne Cunis holding two of the specimens in May, 2020. Photo Courtesy of Watercare. 

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