A construction site for a new Auckland wastewater tunnel has uncovered some ancient natural history.
Workers at the site in Māngere have been digging up almost intact shells, which geologists have dated as being three to four million years old.
That makes them older than Auckland’s volcanoes.
Watercare’s programme director, Shayne Cunis, described the find as “once in a lifetime”.
“Very rarely will we ever dig to these depths again,” he told 1 NEWS.
The shells have been found while workers dig 50 metres into the ground, to put in a support wall for the $1.2 billion tunnel build.
They first came up in January, at around a depth of 30 metres, and were later sent to GNS scientists for dating.
Geologist Kyle Bland says the shells are “remarkably preserved”.
“Just pristine,” he says, “almost as if the things had only just been alive.”
That is in great contrast to other sites, where the shells have been mostly dissolved away.
Mr Bland says they would have existed in what was then “shallow” ocean waters – between 10 and 50 metres deep – and developed thick shells as a result of living in an environment with powerful waves.
“Because if an animal is going to invest all this energy in having a big, thick shell, then like a rugby player you’ve got to be big and strong to be able to handle the environment,” he says.
Once Covid-19 restrictions are lifted, GNS scientists will visit the site to see the find for themselves.
While many of the shells have been broken by the machinery digging into the ground, Mr Cunis expects to find plenty more of them as the excavation continues.
They are discussing what to do with the whole ones they have already dug up, with ideas including making them into an artwork to commemorate the find.
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