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Fossil leaves open window into Coromandel’s ancient climate - 21/02/2020

A rich treasure trove of information about Coromandel’s prehistoric vegetation and past climate has been uncovered near Whitianga.

Dorothy and Ian Meredith and Kath Garland discovered the fossils in the clay banks of their property, which were once layers of mud on the bottom of a lake.

The families were aware there were fossils hidden on their property and had often taken exchange students, children and grandchildren to look for them.

But it wasn’t until they saw a television programme on the Foulden Maar fossil site in Otago that they realised the fossils might be significant.


My current research focuses on climate reconstruction of the Miocene Epoch (23 to 5 million years ago) through the analysis of leaf fossils

Dr Liz Kennedy


The family approached Otago University geologist Daphne Lee, who realised their potential worth to scientific research.

Auckland palaeontologist Bruce Hayward and paleontologists from GNS Science were contacted and visited the property to sample some of the fossils for analysis.

Violent volcanic eruptions spewed ash and lava over the prehistoric Coromandel landscape, but there were also periods of calm when lakes were formed. On the lake floor, the layers of mud provided perfect conditions to preserve the leaves.

“My current research focuses on climate reconstruction of the Miocene Epoch (23 to 5 million years ago) through the analysis of leaf fossils.” Liz Kennedy from GNS Science says.

“We look at the size and shape of leaves of living plants and examine the correlation with climate – the range of temperatures and rainfall as the plants were growing. We use this information to reconstruct past land climates from fossil leaves”

Dr Kennedy says she would be delighted to hear from anyone in the Coromandel who has found fossilised leaves.

“The Miocene was a time when climate was warmer than present day, so these plants can tell us about the type of climate we might expect in coming centuries if we don’t reduce carbon emissions.”

This study is part of ongoing research by GNS scientists to use the local geological record to improve our understanding of the potential impacts of future climate change.

Phyllocladus leaf
Toatoa leaf

One of the significant finds was this Phyllocladus leaf, with its cones still attached (left). This rare find is a relative of our native celery pines, Toatoa (right). Totatoa image by Dr Lawrence Jensen, University of Auckland