Hangi stones lead to collaboration between Maori culture and science

A study to investigate the use of hangi stones, lava and sediment records could be used to map changes in the Earth’s magnetic field.

Victoria University of Wellington geophysicist Gillian Turner is measuring the magnetisation of hangi stones as part of a project to determine the geomagnetic field of the southwest Pacific over the past 10,000 years.
Victoria University of Wellington geophysicist Gillian Turner is measuring the magnetisation of hangi stones as part of a project to determine the geomagnetic field of the southwest Pacific over the past 10,000 years.

Dr Gillian Turner from the School of Chemical and Physical Sciences has received Marsden funding to map changes in the Earth’s magnetic field in the Southwest Pacific region as far back as 10,000 years. Currently, records only date back to the past 100 years in this area. Stones that have been heated up are remagnetised to the current magnetic field once they cool. New Zealand has Māori hangi pits that have been dated as 600-700 years old which could be used as a record of past magnetic fields. Dr Turner and archaeologist Dr Bruce McFadgen visited 12 historic hangi pits in various locations around New Zealand including: Hawke’s Bay, Mount Taranaki, Mount Ngauruhoe, Otaki, Wellington and Nelson.

The hangi was organised by Victoria University of Wellington’s Te Kawa a Māui/School of Māori Studies and coincided with the Māori New Year, Matariki. The hangi held at Waiwhetu Marae proved to be popular attracting hundreds of visitors. The hangi was started at dawn and only took a few hours before the stones reached temperatures of 1000 degrees. The stones then took three days to cool down before they could be transported back to the laboratory with the permission of their owners.

This Marsden funded research will take three years to complete and will enable scientists to understand past changes in the Earth’s magnetic field and enable them to predict future changes. The research will also be able to create a method that will allow additional archaeological hangi sites to be dated. Gillian notes it was a privilege to work with Māori in this experiment. An interview with Dr Bruce McFadgen and Dr Gillian Turner at start of this project, listen to the interview on the Radio New Zealand website. (start time 34:47-56.02):