10/04/2026
Nine metres beneath the ground, workers encountered the remains of a forest that had vanished tens of thousands of years earlier.
In February 2019, excavation for a geothermal power station at Ngāwhā in New Zealand’s Northland region exposed an immense preserved kauri trunk.
It weighed approximately 60 tonnes and measured 16 metres—more than 52 feet—long. Its trunk was over 2.5 metres wide, and even parts of its bark remained attached.
The wood had survived because it was sealed beneath sediment in conditions that dramatically slowed decomposition. Radiocarbon analysis revealed something even more extraordinary.
The kauri had lived for approximately 1,700 years between about 42,500 and 41,000 years ago—spanning the Laschamps Excursion, when Earth’s magnetic field weakened severely and briefly reversed direction.
As the magnetic shield declined, more cosmic radiation reached the upper atmosphere, increasing the production of radioactive carbon-14.
The living tree absorbed that carbon. Each new growth ring preserved part of the changing atmospheric signal within its wood.
In 2021, researchers combined this kauri with samples from several other ancient New Zealand trees to construct a finely dated record of the magnetic event.
Climate models used in the study suggested that the weakened field, combined with periods of unstable solar activity, may have affected atmospheric ozone, circulation and regional climate patterns.
The researchers also proposed possible connections with megafaunal extinctions, changes in human behaviour and the disappearance of Neanderthal populations.
But those dramatic connections remain disputed. Other scientists argue that the archaeological, genetic and paleontological evidence does not prove that the magnetic event caused these extinctions.
The kauri did not preserve unquestionable evidence of a global apocalypse.
It preserved something more scientifically valuable, a timeline against which the claims can be tested.
