Feeds

Kiwi archaeologists cook up a record of Earth’s magnetism

What’s that in your hangi?

High performance access to file storage

A kind of oven used by the Maori since long before Europeans arrived in New Zealand is being mined for archaeological information about the history of Earth’s magnetic fields.

Scientists from Victoria University in Wellington, New Zealand, say that there’s a gap in the global palaeomagnetic record in the south-west Pacific, and hopes that by finding and examining ancient earth ovens – “hangi” in the indigenous Maori language – the record can be filled.

The hangi follows a form common in many societies: a hole in the ground is lined with hot stones and covered with the meat to be cooked (on a wooden rack), with damp material such as fern fronds providing water to steam the meat.

Dr Gillian Turner, who is leading the work, explained to the BBC that stones used in the earth ovens could have been heated enough that magnetic particles in the stones would re-align to the Earth’s magnetic field.

Thermocouples placed in an experimental hangi showed the temperatures among the rocks reach around 1,100°C.

That’s hot enough that some rocks – specifically andesite boulders, which are a hangi favourite because they don’t shatter in the heat – re-magnetise. The rocks pass their Curie temperature, and as they cool, their magnetic fields will be aligned to Earth’s.

Hence by measuring the magnetism in abandoned pits, Dr Turner hopes to reconstruct records going back between 500 and 700 years, when the Maori first arrived. Charcoal in the ovens will be used to carbon-date the sites.

Older magnetic information can be reconstructed from sources such as volcanic rocks and lake sediments – a good thing, since Dr Turner hopes to fill in a magnetic record over about 10,000 years. ®

High performance access to file storage

More from The Register

next story
Elon Musk's LEAKY THRUSTER gas stalls Space Station supply run
Helium seeps from Falcon 9 first stage, delays new legs for NASA robonaut
Solar-powered aircraft unveiled for round-the-world flight
It's going to be a slow and sleepy flight for the pilots
Russian deputy PM: 'We are coming to the Moon FOREVER'
Plans to annex Earth's satellite with permanent base by 2030
LOHAN's Punch and Judy show relaunches Thursday
Weather looking good for second pop at test flights
Saturn spotted spawning new FEMTO-MOON
Icy 'Peggy' looks to be leaving the outer rings
Discovery time for 200m WONDER MATERIALS shaved from 4 MILLENNIA... to 4 years
Alloy, Alloy: Boffins in speed-classification breakthrough
India's GPS alternative launches second satellite
Closed satnav system due to have all seven birds aloft by 2016
Curiosity finds not-very-Australian-shaped rock on Mars
File under 'messianic pastries' and move on, people
Top Secret US payload launched into space successfully
Clandestine NRO spacecraft sets off on its unknown mission
prev story

Whitepapers

Mainstay ROI - Does application security pay?
In this whitepaper learn how you and your enterprise might benefit from better software security.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Mobile application security study
Download this report to see the alarming realities regarding the sheer number of applications vulnerable to attack, as well as the most common and easily addressable vulnerability errors.