Using Ancient Ovens to Trace the History of Earth’s Magnetic Field

Scientists have known for some time that the Earth’s magnetic field has undergone significant changes throughout the planet’s history. In fact, about once every few hundred thousand years, it completely reverses – what was once magnetic north is now magnetic south.[1. The planet’s magnetic poles are a small distance away from the geographic poles, which are defined based on the Earth’s rotation.]

There is a lot of evidence for this, the most convincing of which is the fact that if you dig down a bit, you find magnetized rocks all pointing in the same direction as each other – but that direction changes as you dig deeper, and those changes are consistent in rocks all over the planet.

Maori oven
A recreation of a Maori oven. Photo via Genuine Maori Cuisine.

Scientists are still trying to understand these phenomena, and they need more data showing exactly what the magnetic field has been up to.

Enter Dr. Gillian Turner, a physicist at Victoria University in Wellington. Edible Geography writes that Turner, along with an archaeologist, have made their own versions of old Maori ovens, like the one pictured above. They showed that these ovens could have heated rocks to high enough temperatures that they could have shifted their magnetic orientation to match the Earth’s field.

Read more at Edible Geography.