An ancient tree that contains a record of a reversal of Earth's magnetic field has been discovered in New Zealand. The tree -- an Agathis australis, better known as its MÇori name kauri -- was found in Ngawha, on New Zealand's North Island, during excavation work for the expansion of a geothermal power plant, stuff.nz reports. The tree, which had been buried in 26 feet of soil, measures eight feet in diameter and 65 feet in length. Carbon dating revealed it lived for 1,500 years, between 41,000 and 42,500 years ago... The lifespan of the kauri tree covers a point...