Ancient Tree shows geomagnetic field reversal?

Mar 2019
Ancient tree with record of Earth's magnetic field reversal in its rings discovered

Claims discovery of NZ kauri tree dated as living for 1,500 years between 41,000 to 42,500 years ago.
Although obviously interesting a far more comprehensive method was found sometime ago to track magnetic shift. When lava solidifies the crystals align with the Earths magnetic field. So by dissecting lava flows we can (In some cases) track magnetic movements almost on a day by day basis.