Ancient Northland swamp kauri solves 42,000 year old mystery 21 Feb, 2021 05:00 PM 7 minutes to read Some of this giant ancient swamp kauri tree uncovered at Ngāwhā has been used by researchers to confirm the date when the Earth reversed its magnetic poles. Photo / Peter de Graaf Northern Advocate Ancient swamp kauri from Northland has been used to confirm a temporary breakdown of Earth's magnetic field 42,000 years ago sparked major climate shifts leading to global environmental change and mass extinctions. A new international study using ancient swamp kauri from Ngāwhā shows this dramatic turning point in Earth's history was triggered by a reversal of Earth's magnetic poles and changing solar winds.