It occurred between 42,200 and 41,500 years ago, during the end of the Last Glacial Period.
It was discovered from geomagnetic anomalies found in the Laschamps and Olby lava flows near Clermont-Ferrand, France in the 1960s.
[3] Since its discovery, the magnetic excursion has been demonstrated in geological archives from many parts of the world.
This reduction in geomagnetic field strength resulted in more cosmic rays reaching the Earth, causing greater production of the cosmogenic isotopes beryllium-10 and carbon-14, a decrease in atmospheric ozone, and changes in atmospheric circulation.
Radiocarbon dating reveals that the tree was alive from 42,500–41,000 years ago, within the timeframe of the event.