Solar geology: deducing the Sun's pre-telescope history
https://academic.oup.com/astrogeo/article/52/2/2.13/206404
Evidence of a Monstrous, Ancient Solar Storm Found Hidden in Greenland's Ice https://www.popularmechanics.com/science/environment/a268179...
BC 660 beryllium-10 / chlorine-36 spike https://www.popularmechanics.com/science/environment/a268179...
AD 774–775 carbon-14 spike https://en.wikipedia.org/wiki/774%E2%80%93775_carbon-14_spik...
AD 993-994 carbon-14 spike https://www.nature.com/articles/ncomms2783
See Also: Atmospheric Production of Carbon-14 https://en.wikipedia.org/wiki/Carbon-14#Natural_production_i...