I don't know about other nuclear physics type phenomena, but some reasonably unthinkable things that probably happened include the earth being completely encase

I don't know about other nuclear physics type phenomena, but some reasonably unthinkable things that probably happened include the earth being completely encased in ice[1], all of the continents colliding into a supercontinent[2], a volcano big enough that it was essentially a crack in the earth with basalt lava (>1000°C) pouring out at 4x the flow of the Amazon for a week (in which it flowed hundreds of miles)[3], or (one of my favorites, though it's just kind of neat and not so mind-blowing) ammonite seashells that have had the original calcite shell naturally replaced with pyrite (fool's gold) so there are completely natural metallic fossils[4]. [1]: www.snowballearth.org [2]: https://en.wikipedia.org/wiki/Pangaea https://en.wikipedia.org/wiki/Pangaea [3]: http://en.wikipedia.org/wiki/Columbia_River_Basalt_Group http://en.wikipedia.org/wiki/Columbia_River_Basalt_Group [4]: https://www.google.it/search?q=ammonites+replaced+with+pyrite+morocco https://www.google.it/search?q=ammonites+replaced+with+pyrit...