25. Ancient rocks: the oldest rocks on Earth, the moon-forming event, and good old geology

In this episode we cover the oldest rocks on Earth, stretching to our planet's formation 4.54 billion years ago. We explain where the rocks are found and how we date them using radioactive elements, including the geology of Greenland, Canada and Australia. We also discuss a mythical rock that was used to summon troops by King Alfred the Great during the Battle of Ashdown in Britain in 871 CE. Remember to follow us on social media for all the latest episode info and cool Earth facts Instagram and TikTok @coepod X @thecoepod