For the first time scientists have been able to reconstruct the chemical composition of rainwater from 300 million year old minerals, allowing them to unpack some of the history of Brittany and Western France since the rain fell in the late Carboniferous period, just before the time of the dinosaurs. The results point to the area being mountainous and originally located close to the Equator. This work is presented at the Goldschmidt Geochemistry congress in Barcelona.
source https://phys.org/news/2019-08-scientists-history-western-france-written.html