The Braksøya Formation is a geologic formation in the Ringerike and Modum areas in Buskerud, Norway, where it overlies the Bruflat Formation and the Skien and Holmestrand areas where it overlies the and respectively. The formation, deposited in a shallow Caledonian foreland basin at the edge of a closing Iapetus Ocean, preserves fossils dating back to the Sheinwoodian stage of the Silurian period.