Cretaceous 144-65c million years
The north-facing slope in the purbeck strata now known as the durlston formation has been quarried from mediaeval times. Many of the small original underground quarries that worked directly from shafts to the surface have been uncovered while working the modern excavation method of open cast quarrying.
There are over 200 beds of purbeck stone.
This information is only a generalisation and the utilisation of certain beds can vary every time material is extracted from the quarry.