Microfossils can be obtained from the Grey Chalk Subgroup (formerly the Lower Chalk, minus the Plenus Marls) with great ease. This rock has a high clay content in comparison with the whiter chalks and breaks […]

Microfossils can be obtained from the Grey Chalk Subgroup (formerly the Lower Chalk, minus the Plenus Marls) with great ease. This rock has a high clay content in comparison with the whiter chalks and breaks […]