Next in order come the Greensands and Gault, which lie at the base of the Chalk escarpment, between that formation and the Oolites.
The narrow strip of Greensands appearing from beneath the Chalk escarpment on its northern side is crowded with small towns and villages on account of the plentiful water-supply.
The next deposits, as the scarps are approached, are greensands of "Selbornian" age, succeeded by Cenomanian, and locally by Turonian, sands.
These Cretaceous limestones are interbedded with glauconitic greensands, as at Moeraki Point in eastern Otago.
Geologically the region is made up of Carboniferous limestones, clay slates and sandstones, containing anthracite and coal; of Cretaceous marls, chalk, sandstone and greensands - chalk cliffs, in fact, accompany the Don for 200 m.; and of Miocene limestones and clays.