Lime is obtained from the Chalk and Greensand formations.
The chalk occasionally becomes phosphatized, as at Taplow (Bucks) and Lewes (Sussex).
Wanting Danian Upper Chalk Senonian Middle Chalk Turonian Lower Chalk Cenomanian Upper Green-sand Gault Albian Aptian Lower Green-sand Valenginian Urgonian Wealden Neocomian In the continental classification the deposits from the Gault downwards are grouped as Lower Cretaceous; but in Great Britain there is a strong break below the Gault and 'none above; and the Gault is therefore classed as Upper Cretaceous.
Flamborough Head, the South Foreland, Beachy Head and the Needles are examples of the fine scenery into which chalk weathers where it fronts the sea, and these white cliffs gave to the island its early name of Albion.
That the chalk was deposited in shallow, clear seas is indicated both by the character of the fossils other than foraminifera and by the relation of the chalk to the elastic portions of the series.
Except where the Humber cuts through a low chalk ridge, between north and south Ferriby, dividing it into the Wolds of Yorkshire and of Lincolnshire, the shores and adjacent lands are nearly flat.
Ver system, now entirely obliterated, drained into the Purbeck estuary and Wealden lake; but a subsequent depression led to the wide extension of the Chalk sea.
To the south the London basin is succeeded by the North Downs, an elevated ridge of country consisting of an outcrop of chalk which extends from Westerham to Folkestone with an irregular breadth generally of 3 to 6 miles, but expanding to nearly 12 miles at Dartford and Gravesend and also to the north of Folkestone.
On the stiff soils overl y ing the chalk it was formerly the custom to dig pits through the soil to the rock below.
Right back into British and even older times the main direction which commerce and travellers followed across southern and western England to the Straits of Dover and the Continent lay from Canterbury along the southern chalk slope of the North Downs to near Guildford, then by the Hog's Back to Farnham.