Gault); (5) oxides of iron (staining the clay bright red when ferric oxide, red ochre; yellow when hydrous, e.g.
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.
The plant-bearing deposits next in age, which have yielded Angiosperms, appear to belong to the Cenomanian, though from Westphalia a few species belonging to the Cryptogams and Gymnosperms, found in deposits correlated with the Gault, have been described by Hosius and von der Marck.
The Upper Greensand and Gault, represented in Lincolnshire by the Red Chalk, run north-west from Irby, widening out as far as Kelstern on the east, and cross the Humber.
Of surface soil, glacial drift and impermeable gault clay and thence passed for a further depth of 70 ft.