They are found in the Lower Greensand, or Upper Neocomian series, in the Atherfield Clay at Stopham, near Pulborough; occasionally at the junction of the Hythe and Sandgate beds; and in the Folkeston beds, at Farnham.
At Woburn, Leighton, Ampthill, Sandy, Upware, Wicken and Potton, near the base of Upper Neocomian ironsands, there is a band between 6 in.
The Inferior Cretaceous rocks include the Neocomian and Gault (Albian and Aptian) subdivisions, and form the flanks of the mountains in the Tell.
The lowest beds consist of red grits which contain Neocomian fossils, while the middle and upper Cretaceous consist chiefly of limestone and chalk.
Griesbach, basic volcanic rocks are interbedded with the lowest part of the plant-bearing series, and enormous outbursts took place during the Neocomian period.