THK CRETACEOUS SYSTEM 499 



In Hampshire, near Alton and Selborne (sec map, Fig. 157), the 

 general succession is as follows : 



Feet 

 5. Soft greenish sands without fossils . . . 2 to 15 



1. Miiliiistniu- with beds of calcareous stone . . 80 to 100 

 3. Sandy marls with Sch. rostrata and Jnoc. sulcatus 30 to 50 



2. Dark clays with Hoplites interruptus . . . about 100 

 1. Green sands with phosphatic nodules . . . 3 to 15 



About 240 



From the malmstone Schlcenbachia rostrata, Hoplites auritus, 

 Anisoceras armatum, Area carinata, and Pleuromya mandibula 

 have been obtained, and there is no doubt that it represents the 

 greater part of the Upper Gault of Folkestone. 



In Wiltshire and the Isle of Wight there is a similar succession, 

 and the beds are well exposed in the Undercliff along the south 

 side of the Isle of Wight, where the following are the main sub- 

 divisions : 



Feet 



P. asper zone Sands and chert-beds (few fossils) . . about 30 



. rostrata J Soft sandstones and sandy malm . . ,,70 



zone \ Dark-grey sandy clays . . . ,,45 



Lower Gault Blue clays with Hoplites denarius, etc. . ,, 100 



The "Gault" passes down into the "Carstone" (see p. 481), 

 which Mr. A. Strahan is inclined to regard as representing the 

 zone of Douv. mammillatum ; but that fossil has not yet been found, 

 and the question remains undecided. 



In South Dorset the succession is similar, but the base of the 

 Selbornian is sharply denned by a thin layer of quartz pebbles, 

 while the Lower Gault becomes more and more sandy as it is 

 traced westward. The zone of Sch. rostrata consists of green sands 

 with beds of calcareous sandstone, and there is always a well-marked 

 zone of Pecten asper at the top. 



In Devon the beds are well exposed in the cliffs between Lyine 

 Regis and Sidmouth, the base of the Selbornian gradually passing 

 over the Lower Lias and across the Keuper marls till it rests on 

 the Keuper sandstones (see Fig. 131, p. 396). At the base near 

 Lyme and Axmouth there are still some few feet of clay (Lower 

 Gault), but westward this either thins out or passes into sand. At 

 Beer and near Beer Head the succession is as follows : 



Feet 



Zone of / Hard calcareous sandstone (few fossils) . . about 10 

 P. asper \ Sandstones with chert-nodules, Exogyra digitata 60 



Zone of J Soft grey sands passing down into dark-green 

 S. rostrata \ clayey sand, Dosiniopsis caperata ... 90 



160 



