470 • PLIOCENE. 



of Lyell) consist of sand and laminated clay, with Stone-bed at 

 the base, altogether about lo feet thick. They rest on the Chalk, 

 and have been traced to Lower Sherringham and Runton, east- 

 wards of which they occur for some distance at or beneath the 

 sea-level. The beds reappear at Trimingham, and they have been 

 observed inland at Honing, besides at the localities previously 

 mentioned.' (See Fig. 8i.) 



Ironstone nodules, consisting of a hard shell of iron-sandstone with a nucleus of 

 clay iron-ore or ochre, abound in the Norwich Crag Series. They may have 

 originated from the segregation of iron-oxide around clay balls or clay " pebbles," 

 which are often present in the series, and from whicli to the ironstone nodules 

 gradations in structure may be traced.* (See p. 433.) 



The accompanying diagram is intended to show the general 

 relations of the Norwich Crag Series to the Red Crag and to the 

 Cromer Forest Bed Series : — 



CROMER FOREST BED SERIES. 



This Series, so noted for the Mammalian remains which it has 

 yielded, occurs along the base of the cliffs and fore-shore between 

 Weybourn in Norfolk and Kessingland in Suffolk, although it is 

 not persistently exposed for the entire distance, and is indeed 

 usually much obscured by recent accumulations. It occurs below 

 the Glacial Drift and above the Weybourn Crag ; but no sections of 

 the beds have been observed inland. It comprises beds of sand 

 and gravel, laminated clays and peaty beds, attaining a thickness 

 of from 20 to 30 feet. 



^ C. Reid, Geol. Cromer (Geol. Survey), p. il ; see also Geol. Fakenham, 

 p. II ; and Lyell, Phil. Mag. (3), xvi. 361. 

 ^ P. Geol. Assoc, v. 514. 



