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between East Anglia and the 

 Rhine, from rocks in the basin of 

 which the mica was probably 

 derived), it appears that the con- 

 ditions under which the two 

 formations originated were some- 

 what different. While the Eed 

 Crag* was apparently deposited in 

 confined bays or inlets, the Nor- 

 wich Crag beds occupy a much 

 larger and more exposed area (see 

 map, fig. 3, p. 714). The latter 

 are not so constantly fossiliferous ; 

 they are more or less horizontally 

 stratified ; and they never present 

 the highly inclined beach-like 

 bedding of the Red Crag. The 

 Eed Crag, moreover, where its 

 junction with the London Clay is 

 exposed, as is the case in places 

 from Tattingstone and Walton in 

 the south, to Bawdsey, Ramsholt, 

 and Sutton in the north, does nob 

 attain a greater thickness than 

 about 20 or 25 feet. At Butley 

 and Chillesford, farther north, 

 where the base of the Crag dips 

 below the water-line, it may per- 

 haps be somewhat, although not 

 much, thicker. When we pass 

 north of Aldeburgh, however, 

 where the Icenian (Norwich Crag) 

 Beds come on, we find that the 

 Crag thickens very rapidly, attain- 

 ing 134 feet at Leiston 1 ; at 

 Southwold, 9 miles farther north- 

 west, it reaches 140 feet below 

 sea-level, with a total thickness 

 of 147 feet 2 ; while in a 'recent 

 boring at Lowestoft, mentioned by 

 Mr. C. Reid, its base was not 

 reached at 180 feet. 3 



Deposition and subsidence in 

 East Anglia during the Norwich- 

 Crag era seem to have proceeded 

 pari passu, as was the case during 

 the Pliocene Period in Holland, 

 although not to so great an extent 

 as in that country. This state of 

 things was due in both, however, 

 to the same cause. The greatest 



From information kindly supplied by Mr. W. H. Dalton, F.G.S. 



Mem. GeoJ. Suit. (1887) 'Southwold' p. 79. 



Summ. of Progress of Geol. Surv. for 1898 (1899) pp. 145-46. 



M 





