TIIK PLIOCEXE SEKIKS 599 



with occasional seams or patches of shells, and different local 

 names were given to different portions of the group before it 

 was ascertained that they all belonged to one division of the Crag. 



Mr. F. W. Harmer remarks that " the Norwich Crag Beds are 

 separated by a considerable interval [of time] from any part of the 

 Red Crag. Their molluscan fauna has a much more recent 

 character ; they never exhibit the highly inclined bedding so 

 characteristic of the Red Crag, and they attain a much greater 

 thickness than the latter ; they occupy an entirely different 

 area, and appear to have originated under somewhat different 

 conditions." 17 



The Norwich Crag appears to cut off the Coralline Crag abruptly 

 near Aldeburgh (see Fig. 199), and it probably also truncates the 

 Red Crag, for the latter has never been recognised north of that 

 place, while the newer crag thickens northward very rapidly. In a 

 boring at Leiston, only 2 miles from the border of the Coralline 

 Crag, it was found to be 134 feet thick, at Southwold 147 feet, and 

 at Lowestoft 180 feet were traversed without reaching its base. 



Norwich Crag is not well exposed in any cliff-section, but a few 

 feet of it are seen at the base of the cliffs near Southwold and 

 Easton Bavent, where the succession is as follows : 



Feet. 



Glacial Beds Bedded sands with flint pebbles. . up to 7 

 Chillesford Beds Bedded sand and clay ... ,, 12 

 Norwich Cray Sand with three layers of shells . , , 4 



At Aldeby, on the north side of the river Waveney, a brickyard 

 exposes a similar succession, and about sixty-six species of Mollusca 

 have been obtained from the shelly sands. A special feature of this 

 locality is that many of the bivalves occur with united valves in the 

 position of life ; they include Mya arenaria, M. truncata, Yoldia 

 oblongoides, Y. lanceolata, Lucina borealis, Mactra ovalis, Scrobicularia 

 plana, Tellina lata, and T, obliqua. 



Farther west along the same valley this crag is exposed in many 

 pits near Norwich, Bramerton, and Brundall. The beds vary from 

 15 to 20 feet in thickness and consist mainly of sand with 

 occasional seams of brown clay, and have generally a bed of rolled 

 flints and pebbles at the base, in which mammalian bones and 

 teeth have been found. 



Ohillesford Beds. There has been much difference of 

 opinion about these beds and their relation to the Norwich Crag. 

 The geological surveyors (Messrs. W. Whitaker and C. Reid 18 ) 

 distinguish between Chillesford Crag and Chillesford Clay, regarding 

 the former as part of the Norwich Crag and the latter as a 

 separate and higher horizon. Mr. Harmer agrees with these 



