454 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



division of the Eed Crag ; that the Chillesford series filled up and 

 levelled the irregular surface of the Red and Coralline Crags, over 

 the highest portion of both of which it extends ; that reefs of the 

 Coralline Crag divided the Red-Crag sea into different areas, with 

 local variations in the distribution of the Molluscan fauna; and 

 that the area north of Aldborough was not only separated from 

 the more open sea to the south, but was also more subject to the 

 influence of fresh water, the beds at once being more littoral and 

 containing a larger number of freshwater Testacea. The Chillesford 

 Clay was traced to Southwold, where it holds the same relation to 

 the shelly sand-beds as it does in the ChUlesford and Sudbourne 

 districts. 



Beyond the few pits in the neighbourhood of Southwold and 

 "Wangford there are no sections of the crag in north Suffolk. On 

 the borders of Norfolk, however, we reach a section of great interest, 

 which was discovered a few years since by Mr. Rose, of Yarmouth. 

 It is in a brick-pit in the parish of Aldeby, at a distance, by road, 

 of four miles from Beccles. 



The section is as under : — 



Fig. 27. — Pit at Aldeby. 



feet, 



a. Valley-gravel 2 to 4 



3. Chillesford clay 5 to 7 



3'. Light-coloured sands, with seams of fine gravel and of shells 6 



A boring has been carried through sands 10 feet deeper, when the tool was 

 stopped by a bed of gravel. 



The Chillesford Clay is well developed, with its usual characters 

 of a laminated grey micaceous clay ; but no shells have been found 

 in it here. Large flints, little worn, and fragments of wood are 

 occasionally myt with ; and Mr. Dowson informs me that he found 

 in the upper part of the clay the condyle of the femur of Elephant. 

 The marked feature of the section is the occurrence of the Crag 

 shells, not, as usual, with the larger portion in a comminuted state, 

 but entire and with a number of double shells, many in the same 

 position as when living. Occasionally large masses of flint are found 

 in the sand. I saw one which weighed | cwt. ; and adhering to it were 

 numerous basal plates of the Balanus porcatus. The undisturbed 

 condition of the beds offers an unusually favourable opportunity of 

 investigating the fauna of this part of the series free from the intro- 

 duction of any foreign element, — an opportunity of which Mr. W. M. 

 Crowfoot, and Mr. E. T. Dowson, of Beccles, have taken excellent 



