Mr. J. Prestwich on the Crag-beds of Norfolk and Suffolk. 399 



Character and Thickness. Localities. 



.'£ ^ f h. Sand and comminuted shells, 6 ft. Sudbourne and Gredgrave. 



R §§ J g. Comminuted shells and remains of Bry- Sutton, Sudbourne, Ged- 



% _r 1 ozoa, forming a soft building-stone, grave, Iken, Aldboro'. 

 J? J 30 ft. 



f f t Commiuuted shells, with numerous entire Sutton, Iken, Orford, High 



small shells, 5 ft. Gredgrave. 



e. Sands with numerous Bryozoa, and some Sutton, Broom Hill. 



small shells and Echini, 12 ft. 



d. Comminuted shells, large, entire, and Sutton, Broom Hill, Sud- 



double shells, and bands of limestone, bourne. 



15 ft, 



c. Marly beds, with numerous well-preserved Sutton, Ramsholt. 



and double shells, 10 ft. 



b. Comminuted shells and Cetacean remains, Sutton. 



4 ft. 



a. Phosphatic nodules and mammalian re- Sutton. 



mains, 1 ft. 



Mr. Prestwich then stated the localities at which these subdivisions 

 of the Coralline Crag are exposed, and proceeded to discuss the 

 geographical distribution of the existing species ia the several zones, 

 and the present range of the organic remains. He agreed in the 

 opinion that the greater number of the Mammalian remains are ex- 

 traneous fossils — but regarded those of a whale as truly contem- 

 poraneous, and probably also the teeth of the Rhinoceros and Mas- 

 todon, while the bones that are more or less drilled he considered to 

 be derived. The occurrence of a large block of porphyry in the 

 basement-bed at Sutton was considered a proof that a considerable 

 degree of winter cold had been attained at that period, as it would 

 be difficult to account for its presence in that bed except by ice- 

 action ; the author also enumerated the physical conditions which 

 seem to be suggested by the mineral character and the structure of 

 the several zones, inferring, from the peculiar mixture of southern 

 forms of life with others of a more northern type, that at this early 

 period the setting-in of conditions of considerable cold had com- 

 menced. 



With the aid of Mr. Gwyn Jeffreys the author had revised the 

 list of Mollusca from the Coralline Crag ; and he gave a Table in 

 which the range of the species in space, depth, and time was given, 

 and an analysis of their synonymy by Mr. Jeffreys. He also dis- 

 cussed the relations of the Coralline Crag, with its foreign equi- 

 valents, agreeing in the conclusion that the Crag Noir is a stage 

 older than it, while the destruction of beds of the age of some of the 

 older Crags of Belgium have furnished many of its derived fossils. 

 In conclusion the author described the distribution of sea and land 

 at the period of the deposition of the Coralline Crag, as suggested 

 by the affinities of the fossils of that deposit. 



