316 J. E. Taylor— On the ' Red' and ' Norwich ' Crags. 



tlie sea over the previous site of the Fluvio-marine Crag, as v^^ell as 

 over the Eed Crag, the latter was also taken up and re-deposited. 

 This accounts for the extreme comminution of the shells in the 

 lower parts of the sections above mentioned, and also for the strong 

 evidences of false current bedding. Only the stronger shells, such 

 as Pectunculus glycimeris, Fusus contrarius, etc., could survive this 

 wear and tear, and these are the common Red Crag shells met with. 

 At the same time they are associated with undoubtedly Norwich 

 Crag forms, such as Mya trimcata, M. arenaria, Tellina oUiqua, 

 T. fretenuis, Buccinum undatum, Purpura lapillus, Littorina littorea, 

 etc. These lived in the sea where the Red Crag was being re- 

 deposited, and their remains thus became admixed with those of a 

 fornier period. Many of the shells last mentioned are more or less 

 fragile, and show that they could not have been subjected to the 

 same violence as their previously dej)osited associates. Of course 

 the greatest amount of re-deposition would be seen in the lower 

 beds, and the least in the upper, which is exactly the case inall 

 these sections. 



In conclusion, it seems to me clear that the old " Mammaliferous," 

 or Norwich Fluvio-marine Crag, was a north-easterly extension of the 

 Red Crag. When the depression of the area took place, there was 

 formed along it the Upper Norwich or " Chillesford " Crag. Be- 

 tween this and the Fluvio-marine beds, strata of sand were thrown 

 down and intercalated. But in Suffolk, where the Red Crag reached 

 such an enormous thickness, its upper portions were taken up and 

 re-deposited in false current bedded layers, where the stronger fossils 

 became mixed with the shells of the later period. Hence in such 

 areas this comminuted Red Crag, whose Norwich Crag forms have 

 given such trouble, is really the work of the sea where the Chilles- 

 ford beds were accumulated. At Sudbourne Church walks we find 

 this Upper Crag reposing on the Coralline Crag, and the same 

 phenomenon is visible in the railway cuttings near Aldborough 

 Station, where it rests in a denuded hollow of Coralline Crag. I 

 submit these views to Crag geologists, with the hope that they maj 

 assist in interpreting a perplexing phenomenon. If they are correct, 

 then we have, in the Eastern Counties, a perfectly marked and 

 unbroken sequence from the Coralline Crag up to the latest Drift 

 deposit. 



IsTOTIOJES OIF nvcEnvcoiE-s. 

 I. — On the Flotation of Sand by the Rising Tide in a Tidal 



ESTIIAKY. 



By Professor Hennessy, F.R.S., Vice-President of the Academy. 

 (Bead before the Royal Irish Academy, April 10, 1871.) 



DURING the course of a tour along our western coast, in the 

 summer of 1868, the following incident came under my notice ; 

 and, although I made a note of the facts at the time, I have never 

 hitherto made them the subject of a scientific communication : — 



