THE MAGAZINE 



OF 



NATUEAL HISTORY, 



JULY, 1839. 



Art. I. — On the Relative Ages of the Tertiary Deposits commonly 

 called " Cray, " in the Counties of Norfolk and Suffolk. By 

 Charles Lyell, Esq., V.P.G.S. 



In the course of last year I visited several parts of the coun- 

 ties of Norfolk and Suffolk, and examined the tertiary depo- 

 sits there called "crag," principally with a view of satisfying 

 myself respecting the following points : — First, the direct su- 

 perposition of the red to the coralline crag, as first pointed 

 out in 1835, by Mr. Charlesworth ; * Secondly, whether the 

 remains of Mammalia were really imbedded in regular and 

 undisturbed marine strata in the Norwich crag, as affirmed 

 by the writer above mentioned ; Thirdly, whether the propor- 

 tion of recent shells, as compared with the extinct, was de- 

 cidedly larger in the Norwich crag, so as to indicate a pos- 

 teriority in age relatively to the Suffolk crag. 



Red Crag of Suffolk overlies Coralline. — First, in regard 

 to the superposition of the red to the coralline crag, I found 

 this fact exhibited in distinct sections at Ramsholt and Tat- 

 tingstone, as indicated by Mr. Charlesworth, and in quarries 

 near Sudburn, to which I was directed by Mr. Bunbury. In 

 both the former localities, — Tattingstone and Ramsholt, — the 

 red crag rests on the denuded surface of the older or coralline 

 deposit. 



At Sutton, near Woodbridge, in Suffolk, a large excavation 

 has been made at the point of junction ; and Mr. W. Colches- 

 ter, a zealous collector of the fossils of these beds, had the 

 kindness to cause an artificial section to be made, expressly 

 to enable me to see more distinctly the manner of the junc- 



1 London and Edinburgh Phil. Mag. August, 1835, p. 81, 

 Vol. III.— No. 31. n. s. 2 k 



