346 Mr. Lyell on the Boulder Formation, 



The freshwater strata associated with the boulder forma- 

 tion above mentioned occur for the most part in patches at the 

 bottom of the drift, and immediately above the subjacent chalk 

 and crag, where the latter is present, as may be seen at a va- 

 riety of places between Happisburgh and Runton near Cro- 

 mer. The two spots where it is most largely developed are 

 at Mundesley and Runton. At the latter place it underlies 

 the drift and rests immediately on chalk, with the occasional 

 intervention of marine crag; while at Mundesley it occupies 

 for a certain space the whole cliff, taking the place as it were 

 of the drift, and appearing in part to be of contemporaneous 

 origin, and in part of subsequent date and superimposed. 

 Everywhere it contains the same species of shells, and as these 

 are almost without exception identical with well-known Bri- 

 tish species, it is evident that the entire formation of the mud- 

 cliffs, whether freshwater or drift, belongs to the latest part of 

 the tertiary period, the only doubt being whether it should 

 not rather be considered as post-tertiary or referable to a class 

 of deposits which contain exclusively shells of recent species. 



I mention at once this conclusion, because the recent origin 

 of the drift adds a peculiar interest to the great derangement 

 and change of position which it has undergone since its 

 deposition. In no other parts of our island, or perhaps of 

 Europe, are there evidences of local disturbance on so great 

 a scale and of an equally modern date, for there are proofs of 

 the movement both downward and upward of strata several 

 hundred feet thick for an extent of many miles ; together with 

 most complicated bendings and foldings of the beds and the 

 intercalation of huge masses of chalk, and what is no less per- 

 plexing and difficult of explanation, the superposition of con- 

 torted upon horizontal and undisturbed strata. 



The line of coast in which the formations above alluded to 

 are displayed was well described in Mr. R. C. Taylor's Geo- 

 logy of East Norfolk, published in 1827, and afterwards in 

 Mr. Woodward's Outline of the Geology of Norfolk, 1833. 

 Both these papers are the result of a careful survey of the 

 coast, and contain original observations of great merit. In 

 both are given coloured sections of the cliffs, from which a 

 good general idea of their structure and composition may be 

 derived. A memoir was also read to the Geological Society 

 in January 1837, by the Rev. W. B. Clarke, in which among 

 other remarks he insists on the necessity of separating the 

 diluvium of Norfolk from the crag *. 



My own observations on the coast of East Norfolk were 

 made first in the year 1829, and afterwards in 1839; and as 



* Geological Transactions, 2nd series, vol. v. part ii. p. 363. 



