1/2 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 17, 



On visiting the cliffs with Mr. Gunn, I found their structure to be 

 as he had described it. 



The oolitic boulder clay which forms the summit of the cliff, and 

 is covered, more or less, in the interior by masses and patches of the 

 sands and gravels of the denuded upper erratics, rests on a thick 

 mass of sand. This sand is clayey in its lower part, and frequently 

 exhibits lenticular masses of blue clay, like that of the Cromer Cliffs. 

 I saw some boulders of gneiss on the beach, and though, during a 

 rapid examination, we found none actually imbedded, Mr. Gunn as- 

 sured me he had seen them in the cliff. 



From the Journal of the Royal Agricultural Society 1 reproduce 

 the following description of the boulder-clay of Norfolk, where it 

 approaches the Yarmouth estuary. I quote it in order to show how 

 that description harmonizes with the discovery made by Mr. Gunn. 



" Towards the termination of the cliffs near Happisburgh, the 

 thickness of the boulder-clay diminishes, its upper surface sinks 

 beneath the level of the sea, and disappears under the sand-hills and 

 alluvium of the Yare. Detached portions of it are, however, met 

 with in the ' hards ' or ' holmes ' which rise like islands from among 

 the alluvial deposits. In composition this clay is somewhat different 

 from the clay of Cromer Cliffs, and consists of a mixture of blue clay, 

 such as occurs in those cliffs in the yellow clay and sand. In this 

 form it is the grey clay-marl of East Flegg, described by Marshall. 

 South of the Yarmouth estuary it is again visible between Gorlston 

 and Lowestoft, occupying the upper part of the cliff with a large 

 development of crag-sand beneath and a thin covering of the gravel 

 and sand of the upper erratics above it. 



" Following it up the valley of the Waveney, we find it holding the 

 same relative position to the two sandy deposits, except where, by the 

 denudation of the upper sand, the clay has been exposed over large 

 areas in the southern boundaries of Norfolk, and over still larger 

 areas in the north of Suffolk. 



"Oolitic detritus increases in quantity as the boulder clay is traced 

 towards the west in the river-sections, and in the clay-pits which 

 have been so abundantly opened throughout the district. This 

 detritus consists of fragments of Kimmeridge Clay and other oolitic 

 rocks, with their characteristic fossils, among which the vertebrae of 

 the saurians and the * turtle-stones' or septaria of the Oxford Clay 

 are very abundant." 



In the sand below the boulder-clay, Woodward had traced shells 

 which he considered crag- shells, as far as Bungay in the valley of the 

 "Waveney. I had traced it still further to the west, but without 

 shells, as far as Harleston. I also traced it up the valley of the 

 Wensom as far as Swan ton Morley. 



Mr. Gunn considers that the shells are not in situ, but derived 

 from the Crag. This, however, appears to me a point of very little 

 importance. Among deposits in which the greater portion of the 

 mammals and molluscs are of existing species, we should be led into 

 serious errors by relying on particular species. We must be guided 

 chiefly by physical evidence, and when we have recourse to organic 



