PBESTWICH — CRAG-BEDS OP SUFFOLK AND NOKFOLK. 



465 



The Westletou beds here exhibit the characters we have noticed 

 further south, consisting essentially of flint-pebbles with numerous 

 white quartz-pebbles and a small admixture of pebbles of some pecu- 

 liar varieties of siliceous sandstone, chert, and slate rocks ; mixed 

 with them is a considerable quantity of drift-wood, both in large 

 pieces and in matted small branches. Further, the basement bed 

 of this series again often contains at places clay-pebbles derived 

 from the Chillesford Clay *. 



At this part of the coast the Westleton beds become more argil- 

 laceous, containing several subordinate beds of laminated grey 

 clays without fossils. These clays sometimes replace, in great part, 

 the sands and shingle, whence Mr. Gunn has applied to this series 

 on the Norfolk coast the term of " the laminated clays," which 

 often well expresses their character f. In this area the Westleton 

 beds rarely exceed 25 feet in thickness ; and where the Forest-bed 

 rises higher, as at Paston Cliff (fig. 36), or where the underlying beds 

 have been denuded before the deposition of the Boulder-clay, they 

 are sometimes wanting. 



Fig. 36. — Section in Paston Cliff. 



7. Sands, gravels, and laminated loams (base of 7). 

 6. Boulder-clay (lower division). 

 5. Sandy shingle. 

 5'. Elephant-^d. 

 4. Forest-bed. 



As we proceed further northwards these beds assume a fluvio- 

 marine character. Just south of Mundesley a thin seam of clay with 

 freshwater shells, consisting of 



Anodonta cygnea, 

 Unio pictorum, 

 Sphterium corneum, 



Pisidium amnicum, 

 Bythinia tentaculata, 

 Valvata piscinalis, 



which I have already described J, appears at their base ; whilst on 

 the north of Mundesley marine sheUs are intercalated with seams 



* I had not found any shells on this part of the coast ; but Mr. Grunn pointed 

 out to me this summer a spot about half a mile north of Bacton Gap, where we 

 procured from the lower bed of the Westleton shingle the following shells : — 

 Purpura lapillus, Littorina rudis and L. littorea, Mytiliis eduUs, and a species of 

 Scalaria, all much decayed. Some years since, Mr. Green, of Bacton, stated that 

 the Crag was found in Bacton cliff; but his statement remained discredited. 

 This was no doubt the bed to which he referred. 



f I hesitate to adopt this term, as the character is again repeated in the beds 

 above the Lower Boulder-clay in the same cliffs, as well as in the Chillesford 

 beds below. Nor in any case is a mineral designation convenient, especially for 

 such variable beds. (See also my paper on the Mundesley Section, in the 

 ' Geologist' for 1861, p. 68.) J ' The Geologist ' for 1861, p. 68, . 



VOL. XXVII. PART I. 2 K 



