436 [June 12, 



be readily extracted. There is here no mixture of fluviatile and 

 marine remains, so that this instance offers evidence of submer- 

 gence and subsequent elevation. The marine gravel is covered 

 by laminated blue clay, derived from adjoining till, and it passes 

 upwards into yellow silt and sand, the lamination of which is 

 much contorted. 



Till. The unstratified blue clay on the Norfolk coast alluded 

 to under this name, resembles, in colour and composition, that 

 which is found on the coast of North Wales and the east of Ire- 

 land, differing only from these deposits in the nature of the im- 

 bedded fragments. These seem to have been all of them trans- 

 ported from the north, and they are heaped in irregular hummocks, 

 the height of the cliffs depending on the amount of this material. 

 The till does not seem to pass by any gradation from the fresh- 

 water deposits, nor is the surface of the latter disturbed at the 

 contact as if the sea-bottom had been ploughed up by the passage 

 of icebergs. The contorted strata (accurately described by Mr. 

 Lyell) are always either above or between the masses of till. 



The transported blocks dispersed through the till consist of 

 granite, gneiss, mica-slate, and trappean rocks, often in an angular 

 state, and not rubbed. Some fragments, however, show scratches 

 and other markings like those attributed to the grinding of a 

 glacier, and the author states that he had already observed scratches 

 on boulders in Caernarvonshire, and alluded to them as charac- 

 teristic of the epoch, before such markings were attributed to the 

 action of ice. 



Notwithstanding the distance which separates the till of the 

 coast of Norfolk from that of North Wales and Ireland, the author 

 recognises a common character pervading the whole, which he attri- 

 butes to their having had a common origin, being derived from the 

 north, and he considers that the cause of the deposit of this 

 boulder clay covered with sands, loam, &c. of a yellow colour, 

 seems to have acted but once, the same appearances not recurring. 

 There is still, however, one striking difference observable in the 

 two localities, since the Norfolk beds are much contorted, while 

 this is not the case in North Wales. These contortions are referred 

 by the author to the movements connected with the final upheaval 

 of the coast ; but since, where the contortions are most violent, 

 the underlying chalk is undisturbed, as between Sherringham and 

 Weybourne, he supposes that the till has exercised some influence 

 in producing these singular appearances. 



The author observes, in conclusion, that these deposits on the 

 cliffs, produced by the northern drift, ought to be carefully dis- 

 tinguished from ordinary raised beaches, the phenomenon in the 

 former case having been produced by the submergence and subse- 

 quent elevation of land which had been long existing in that state. 

 He does not pretend to decide the extent of the submergence. 



