The End of Trimingham Chalk Bluff. 293 



during the last twenty years justifies (in our opinion) the following 

 conclusions : — 



A little to the east of the Trimingham section, chalk, with a fairly 

 level top-surface (like an old sea-floor), lies only a few feet helow high- 

 water mark. Hereahouts it is covered by a normal boulder- clay, 

 which at this place forms the base of the Contorted Drift, without 

 remains of the Forest Bed or Weybourn Crag. This clay, as a whole, 

 contains many boulders, some of solid, some of remanie chalk, and 

 occasionally one of sand and gravel, and we now seem justified in 

 concluding the Trimingham masses to be erratics, not ancient stacks 

 of chalk. 



Though the gravel mass at Triminjjhara is, in at least one respect, 

 unique, we meet occasionally with boulders of stratified sand or gravel. 

 In 1892 there was one, also with its bedding vertical, in the clifi^s to 

 the west of Cromer. It had practically disappeared before our next 

 visit, and the place, not far from the end of the lower promenade, 

 is now overgrown with grass. ^ This was a more normal sandy flint- 

 gravel than that at Trimingham, and it contained numerous fragments 

 of marine shells. It was in the usual bedded clayey sands of the 

 Contorted Drift, and so far as we remember was some 40 feet (perhaps 

 more) above the sea. In one respect the?e gravel and sand boulders 

 are interesting, for the material is incoherent; one could bring it 

 down rapidly with a rake. It therefore could not have been 

 transported unless it had been frozen into a solid mass. In other 

 words, it must have been saturated with water and that have been 

 converted into ice. If it tumbled from a cliff upon an ice-sheet, 

 we are forced to assume that either the latter must have been very 

 thin or the former very high. For an ice-sheet to pluck up from the 

 sea bed a block of this shape would be difficult and still more so to 

 turn it from a horizontal to a vertical position. If we could assume 

 it to have fallen from a cliff upon an ice-foot, and to have been floated 

 away for some little distance, the problem would be simplified, but if 

 so (or in the other case named above) the cliff can hardly have been 

 situated north of the present positions of the boulders, for that 

 hypothesis introduces obvious difficulties. Be this as it may, we 

 need a low winter temperature to convert into solids masses so large 

 as these. It cannot have been less, and may well have been more, 

 than in Spitzbergen at the present day, where the January temperature 

 is about — 10° r. with a mean annual temperature of about 18°. 

 That of the Norfolk coast in the Cromer district is about 30° for mid- 

 winter, with a mean annual temperature of about 49°, so there must 

 have been an approximate drop in the one case of 40°, in the other of 

 31°, which imply a greater fall than is demanded by the indications 

 of the Glacial Epoch in the more central parts of Europe.^ But to 

 discuss that interesting topic would unduly lengthen this paper, so 

 we must restrict ourselves to calling attention to the above-mentioned 

 facts, and hope to consider them more fully on a future occasion. 



^ So far as I remember, it approached 20 feet in length, and was at the base 

 a little wider than that, but I could not do more than make a rough sketch of 

 it as I was going back to my hotel to return to London. (T. G. B.) 



" T. G. Bonney, Brit. Assoc. Eep., 1910, pp. 22, 23. 



