18 E. M. Brydone — Further Notes on the Triminingham Chalk. 



B. mucronata chalk of Hampshire, I have not yet found any Riigen 

 forms there, and this may well be more than a mere coincidence. 



Stratigraphy. 



In this department I have to acknowledge my indebtedness to 

 Mr. G. P. Bidder, who was staying at Mundesley during late 

 September and October of 1905, a time of very rough weather 

 and great variety of exposures. Though not a geologist, he took 

 great interest in the local geology and gave me much assistance in 

 many ways. Amongst other things he pointed out to me that in my 

 previous pamphlet I had overlooked the fact that the magnetic north 

 is about 20° west of true north, and that I ought to mention 

 that all my bearings were magnetic. I have, for convenience, 

 continued to use magnetic bearings in this paper. 



SoutJi Bluff. 



Very little further development has taken place here, but the 

 accuracy of the partly hypothetical presentation of the low southern 

 prolongation in fig. 2 of my previous pamphlet has been established 

 by fuller exposures both as to the continuity of the flint lines and 

 their identification with those to the right of A B. It also turned 

 out that at the furthest point to which they are shown extending 

 they bend sharply down, and all but the highest of the lines shown 

 to the right of A B come in on the slope. The highest of these was 

 found to be dipping at quite 75° almost due south. (This very high 

 dip on the south side of a ridge is by no means uncommon elsewhere 

 in this area.) 



A great number of cavities have recently appeared in the upper 

 beds of the southern part of the bluff, and it appears as if these 

 cavities expand as they penetrate the bluff. This is just what would 

 be expected if they were cavities formed in a cliff facing to the 

 south or south-west, and tends to confirm the view that this part of 

 the bluff, at any rate, is the remains of a headland which faced a sea 

 lying to the south or south-west. 



A good deal of the sand in the gap between the two parts of the 

 bluff has been cleared away and the south-easterly face of the 

 northern part exposed to a point directly behind and on the same 

 level as the northern end of the southern part and only 8 yards 

 away from it (Plate II, Fig. 1). The marked difference in the 

 physical characters of the two parts remains unaffected, and the 

 conclusion that they are separated by a fault seems now inevitable 

 if the north part is not an erratic, as to which no further evidence 

 has been obtained. I have found a single specimen of 0. lunata in 

 the northern part. 



North Bluff. 



Here there have been some most interesting developments owing to 

 the rapid erosion which has taken place, and is still proceeding. 

 A great deal of erosion took place in the Winter of 1900-1 

 all round the bluff, and I was fortunate enough to obtain through 

 Mr. Savin, of Cromer, the assistance of a local amateur photographer, 



