Fisher — Denudations of Norfolk, 551 



tween them exhibits chalk at low water, consisting of identically the same beds as 

 those constituting the bluffs, and one of these beds is very marked from the abund- 

 ance of a small oyster.^ The chalk on the shore is even more disturbed than that 

 in the cliff, some of it standing at a very high angle. But what is especially worthy 

 of remark is that the Boulder-clay also appears on the shore, intermixed with the 

 Chalk, and partaking of the same contortions. At one place a very distinct synclinal 

 was observed, where the Boulder-clay was invested on three sides by Chalk. I 

 conceive the elevation of these great masses of Chalk to have been due to a kind 

 of creep. But there are other features about the bluffs which are very puzzling. 

 One of these is the cavities they contain, filled with stratified alternations of cal- 

 careous sands and carbonaceous matter, evidently of ancient date. These cavi- 

 ties led me to suppose these masses might have formed needles or rocks in the 

 Glacial sea. But, if so, it is difficult to conceive how the large flints, usually 

 covering the Chalk surface, could have been preserved upon their upper parts in 

 situ, as they are. 



During the period of subsidence — intermediate between the deposition of the 

 Lower Boulder-clay and middle Drift of Mr. Wood, when those deposits were formed, 

 which he distinguishes by the letters z, k — it is probable that a great amount of de- 

 nudation took place upon what is now the Chalk district of Norfolk. 



Mr. Trimmer places the "reconstructed Chalk" in this period, and I agree 

 with him, differing from Mr. Wood, who fixes it at an earlier period. But in using 

 this term, "reconstructed Chalk," I must guard myself against being misunder- 

 stood. 



Norfolk geologists are accustomed to speak of the disintegrated, and somewhat 

 deranged, Chalk in the upper portions of their vast chalk-pits, as "reconstructed 

 Chalk." The examples which have been pointed out to me, as, for instance, that 

 at Eaton, to which I was conducted by Mr. Taylor, I believe to be nothing more 

 than Chalk disintegrated in situ by the percolation of atmospheric water.^ But on 

 the north-eastern boundary of the Chalk area chalky matter in a very different con- 

 dition is to be met with. It is to be seen in a very typical form about Kelland and 

 Weybourne. The chalky loam is usually cream coloured, and is much of it hori- 

 zontally stratified, and contains thin bands of sand and laminse of mica. This is 

 especially notable in a pit on Kelland heath. There the section of the quarry has 

 a fine ribboned structure, observable in the smallest specimens, exactly like some 

 of the ribboned layers of a fresh-water deposit (the Purbeck beds, for instance). 

 The planes of division contain much mica. The formation of this loam is easily 

 explained, by conceiving icebergs to have stranded upon the shoal of Chalk, 

 the margin of which extended to this place, and grinding over the surface under the 

 action of winds and tides, to have raised clouds of chalky mud, which, mingling 

 with the foreign material from the berg itself, settled at a lower level, in horizon- 

 tally bedded loam, around the confines of the shoal. 



The deep channels cut out of the chalk surface by these bergs, are to be found 

 further to the west. There is a splendid section of such a one in the railway cut- 

 ting between Holkham and Wells. The width of it is 120 yards. It is filled with 

 coarse bouldered gravel, and fine calcareous sand, containing abundantly frag- 

 ments of chalk foraminiferae, and occasionally a fragment of the Cardiiim edule. 



a b c a 



Railway Cutting west of Wells, Norfolk. Length 100 yards, height 25 leet. 



a. a. Chalk in situ. 



b. False bedded calcareous white sand, consisting largely of minute organisms of the Chalk 



with an occasional fragment of Cardiuiit edtde. 



c. Very coarse bouldered flint gravel, with subangular lumps of Chalk. 



1 Mr. Seeley considers it to be probably Ostrea acutirostris (Nills), common in the lower 

 Chalk of Camt)ridgeshire. 



* There is reason to think that this disintegration is sometimes very old, if not Pre-glacial and 

 of the age of the Forest bed, owing to the remarkable cervine remains accompanying it, as at 

 Whitlingham, 



