Dr. FiTTON on the Strata below the Chalk. 



311 



Diss, on the confines of Norfolk and Suffolk*, about five-and-twenty miles east of Mildenhall ; 

 tlirouirli which place if a line were drawn on the line of dip, it would pass nearly through Down- 

 ham on the margin of the Fens. In this section, the entire thickness of the chalk was cut through, 

 and combining it with that at Mildenhall, the result stands thus ; — subject, however, to some un- 

 certainty, from the imperfect condition of the specimens brought up in boring. 



Diss. 



a. Clay 



b. Sand 



Chalk. 



a. Without flints, soft, marly . 



b. With flints, in layers about \ 



a yard from each other . J 



c. Grey,with occasional layers! 



of white : no flints J 



d. Light bright blue chalk, "i 



approaching to clay, with >■ 

 white chalk stones .... J 



[On penetrating the light blue clay, 

 the boring-rods sank rapidly, and wa- 

 ter rose to within 47 feet of the sur- 

 face.] 

 . Sand ; — characters not stated 



50 

 50 



100 

 330 



60 



20 



Feet. 



100 



510 



615 



Mildenhall. 



I. Sandy loam 



Feet. 

 1 



II. Chalk. 



a. White, without flints . . 35 



b. Yellowish, gritty 5 



c. Grey, hard 136 



III. a. Blue clay 



b. Ditto, darker and harder 



c. Ditto, mixed with green 1 



sand J 



54 

 10 



10 



176 



74 



IV. Green sand, with many fossils .... 



V, Blue clay, abounding in fragments of"! 

 large shells, having a high polish . . J 



[Water coming in here, the work 

 was discontinued.] 



250 

 11 



9 



270 



The section at Diss is valuable, as it cuts through the entire thickness of the chalk, which is 

 here 510 feet; of which, it will be remarked, the uppermost 100 feet are marly and without 

 flints. The light blue stratum, 2. d, referred by Mr. Rose to the Gault, may, perhaps, rather 

 correspond to the lower portion of the chalk-marl, and to part of III. in the Mildenhall section ; 

 in which case 3. at Diss would represent the Upper green-sand. V. at Mildenhall is distinctly 

 referred by Sir H. Bunbury to the Gault, which he supposes to occupy the flat surface of the ad- 

 jacent fen. 



Mr. Rose states that the chalk range in West Norfolk dips to the south-east, about five yards 

 in a mile; or about 1 in 350. He has requested me to mention that he considers the estimate of 

 the heights given in his paper as probably exceeding the truth ; and at my suggestion, derived 

 from the levels in Cambridgeshire, he has reduced the altitudes in the section, PI. X. a. No. 25. 



The upper chalk of Norfolk includes the usual flint nodules ; and among the larger flinty 

 masses are some like those described by Dr. Buckland, under the name of Paramoudra. Many 

 of the fossils of the uppermost strata, according to Mr, Woodward, are different from those of 

 what he has called the medial chalk, which also contains flints. Near Swaffham, the chalk 

 without flints, which seems to belong to some intermediate beds between the upper and lower 



* Proceedings of the Geol. Soc. (1 833-4), vol. ii. p. 93. 

 VOL. IV. SECOND SERIES. 2 S 



