552 MESSES. JUKES-BE0WNE AND W. HTLL ON THE LOWEE PAET 



above the base of the Gault * ; but in both the brook-sections soft 

 greyish-blue marl underlies the lower hard bed, below the outcrop of 

 which the banks weather down, and the strata through which the 

 water cuts its way are no longer openly exposed. 



A small exposure was noted of grey clayey marl, with some pinkish 

 streaks, just to the east of the gardens at Sandringham, in what 

 appeared to have been an old pit close by the road. This we refer 

 to the Gault. At a subsequent visit this exposure was covered up, 

 but red clayey earth was seen just above the outcrop of the Carstone 

 around some young trees which had just been planted. 



That which we believe to be the final thinning-out of the Gault 

 clay was found by boring in the large chalk-pit at Dersingham (for 

 section see p. 560). Here, below the hard Chalk-marl, 2 feet of 

 softish pale grey marl was found, and beneath this 3 feet of 

 yellowish-brown chalky material, hard at the top, but passing down 

 into 2^ feet of red marly clay, which rested immediately on the 

 Carstone. 



This confirms a statement of the Rev. T. Wiltshire, who says -j* : — 

 " According to the statements of persons resident in the district 

 adjoining Hunstanton, and who have seen inland sections opened 

 for agricultural purposes, the blue Gault, with its characteristic 

 Belemnite, rests on the Carstone at Plitcham, 10 miles south of 

 Hunstanton ; but rather nearer the latter place, and still close to 

 Plitcham, a red clay occurs immediately under the White Chalk, 

 thus connecting the blue Gault with the Red Chalk." 



As will be seen in the sequel, the stratigraphical evidence is 

 strongly in favour of the Red Chalk being the actual continuation 

 of the Norfolk Gault, a conclusion which agrees with that arrived 

 at by Mr. Wiltshire ; but it will be seen that the strength of this 

 evidence lies in the identification of the overlying " sponge-bed" as 

 the real base of the Chalk-marl. 



B. The Clialk-marl and Totternhoe /Stone. 



The thickness of the Chalk-marl in Cambridgeshire is from 60 to 

 70 feet, and its upper beds, underlying the Totternhoe Stone, are well 

 exposed in the large quarry at Reach and in the northernmost 

 quarry at Burwell. 



At Reach a face of about 30 feet is seen, the highest beds being 

 tough and blocky, drying to a dull greyish white and being then 

 fairly compact ; they are not really bedded, but split into large blocks 

 with curved and largely conchoidal fractures, and the whole mass 

 is divided by strong joints ; this " clunch," as it is locally called, 

 passes down to a softer and darker brownish-grey marl which 

 towards the bottom of the section shades into a bluish shaly marl, 

 these lower beds containing Inoceramus lotus, Ammonites varians, 

 and other fossils in some abundance. 



The lower part of the Chalk-marl, as seen in the numerous 



* Phil. Mag. 1835, vol. vii. p. 180. 



t Quart. Journ. Greol. Soc. vol. xxv. p. 190. 



