582 MESSES. JUKES-BROWNE AND W. HILL ON" THE LOWER PART 



mass, and shell-fragments, which, often occur in small accumulations, 

 about 8 or 10 per cent, more, the remainder being fine amorphous 

 material. That part of the Gault above the hard beds, while still 

 containing fine inorganic material, abounds in shell-fragments, 

 Foraminifera, and calcareous atoms, the amount of -the coarser 

 fragments varying in different specimens. Recognizable particles 

 of quartz are few and small, and grains of glauconite have not 

 been detected at all. 



The pink marl of the cutting and of the brook presents no impor- 

 tant difference in structure from that described above. 



The yellow and red beds passed through in the boring at Der- 

 singham are alike in their structure. As in the Gault at Roydon, 

 especially in that lying above the hard beds, organic material 

 preponderates, single Foraminiferal cells, with some shell-fragments, 

 forming no inconsiderable part of their mass. A few large grains 

 of quartz-sand occur in the Red Clay, visible to the unassisted eye 

 and comparable with those from the Carstone ; smaller particles are 

 not uncommon. 



We have been unable to make a satisfactory section of the basal 

 foot of the Red Chalk at Hunstanton ; but above this the structure 

 is much the same as that of the most calcareous Gault above 

 described. Foraminiferal tests are perhaps in greater proportion, 

 and there are indications of sponge-structure in the specimens 

 examined. The upper part of the Red Chalk will, in fact, compare 

 with the Red Clay of the Dersingham boring, with the more cal- 

 careous specimens of the Grimston Gault, and also with the hard 

 beds, its chief difference being the greater amount of large quartz- 

 and other mineral grains which it contains, and which have 

 evidently been derived from the sands on which it lies. 



The Glauconitic Marl found at the base of the Chalk-marl at 

 Stoke Perry has many points of resemblance both to the Cambridge 

 Greensand and to the beds which lie at the base of the Chalk-marl 

 in Bedfordshire. It is a calcareous marl, containing an abundance 

 of glauconitic grains, with some mica-flakes and fine quartz-sand ; 

 and though these materials, particularly the glauconitic grains, are 

 smaller and finer than in the Greensands of Bedford or Cambridge, 

 the fact of their appearance in abundance at this horizon in a 

 locality where such inorganic material is rare is most important. 



The base of the Chalk-marl seen in the pit at Shouldham is a 

 glauconitic bed, similar in all respects to that above described. This 

 marl was again identified at Marham, beyond which it was lost. 

 Above this bed, at Shouldham, the Chalk-marl, though hard, is not 

 gritty, fine amorphous material forming a large proportion of its 

 mass ; single Foraminiferal cells are conspicuously abundant, and 

 these with a few shell-fragments and entire Foraininifera constitute 

 the remainder. 



Chalk-marl. — Following the Chalk-marl, as we have done the GauJt, 

 we find that at Charlton, in Bedfordshire, it consists of a bluish 

 grey clayey marl, with a recognizable amount of glauconitic grains, 

 fine quartz-sand, and a proportion of the fine inorganic matter 



