OP THE UPPEB CEETACEOES EN" WEST SEEEOEK AXE NORFOLK. 581 



examination of cores from a boring near Tring showed that there 

 was a gradual passage extending through many feet from the coarse 

 material of the Greensand to the finer material of the Upper Gault, 

 a similar but more rapid passage to the Lower Greensand occurring 

 at its base. 



Proceeding along its outcrop to the north-east from Tring, the 

 upper part of the Gault becomes more calcareous, and contains many 

 Foraminifera, shell fragments and atoms of a calcareous nature, 

 rendering it at Fancourt, near Harrington, almost comparable to 

 certain parts of the Chalk-marl. But it is invariably separated 

 from this formation by a Glauconitic Marl, a bed in which rather 

 coarse grains of glauconite, quartz and mica flakes, with many shell- 

 fragments, abound in a calcareous matrix, though the amount of 

 its several ingredients varies somewhat with locality. 



Proceeding still further to the jST.E., we reach the incoming of 

 the Cambridge Greensand dividing the Gault from the Chalk-marl, a 

 bed marked by the abundance of large glauconitic grains, rather 

 coarse quartz-sand, and some mica. At Arlesey this bed rests 

 immediately on the Gault, which is not calcareous and agrees with 

 that from its centre near Tring, there being no passage whatever. 



We have .had no opportunity for the examination of the material 

 at the junction of the Gault and Cambridge Greensand between 

 this point and Stoke Ferry, but at Stoke our boring passed through 

 a bed in which green grains were abundant, and which also 

 contained quartz and mica, and then entered abruptly into bright 

 blue clay, which, though less calcareous than that at Fancourt, is 

 more so than at Arlesey, and is probably Upper rather than Middle 

 Gault. It forms a link between the latter and the still more 

 calcareous deposit which we recognize as the Upper Gault further 

 to the north-east. 



The Lower Gault exposed at Muzzle and West Dereham is some- 

 what calcareous and contains many shell-fragments, &c. ; it is. 

 however, not unlike that from the lower part of the Tring boring, 

 but there is a decrease of the coarser recognizable inorganic particles. 



The examination of specimens from the railway-cutting north of 

 Grimston station, from the brook sides, and from the boring at 

 Roydon pit shows that the deposit which we recognize as the Gault 

 has undergone considerable change. 



That lying below the hard beds, while still containing much of 

 the fine inorganic material, contains also a large proportion of shell- 

 fragments and Foraminifera, and calcareous atoms derived probably 

 from their decomposition. Glauconite appears to be absent, but 

 there are a few quartz-grains sparingly distributed through the 

 mass ; some of these appear to be of greater size than those usually 

 met with in the Central or Lower Gault, and may be derived in part 

 from the underlying sands. 



The hard beds seen both in the railway-cutting and elsewhere are 

 alike in their structure. They appear to be entirely organic, and con- 

 tain no quartz or glauconitic grains. Disunited or primordial cells 

 of Globigerina or other Foraminifera form nearly 20 per cent, of their 



