122 MESSES. A. J. JTIKES-BROWNE AND W. HILL: [May 1 896, 



It will be seen that the contrast between this fauna and that of 

 the beds below is very great. It is the incoming of an entirely 

 new set of fossils, and the presence of Stauronema Carteri is a strong 

 confirmation of the view which at once impressed itself upon us that 

 the bed corresponds to the Chloritic Marl of the Isle of Wight. 

 Almost all the brachiopoda and mollusca occur in our Chloiitic 

 Marl, though most of them occur also in the highest bed of the 

 Upper Greensand near Warminster, which is part of the so-called 

 * zone of Pecten asper.' The relations of this zone in England to the 

 French Cenomanian will be discussed in the sequel. 



What we desire to point out in the present connexion is that in 

 the cliffs near Havre there can be no question where the Cenomanian 

 fauna commences : that it comes in suddenly with a bed which 

 resembles our Chloritic Marl, both in its mineral composition and in 

 its fossil contents, and in its included phosphatic nodules. Above 

 this bed there is no break whatever, and, though the material of the 

 overlying beds is different from that of our Chalk Marl, these beds 

 pass up gradually into a true chalk near the top of the formation. 



Bed 6. 



At and near Cape La Heve the phosphate-bed is succeeded by beds 

 of soft marly and glauconitic chalk, divided by layers of a peculiar 

 kind of siliceous stone. Examination of this stone proves it to be 

 permeated and indurated with colloid silica, the condition of the 

 material being in every stage from merely hardened chalk to a blue- 

 grey siliceous mass, like the immature chert occurring in the Chalk 

 Marl of Wiltshire, and described by us, 1 while here and there it is 

 concentrated into nuclei of pure crystalline silica. The result at 

 this horizon is not definite chert or flint, but ramifying masses of 

 siliceous material, passing in places to clear black or grey -coloured 

 chert or flint, without any definite rind. 



These beds are discontinuous, and there is a good deal of variation 

 in the succession of chalk and chert, even in sections a short dis- 

 tance apart. 



Between these hard beds the chalk is soft and marly, sometimes 

 firm, but it always contains much glauconite in grains of rather 

 small size compared with those of the Chloritic Marl. The hard 

 beds gradually become less marked, and separated nodules or beds 

 of chert begin to appear. 



The incoming of the cherts at La Heve is marked by five courses 

 of exceptionally massive character, and these form a striking feature 

 in- the cliff-face. A little east of the lighthouses the lowest line is 

 34 feet above the base of the Chloritic Marl, but nearer Havre it is 

 only 27 feet 6 inches above it. 



Above and between these cherts to the top of Bed 6 the chalk is 

 of a pale yellowish-white colour, firm in character, and rather 



1 Quart. Journ. GeoLSoc. vol. xlv. (1889) p. 403. 



