CRETACEOUS SEEIES IN LINCOLNSHIRE AND YORKSHIRE. 307 



Melbourn rock and Totternhoe Stone as zones for defining the posi- 

 tion of the intermediate Chalk. 



Mr. Strahan admitted the persistence of the Chalk-zones, and 

 said that when he worked in Lincolnshire it had not been possible 

 to go into these details. The only difference recognized was be- 

 tween Chalk with and Chalk without flints. The Eed Chalk con- 

 tains derived fossils as it is traced northwards. He inquired 

 whether Ammonites interruptus and Am. rostratus were indigenous or 

 derived. 



Mr. HuDLESTON said that the Author had earned the right to do 

 the work of correlation for the northern region from the share he 

 had taken in defining the very difficult beds in Norfolk and SuflPolk, 

 which constituted the key to the whole series of changes. As we 

 go further north, especially in Yorkshire, the fauna of these beds is 

 scanty ; yet Professor Blake had made the general correlation clear, 

 though, now we have the details. It was interesting to note with 

 regard to the Gault that its Cephalopoda sustained the proof of a 

 definite pala^ontological horizon, whether a blue marl in Bedford- 

 shire, a red chalk at Hunstanton, or a yellow conglomeratic bed, as 

 at Wharram. If Ammonites are scarce, Belemnites minimus never 

 fails us. On the other hand, the rest of the fossils at Speeton and 

 elsewhere in Yorkshire are mostly Cenomanian, like those of the beds 

 above. The red coloration must have been effected after the decom- 

 position of all the organic matter in the bed so coloured, and this 

 seems to point to subsequent infiltration. 



Mr. Herries inquired if there was any representative of the Upper 

 Greensand at Speeton. How did the Author account for the colour- 

 bands extending for such a long distance ? 



Mr. Newton corroborated the identification of Amm. interruptus 

 and Amm. rostratus as occurring in the Ked Chalk. 



Mr. De Eance suggested that Amm. interruj^tus, a Lower-Gault 

 form, might have been derived. 



The Author, in reply, thanked the meeting for the reception 

 accorded to his paper. The specimen of Amm. interruptus had beeii 

 found in the lower third, and that of Amm. rostratus about the top of 

 the Red Chalk. There was no sign of Greensand at Speeton ; the 

 beds there became more calcareous above the Hunstanton Limestone. 

 He allowed that the key of the whole position had been found in 

 the study of these beds between Cambridge and Hunstanton, and 

 he also acknowledged the value of the work done by others. He 

 had endeavoured to simplify inatters by bringing the facts together. 



Q. J. G. S. No. 175. 2 c 



