T. Davidson — On Continental Geology. 163 



improve or correct our system : at the same time carefully avoiding 

 the introduction of any foreign terminology on English ground until such 

 may have become a well-recognized and absolute necessity. 



With reference to the Cretaceous system and its divisons there 

 still remains in England ground for improvement, but I must at the 

 same time remind the English reader that the French, Swiss, and 

 G-erman geologists are far from unanimous in their terminology, or 

 as to the number or value of all their divisions. Very earnest discus- 

 sions are now in active progress between those who in France are 

 best qualified to express an opinion upon this difficult and important 

 topic. 



I will not enter here upon the general literature of the subject, 

 my object being simply to draw attention to the most recent views 

 entertained by continental geologists. It may however be desirable 

 for the better understanding of what will follow to mention at once 

 that the Cretaceous system in England has been divided in the fol- 

 lowino^ manner : 



1. 



Upper Chalk 



5. 



Upper Green Sand 



2. 



Lower Chalk 



6. 



Gault 



3. 



Chalk Marl 



7. 



Lower Green Sand 



4. 



Chloritic Marl 



8. 

 9. Wealden 



Neocomien 



and that it is mainly due to Mr. Judd's admirable labours on the 

 Speeton Clay, that the existence of a large portion of the Neocomien 

 formation in England has been recently established. Mr. Judd is 

 prepared to stand by the succession of beds which he described at 

 Speeton,^ admitting at the same time that their grouping is to a great 

 extent arbitrary, as there are no stratigraphical breaks, and that he 

 was guided by all he then knew of the character of the French and 

 Jura Neocomien especially, from d'Archiac and the Swiss geologists. 

 Mr. Judd would, however, be prepared to modify his classification 

 so soon as sufficient cause may be shown. I am happy to be able to 

 state also that foreign geologists have warmly acknowledged the 

 great value of Mr. Judd's researches and inductions. — The valuable 

 labours of Mr. C. J. A. Meyer, Prof. Morris, the Eev. T. Wiltshire, 

 Mr. J. F. Walker, and of some others,^ have also materially contri- 

 buted within the last few years towards clearing away some of those 

 difficulties which still beset the final settlement of our divisions. 



In France the old nomenclature was rejected by M. Alcide d'Or- 

 bigny, who divided the system into the following stages : 



1. Danien 5. Albien 



2. Senonien 6. Aptien 



3. Turonien 7. Urgonien 



4. Cenomanien 8. Neocomien. 



For many years M. Coquand, a very able and experienced geolo- 

 gist, has been devoting considerable attention to the Cretaceous 



1 Quart. Journ. Geol. Soc. for August, 1868. 



^ These papers will be found in the volumes of the Geological Magazine, the 

 Proceedings of the Geologists' Association, and the Quarterly Journal of the Geologi- 

 cal Society. 



