202 



T, Davidson — On Continental Geology. 



has made the " Cretaceous system " a subject of particular study. 

 M. Hebert considers that M. Coquand has separated the period into 

 too many definite divisions (etages), and in two papers published in 

 the Bulletin of the Geological Society of France (vol. 16 and 20, 2nd 

 series), his views upon that topic have been fully recorded. He had 

 not, however, drawn up any complete scheme of classification, but this 

 he has now kindly done at my request. (See Table of Classification.) 



The same gentleman justly insists that it is impossible to ascertain 

 the absolute value of the divisions by the characters which they may 

 exhibit in a single region ; that the Chalk with Belemnites so spar- 

 ingly represented throughout Western Europe, would appear on the 

 contrary to cover in the East immense surfaces, and the Upper 

 Chalk, though reduced to a few spots throughout the whole of Europe, 

 assumes in America and India a considerable extension. 



Monsieur Cornuel has likewise devoted considerable attention to the 

 divisions of the Cretaceous system, and has kindly furnished me with the 

 following statement, with reference to various classifications applied to 

 the same group by himself, and Messrs. Leymerie, d'Archiac, Eene- 

 vier, and Hebert. He still adheres, however, to the classification 

 proposed by himself in 1860, and does not approve of the alterations 

 introduced by M. Hebert in his paper published in the twenty- 

 fourth volume, p. 379, Feb. 1867, of the Bulletin of the Geological 

 Society of France. 



Division of the Lower Cretaceous Formation in the Department of the 

 Haute-Marne, by M. Cornuel. (Bulletin of the Geol. Society of France, 

 2nd Series, vol. xvii., p. 742. 1860). 



16. Gault. 

 15. Green sand. 



14. Sand and yellowisli sandstone. 

 C (-upper. 



j 13 Clay with P?zca<«?^ > j^^jg_ 

 (. (argiies a rlicatulesj. J 



C (flower (Brachiopoda). 



1 12. Eed bed. 

 11. Oolitic iron. 



10. Sand and upper ferruginous sandstone. 

 9. Bose-eoloured variegated clay. 

 8. Spotted sands and sandstone. 

 7. Clays with oysters ( upper, 

 (argiies ostreenne) \ lower. 

 6. Yellow argillaceous marl. 



C Limestone with Spatanffusl^^j^.^^^^ 

 I Blue calcareous marls 3 Jr / 



4. White Sand. 



3. Sand and lower ferruginous sandstone. 

 2. Iron in rounded masses (Fer Geodique). 

 (^ I. 1. Blackish argillaceous marl (Brachiopoda). 



Each of these beds have been described by M. Cornuel in the 

 Memoirs of the Geol. Soc. of France (1 series, vol. iv., p. 230), but 

 the references to the fossils are not correct, and have been replaced 

 by others in the 8th vol., 2nd series of the Bulletin of the same 

 Society (p. 430). M. Cornuel has added to his paper published in 

 1860, a notice on the connections existing between the country of 

 Bray and the Isle of Wight (Bull. 2 series, vol. xix., p. 975) ; and, 

 in another communication, he assigns the limits of the two stages 



Pi ^ 

 CD 



2nd Stage or 

 Aptien. 



r 



Sub-division 



Upper 

 Neocomien 

 (Urgonien). 



Sub-division 



Lower 

 Neoeomien. 



r 



2nd 

 bed. 



1st 

 bed. 



2nd 

 bed. 



1st 

 bed. 



2nd 

 bed. 



1st 

 bed. 



