Gault stufe 



(Albien D'ORB.) 



112 MIDDLE ALBIAN STRATIGRAPHY 



Kilian (1907 ; 62, 67) presented the following scheme influenced probably by the 

 work of his pupil Jacob. 



4 Zone der Schloenbachia (Mortoniceras) inflata Sow. sp. 



(mit zwei Subzonen) 

 3 Zone des Hoplites dentatus Sow. sp. und Acanthoceras 



lyelli Leym. sp. 

 2 Zone des Hoplites tardefurcatus Leym. sp. und Hoplites 



regularis Brongn. sp. 

 1 Zone des Parahoplites Nolani Seunes sp. (sog. 

 Milletianusschichten) und Douvilleiceras nodosoco- 

 statum D'ORB. sp., D. Bigoureti Seunes sp. 



For the first time Lyelliceras lyelli is used formally in a zonal scheme. Jacob's 

 thesis was completed in 1907 but not published until the following year (1908 ; 208- 

 590, pis. I-VI) when he presented the stratigraphical results of his study of the 

 middle part of the Cretaceous of the French Alps and adjoining regions. He divided 

 the Albian into the four zones which appear in Kilian's work but in a simplified form. 

 His scheme is as follows (1908 ; 296). 



VIb Sous-Zone a Mortoniceras inflatum Sow. sp. 



et Turrilites bergeri Brong. 

 Via Sous-Zone a Mortoniceras hugardianum d'Orb. sp. 

 V Zone a Hoplites dentatus Sow. sp. 

 IV Zone a Hoplites (Leymeriella) tardefurcatus Leym. sp. 

 Ill Zone a Douvilleiceras nodosocostatum d'Orb. sp. et 



Douv. Bigoureti Seunes sp. 



The Clansayes horizon (Kilian's Zone 1, Jacob's Zone III) is, therefore, added to the 

 Albian. Jacob could not accept Barrois' zone a Ammonites mammillaris because he 

 considered that this form was equally abundant in the following horizon (i.e dentatus 

 = interruptus Zone), mistaking forms such as Douvilleiceras clementinum (d'Orbigny) 

 for ' Ammonites mammillaris '. So, he renamed the zone ' Zone IV a Hoplites 

 {Leymeriella) tardefurcatus ' (= Zone of Hoplites tardefurcatus and Hoplites regularis 

 in Kilian) . Kilian and Jacob correct the specific name of the interruptus zone to that 

 of dentatus, but Jacob does not adopt the index Acanthoceras lyelli. When revising 

 the section at Sainte Croix, Vaud, Switzerland, Jacob indicates (1908 ; 291) that 

 Zone IV = l'Albien inferieur, V = l'Albien moyen, and VIb = l'Albien superieur of 

 Pictet & Campiche (1858). 



Jacob seems to have misread Jukes-Browne (1900) for it was not the term Gault 

 that Jukes-Browne could not accept, but the term Albian in the sense of Barrois 

 (Jacob 1908 ; 584). The re-inclusion of the Zone a Ammonites inflatus of Barrois 

 (Kilian's Zone 4, Jacob's Zone VI) in the Albian, a return to d'Orbigny's original 

 definition in terms of lithology, removed the cause of Jukes-Browne's objection to the 

 term Albian. Neither Jacob nor Kilian accepted or even mentioned Jukes-Browne's 

 Zone of Ammonites lautus. This is understandable when one considers that they 

 were strongly influenced by the succession in the Aube (1908 ; 547), with which Price 

 & Delatour had given a completely inaccurate correlation of the beds at Folkestone 



