OP THE SWISS JURA AXD ENGLAND, 



233 



dian beds lie are known as ' Combes Oxfordiennes.' The rocks 

 of this stage are divisible into : — 



2. Le Terrain a chailles marno-calcaire. 

 1. Le Calcaire a Scyphies infe'rieur *. 



In the northern part of the Jura, the lower part of the Oxfordian 

 is seen overlying the Marries a fossiles pyriteux as a grey or black 

 clay, fairly fossiliferons. The typical locality for this substage is 

 Hobel, south of Basle, and G-reppin gives a list of fossils from this 

 place (pp. cit. p. 63). 



The Terrain a chailles marno-calcaire is composed of yellowish- 

 grey clays, alternating with limestones of the same colour, and con- 

 taining sphe rites or chailles. 



In the gorge at Thiergarten, near D element, the upper Jurassics 

 are cut through, and here, underlying the 'Terrain a chailles silicenx,' 

 about 110 feet of Oxfordian are exposed, consisting of alternations 

 of bluish clays and limestones. 



They are also seen in the quarry south-east of Liesberg (see section 

 fig. 1, p. 231) as yellowish limestone separated by sandy clays of 

 the same colour, passing up into bluish clays with thin limestones. 

 Similar beds also crop out below the 4 Terrain a chailles siliceux,' 

 south of St. Ursanne station. 



In the ' Combe Chavatte,' the Oxfordian is from 100 to 130 feet 

 thick, and consists of bluish marly clays with intermediate beds of 

 limestone ; some of the latter are fairly thick and regular, whilst 

 others are nodular. These beds are seen lying between the Clay with 

 pyritous fossils and the ' Terrain a chailles siliceux,' and these 

 yielded the following fossils : — 



Pholadornya exaltata, Ag. 

 paucicosta, Ag. 



Pleuroinya yarians. Ag. 

 Rhynchonella Thurnianni, Voltz. 



Further south, at Paturale and Le Cernil (north of Tramelan), 

 above the Clays with pyritous fossils, come grey marly beds con- 

 taining nodules of impure limestones, from which the following 

 fossils were obtained : — 



Ammonites cordatus, Sow. 



convolutus, Querist . 



sulciferus, Opp. 



hecticus, Rein. 



perarmatus, Sow. 



Pleurotomaria Munsteri, Bom. 

 Astarte robusta, Lyc. 

 Modiola bipartite, Sow. 



Trigonia perlata, Ag. 

 Lima subautiquata, Rom. 



duplicate, Sow. 



Pholadornya exaltata, Ag. 



concinna, Ag. 



Terebratula insignia, Schub. 

 bisuffarcinata, Schl. 



The Corallian has been divided by Thurmann into three sub- 

 stages, and this classification is adopted by Greppin : — 



3. Le Calcaire a Xerinees. 



2. Oolithe Corallienne. 



1. Terrain a chailles siliceux f. 



* Greppin, in his ' Essai ' &c, includes this substage in the i Callovien.' 

 t Greppin. in 1867, included this in the ' Oxfordien.' 



I J. G. S. IS T o. 170. b 



