Vol. 52.] -A DELIMITATION OF THE CENOMANIAN. 133 



Turning towards Mortagne, along the high road, about J mile 

 from the village of La Jarretiere, the Greensand is exposed in a lane 

 to the left much as it is at Gace. Its character is the same, — a 

 light, calcareous, marly sand, passing down to a deposit almost black 

 in colour. The top is hidden ; a wide dark band, visible for 

 some distance away, betrays its outcrop in the arable fields, over 

 which are scattered fragments of the hard bed. The estimated 

 thickness of the Greensand here is 15 feet. 



The yellowish ' chalk ' with Ammonites Mantelli was seen to 

 immediately overlie the Greensand in the cutting of the road to 

 St. Hilaire les Montagne, about 100 yards nearer La Jarretiere. 



From the evidence gained by this traverse we think that after 

 leaving Cape La Heve a lateral change takes place at the base of the 

 Cenomanian ; that the bed with black phosphates dies out before 

 reaching Moulineaux, near Honfleur, and gives place to a bed con- 

 taining hard crystalline masses : that between Lisieux and Vimoutiers 

 this bed becomes condensed, as it were, until it forms- a small and 

 well-marked hard layer at the base of the ' Chalk.' If we are 

 correct in this opinion, this hard layer is the true base of the Ceno- 

 manian, and the beds below ought to be excluded from this stage. 



We have seen that the Gault at Lisieux is at the point of disap- 

 pearance, and consequently we take the mass of the glauconitic 

 sand south of that place to be the equivalent of the Gaize ; but, as 

 Pecten asper occurs in the sandy marls at the top of these, it would 

 appear that a local or lenticular deposit representing the English 

 zone of Pecten asper is ' present for some distance. Whether this 

 enters into the 10 feet of glauconite at Vimoutiers we will not 

 undertake to say, but we have no doubt that this 10-foot bed is 

 the attenuated representative of our Upper Greensand, and that 

 the beds above it are the equivalent of our Lower Chalk. 



[Note. November 7th, 1895. — Since the above was written we 

 find that Prof, de Lapparent has expressly separated this ' glauconie 

 a Ostrea vesiculosa ' of the Eure, Orne, and Maine from the Ce'noma- 

 nien (' Traite de Geologie,' 2nd ed. 1885, pp. 1041 and 1075). He 

 classes it with the Albien, and considers it to be the equivalent 

 of the Gaize of the Havre district ; speaking of the Cenomanian of 

 the Orne on p. 1075, he describes it as 'resting on the glauconie a 

 O. vesiculosa. ' This was a new departure, MM. Guillier, Bizet, and 

 other French geologists having always regarded it as the basement- 

 bed of the Cenomanian Series. It is satisfactory to find that we 

 had independently arrived at the same conclusion as M. de Lapparent, 

 and that, so far as Western France is concerned, we are in complete 

 accord with his definition of the Cenomanien stage. 



He does not venture upon any correlation of the western Ceno- 

 manien with English deposits, but includes the Warminster Green- 

 sand in his table of English equivalents. If, in his next edition, 

 he were to omit this greensand, his table would express precisely 

 our view of the subject.] 



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