172 Merieus — Lemoine's Geologie du Bassin de Paris. 



phosphatic nodules of considerable economic importance ; the higher 

 strata consist of clays and alternations of sands, marls, and clays 

 {argiles du Gault). The Albian reposes on different formations from 

 older Cretaceous to various Jurassic divisions. 



In the Cenomanian further overlap took place, and it rests in places 

 directly on the Palaeozoic. 



Remarks are made on the difficulty in fixing divisions in the Chalk 

 of the Paris Basin, not merely on account of lithological changes, but 

 owing apparently to the presence of similar species of fossils at different 

 levels. 



The Cenomanian consists in places of glauconitic sands with Pecten 

 asper (found also in Albian), and with phosphatic nodules worked in 

 Marne. Higher beds consist of grey marls and marly limestones 

 with Solaster suhglohosns and Acanthoceras rotomagense. The passage- 

 beds between Cenomanian and Turonian are formed bj' the white 

 and nodular marl with Belemnites plains. Rhynchonella Cuvieri occurs 

 in the higher part of the Lower Turonian, and Inoceratmis labiatus is 

 found (rarely) in the Upper Turonian with the so-called Terelratulina 

 gracilis ; higher up in the series Holaster planus and Micrasler 

 breviporus are met with. Marstipites ornatus is recorded from the 

 highest part of the Emscherian, and Bourgtieticrinus ellipticiis from 

 the base of the Aturian, which contains both Belemnitella mucronata 

 and B. quadrata. A full account, with analyses, is given of the 

 phosphatic chalk worked in the zone of B. quadrata in Picardy. 



It is remarked that chalky conditions continued to exist in northern 

 regions, and notably in Belgium, after they had ceased in France, 

 where no representatives of the Chalk of Spiennes and Ciply are met 

 with. The Chalk of Meudon and Epernay, with Micraster Brongniarti 

 and Ostrea vesicidaris, is grouped with the Aturian or uppermost part 

 of the Senonian. With regard to the Montian division it is stated, on 

 the authority of Munier-Chalmas, that the lower portion is characterized 

 by Senonian and Danian forms of life ; the upper portion contains the 

 tj'pical Montian fauna. This fauna, of an age between Cretaceous and 

 Tertiary, includes Naidilus da^iiais, large forms of Cerithium, Cidaris 

 Tomheclci, C. distincta, etc. The deposits have been termed ' Calcaire 

 pisolitique ',' but the grains were due to calcareous algae. Towards 

 the upper part of the Chalk of Meudon there are indications of the 

 roots of plants beneath the pisolitic bed. Evidence of overlap of this 

 higher bed are noted ; it rests on the Emscherian Chalk in the valley 

 of the Mauldre, Montainville. 



Some remarks are made on the Clay-with-flints {Argile A Silex), 

 which is of different ages, in part post- Pliocene. 



The nomenclature adopted for the ages of the Tertiary formations is 

 as follows : — 



PLIOCENE. 



Sicilian Sables de St. Prest. 



Plaisancian .... Couches du Boscq d'Aubigny. 



PONTIAN Couches a Cardita striatissima. 



Sarmatian .... Conglomerat de Gourbesville. 



^ In the table, p. 132, both Danian and Montian are grouped as ' Calcaire 

 pisolitique ', and placed above the Senonian. 



