G. F. Harris — Geology of the Gironde. 23 



basin, which are on about the same level as our Woolwich and 

 Heading series. Following on above these in a well-boring in 

 Blaye, sands and sandstones occur containing Nummulites planulata, 

 var. (aplatie), believed by M. Benoist to be the equivalents of the 

 Sables de Cuise of the Paris basin, on about the same horizon as the 

 uppermost part of the London Clay and the Lower Bagshot beds 

 (London sands) of the London basin. 



It is noteworthy that if M. Benoist's classification is correct, the 

 general succession of the Lower Eocenes of the Gironde is not 

 very different to that of the south of Belgium and northern por- 

 tions of the Paris basin, except that the equivalents of the Thanet 

 sand are missing in the Bordeaux district. Even the lignitic 

 character of the analogues of the Woolwich and Reading series is 

 persistent. 



M. Fallot, however, is of opinion that M. Benoist is rather too 

 sanguine about the evidence obtainable from the well-borings. He 

 regards 1 most of the conclusions as to correlative age as hypo- 

 thetical, although he admits that just outside the Department, near 

 Saint-Palais (Charente-Inferieure), the equivalents of the Sables de 

 Cuise are found. He raises a question as to whether the Nummulites 

 are correctly determined. 



There is no doubt whatever that Middle Eocene beds are found in 

 the Gironde. The lower portions termed " Couches a Nummulites" 

 mostly sands and sandstones, are found only in well-borings. The 

 lowermost Eocene bed cropping out at the surface is the Calcaire 

 Grossier, and both the upper and the lower divisions of this formation 

 occur with characteristic fossils such as Strombus omatus, Potamides 

 angulosus, P. tricarinatus, and Delphinula conica, at Blaye. The Cal- 

 caire Grossier is approximately equivalent to our Bracklesham beds. 

 Above these come the (i Bartonien " series of clays, marls and 

 lacustrine limestones, characterized by the usual Ostrea cucullaris, 

 Limnea longiscata, Planorbis rotundatus, etc. The lower portion of 

 the series corresponds to the " Sables de Beauchamp " (part of the 

 Sables Moyens) of the Paris basin, or in part to our Barton beds ; 

 and the upper to the "Calcaire de Saint-Ouen " or our Upper 

 Bagshot sands. The Bartonien beds in the district under discussion 

 are found principally in the Blayais and the Medoc. 



The Upper Eocene (French classification) or " Ligurien " crops 

 out at various places in the northern half of the Department, more 

 especially in the Blayais, the Medoc, and near Saint-Vivien. This 

 subdivision of the Tertiaries in the Gironde is known also as the 

 " Calcaire marin de St.-Estephe." It is specially characterized by 

 Sismoudia occitnna, which occurs in great abundance. M. Benoist 

 has recognized 2 three horizons : — 



1. Upper zone with Clavagella Moulinsi. 



2. Middle zone with Echinoderms. 



3. Lower zone with Mdiolites and Orbitolites. 



i Esquisse Geol. du Dept. de la Gironde (Feuille des Jeunes Naturalistes, xix. an.), 

 1889, p. 5. 



a " Desc. des communes de St.-Estephe et de Vertheuil," p. 12. 



