44:4 Geological Society : — 



'6. " The Upper Eocene, comprising the Barton and Upper Bag- 

 shot Formations." By J. Starkie Gardner, Esq., F.G.S., and Henry 

 Keeping, Esq.; with an Appendix by H. W. Monckton, Esq., E.ti.S. 



The familiar Upper Eocene having been transferred to the Oligo- 

 cene, the remaining uppermost division of the Eocene bears the title 

 Middle. Unless the considerable literature relating to the Brackles- 

 hams, the Calcaire Grossier, and the Nummulitie, is to be rendered 

 obsolete, their classification as Middle Eocene must be preserved, and 

 a modified Upper Eocene constructed out of the Barton series. The 

 authors' proposal is that the following should be adopted : — 



London Area. Hampshire Area. 



Upper Barton. 



Middle „ 



Upper Bagshot Sands. Lower „ 



The base of the formation is not sharply defined, but it coincides 

 with the final disappearance of several subtropical Mollusca, and 

 almost with the extinction of Nummulites in our area. The upper 

 limit is drawn at the base of the Lower Headon, where the brackish 

 fauna gives place to one of fresh water. 



The conditions of deposition were examined at some length, and evi- 

 dence in support of the estuarine origin of the formation was adduced. 

 The section in Christchurch Bay was described first, and the thickness 

 and characteristics of each subdivision given, the total reaching 170 

 to 180 feet. It commences with 45 feet of whitish sand, and in 

 ascending order, a pebble-bed, 11 feet of greenish clay, and a band 

 of imperfect ironstone underlying the zone of Nummulites elegant. 

 Then 20 feet of stiff drab clay, 13 feet of drab clay with sand-drifts, 

 and 12 feet of the same, known as the Highcliff Sands. The Lower 

 Barton terminates with the Pholadomy a '-bed. The fauna of this 

 division comprises many Bracklesham species, which range no farther 

 up, and a large number of peculiar species. The most convenient 

 base-line for the Middle Barton is the lowest of several bands of 

 Septaria, which distinguish the 50 feet of drab clays which are com- 

 prised in it, and it terminates in a very remarkable formation known 

 as the shell-bed, which though only a foot or two thick at Highcliff, 

 thickens to about 15 feet to the east, and to 22 feet in the new 

 Christchurch cutting. The finest Barton fossils are obtained from 

 the Middle division ; but though so many splendid species charac- 

 terize it, few are absolutely confined to it. The upward range of 

 a further number of Bracklesham species ceases at the shell-bed. 

 The Upper Barton includes the Chama-hcd, the Bccton Bunny and 

 the Long Mead End beds. 



The Becton Bunny beds, 52 ft. thick, are sand in the lower half 

 and sandy clay above — Oliva Branderi is the characteristic fossil, 

 and a large number of bivalves and brackish Headon Gasteropods 

 come in. Opinions have differed considerably as to whether these 

 beds should be included in the Bartons. The series closes with tho 

 Long-Mead-End Sands, 20 ft. thick, with similar fossils, and for- 

 merly known as the Upper Bagshot Sands of the Hampshire baaa. 

 The section is continued without any break into the Lower Headon. 



