The YOtfHG HAT0BAMST: 



A Monthly Magazine of Natural History. 



Part 99. 



MABCH, 1888. 



Vol. 9. 



NOTES ON THE EOCENE FORMATION. 



By GEO. E. EAST, Junr. 



HE Eocene Formation is divided into three divisions or sections, viz., 



i. the Upper, Middle and Lower. The Upper or Oligocene comprises the 

 Hempstead, Bembridge, Headon, and Brockenhurst beds. The Middle the 

 Barton, upper and lower Bagshot, and Bracklesham beds ; while the Lower 

 comprises the London Clay, Bognor, Woolwich and Reading beds, and 

 Thanet Sands. 



In these notes it is proposed to make a few brief remarks on the Upper or 

 Oligocene beds. 



These beds occur at Hempstead, about 1| miles to the east of Yarmouth, 

 Isle of Wight. They consist of a series of Clays and Marls, and are grouped 

 into several distinct sections. At Hempstead, the highest strata is composed 

 of a bed of sand grey or bluish grey weathering yellow, and containing con- 

 cretionary portions consisting of fragments of shells, often enveloping the 

 entire shells of Ostrea callifera, a very large species. This bed passes into a 

 greenish clay, with numerous well preserved Corbula, and is followed by 

 clay of a bluish hue, and more or less interrupted by a belt of large septaria, 

 pale grey in the fracture weathering ferruginous, and often studded with 

 finely preserved shells of Corbulce and Cerithium subcostellatum ; and at the 

 base of this clay bed there is a variable thickness, more shaly, and very full 

 of Corbulce of a different species. These foregoing beds may be regarded as 

 of marine or salt-water origin, and as constituting the uppermost division of 

 the Hempstead series. The next bed is of brownish carbonaceous, more or 

 less laminated clay, containing fresh- water shells,, this is followed by a lead- 

 coloured clay, then a fresh-water bed again recurs, containing pale blue and 

 very tanacious clay, and in places carbonaceous bands. At the base of this 



The Hempstead Beds. 



