LOWER rERTIARY. 



»6S 



known as the zone of Osfrea bdlovacina, and 

 Pectunculus Urebratularis. Ascending the Thames 

 these beds are at first marine sands, differing but 

 little from the Thanet Sands. At Upnor, near 

 Rochester, they become estuarine, and consist 

 A layers of rounded pebbles and alternations of 

 mds and shell beds. This condition con- 

 tinues up the Thames valley, and the marine 

 shells, which were y distinguishable from 



the shells of the Thanet Sands at Heme Bay, 

 sh-water shells under London. 

 At Loampit Hill re- 

 mains of tern 

 plants and ins 



r. At Reading 

 i 

 matted leaves, 



to B] 



laurel and al 



ik, in the 

 r part ofthesands. 



which 



med in 



with 

 g ma- 

 rine shells which have 

 a Ion in time, 



some on tuning in the 

 Montian beds and sur- 

 viving to the London clay. It is therefore shown 

 by these Woolwich and Reading beds and their 

 »Slls that the dome of the Wealden district, be- 

 tween the Thames and the English Channel, was 

 raised into land; and that the chalk which once 

 covered it furnished the flints which were rolled 

 into completely rounded pebbles before they were 



na, from 

 the The shell has 



grown en a branch of a tree. 



