EOCENE STRATA IN ENGLAND, BELGIUM, AND FRANCE. 



103 



clays and pebble-beds above and below. With the appearance of 

 the pebble-beds, false-bedding, indicative of the existence of strong 

 currents such as would be needed for the transport of these pebbles, 

 begins. It is this action which has in places removed so much of 

 the lower beds of the Woolwich series ; but this involves no real 

 unconformity, and I look upon these fossiliferous pebble-beds as 

 part of the Woolwich series. 



I felt originally some difficulty about this part of the series; 

 and my view of it may still admit of discussion on stratigraphical 

 grounds. It is, however, supported by the palaeontological evidence, 

 although, as so many species are common throughout all the divi- 

 sions of these Lower Tertiary beds, from the Thanet Sands upwards, 

 that evidence is not strongly marked. 



In the following list I have taken the fossils of the Basement-bed 

 of Hedgerley, Eeading, and other places about which there is no 

 question, together with the similar group of fossils from the bed in. 

 the Herne-Bay cliffs, marked in my section as the Basement-bed, 

 and named by Mr. Whitaker the " Oldhaven Bed," from the name of 

 the Gap, near Heme Bay, where it is best seen. The total number 

 of species amounts to 48, of which 23 are common to the Woolwich 

 beds and 30 to the London Clay. The Sundridge and associated 

 beds show, on the contrary, a much greater affinity with the fossils 

 of admitted Woolwich localities; thus, the list of the Sundridge 

 shells in the Survey ' Memoirs ' amounts to 51 species, of which only 

 16 are London-Clay species ; while the Ditrupa 'plana, Buccinum 

 jimceum, Cancellaria Iceviuscula. Oassidaria striata, Pyrula Smithii, 

 and other common London-Clay and Basement fossils are absent, and 

 we have, on the contrary, a profusion of Ostrea bellovacina, Peetun- 

 culus terehratularis, OeritJiium Bowerhanhii, Fusus latus, Melanopsis 

 huccinoides, Cyrena cuneiformis, O. tellinella, Modiola Mitclielli, and 

 other such common Woolvrich fossils. 



D. Shells of the Basement-bed, of the London Clay or Oldhaven Beds 

 (exclusive of the Sundridge species) and their range. 





Thanet 

 Sands, 



Woolwich 

 Beds. 



London 



Clay. 



AstartCj sp. 





* 



■ii- 



■«■ 



* 





plumsteadiense, Sby 





Corbula regiilbiensis, Morr 



Arnouldi, Nyst ? 



Oyprina Morrisii, 8by 



intermedia, Mell 



tellinella ?, Dcs^ 



Cy therea obliqua, Desk 





Carried forward 



3 



10 



5 





