CHAP. XI.] HANTONIAN PEBIOD. 205 



but beds of the Bagshot type are in great force at Stud- 

 land Bay and Corfe. 



Layers of pipeclay containing plant remains are present 

 in the Lower Bagshot Beds, but are thicker in Dorset than 

 they are in the London basin. As such clays have generally 

 originated from the decomposition of granitic rocks, and 

 as such rocks occur to the westward, in Devon and Corn- 

 wall, we may take it as very probable that the materials 

 both of the clays and sands came from the south-west. 



The geographical changes which seem to have taken 

 place during the Eocene period cannot be properly under- 

 stood without a study of the deposits in the Paris basin. 

 In this area the Lower Eocenes are but feebly developed. 

 The Sands of St. Omer and Douai, which correspond to our 

 Thanet Sands, do not extend into the Paris basin, and as 

 there is no equivalent of our London Clay, the whole series 

 is represented near Paris by beds which are similar to our 

 Woolwich and Eeading group. For the following details 

 of the succession at Yaugirard, I am indebted to Mr. J. S. 

 G-ardner : 



Feet. 



Base of Calcaire Grossier . . . . . 



Lower f ~^ ue c ^ avs and san( l s > ^h lignite . . 20 



Eocene. ) Mottled P lastic cla 7 . . 13 



I White marl with freshwater fossils . .16 



Calcaire pisolitique (Cretaceous) . . . .10 



Here the lignitic group is directly succeeded by the 

 representative of the Bracklesham, but elsewhere there are 

 sands (Sables de Cuise) which contain marine fossils, and 

 are probably about the age of the Lower Bagshot Beds. 

 Moreover, an outlier of London Clay occurs at Dieppe, so 



Society, and has proposed that the Lower Bagshot should henceforth be 

 called the Londou Sands, but it may be questioned whether it would 

 not be better to retain the name of Bagshot for the lower, and to change 

 the designation of the middle and upper beds. 



