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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 3, 



Perhaps the most striking variation is exhibited in the Wealden 

 beds, which, from a total thickness of 1200 or 1500 feet on the Kent 

 and Sussex coast, have dwindled away in the Boulonnais to 100 feet 

 or less. On the English coast the great division between Hastings 



Fig. 5. — Comparative Sections of Cretaceous Beds in Kent and the 

 Bas-Boulonnais. 



South-east of Kent. 



Bas-Boulonnais. 



Chalk 



Upper Greensand 



Gault 



Folkestone Beds.... i^^00^^ 



Sandgate Beds 



Chalk. 



Upper G-reensand. 

 Gault. 



Lower Greensand. 



Wealden. 



/ MoUuskite in places. 



Hythe Beds 



{ Atherfleld Clay 

 Weald Clay 



; X X Show horizons at which Phosphate of Lime is found. 



100 200 



Vertical scale I i i i | feet. 



Sand and Weald Clay is very marked, as also are the subordinate 

 divisions of the Hastings Sands ; but it is impossible to say what 

 part of our English series the Boulonnais beds represent. In the 

 quantity of mottled clays they resemble the Ashburnham beds, as 

 seen in the cliffs east of Hastings ; but such mottled clays are not 

 confined to any horizon in our Wealden beds. In the presence of 

 quantities of pebbles, some coarse and containing chalk-like frag- 

 ments, they resemble the top of the Hastings sands near Cuckfield ; 

 but similar conglomerates occur elsewhere and in other positions. 

 The absence, so far as is yet known, of Saurian remains, and the 

 comparative rarity of other fossils in the Boulonnais Wealden is a 

 notable distinction from the English beds. 



The constancy of the phosphatic bed at the base of the Gault is 

 worthy of note. It appears to be everywhere present around the 



