INTRODUCIION. 



of this East Torkshire formation with Wealden rooks of North- 

 West Germany, England, and Worth France is expressed in 

 tabular form as follows ' : — 



FOUR ZONES or SPEETON CLAY. 



N.W. Geemaijt. 



Hils beds with Crioceras Emerici, etc., etc. 



Hils clay with Soplites regalis, etc., etc. 



Upper Portlandian, brackish 

 or Purbeckian type 

 ("Wealden of German geo- 

 logists) . 



Hils grit and con- 

 glomerate with 

 Selemnites lateralis, 

 etc. 



Serpulite 

 Miinder Mergel 



S. England and 

 Boulogne. 



Weald clay. 

 Hastings sands. 



Upper Portlandian, 

 brackish or Pur- 

 beckian type. 



In another recent work, "Text Book of Comparative Geology," 

 by Kayser (translated and edited by Lake), we find this extremely 



WEALDEN. 



simple table in which the term "Wealden is used in the wider sense.* 



Having thus defined the term "Wealden as employed by some of 



the most recent writers, and stated the sense in which it is used 



^ Arg. Speeton, pp. 200-201. 

 ' p. 288. 



