viii PREFACE. 



the Upware bed in the Upper Neocomian or Aptien series (Lower 

 Greensand) 1 . There is however some difference of detail between 

 my results and those of Mr Teall. I refer them to a somewhat 

 lower horizon of the Lower Greensand than does Mr Teall, believ- 

 ing them to be of the age of Sandgate and Hythe beds with the 

 lower part of the Folkestone series (Meyer). This distinction 

 becomes important when we take into consideration the views of 

 some Geologists as to the relation of these beds to the superposed 

 series ; for the beds which are known as Upper Folkestone, the 

 mammillaris zone, may well be taken as the basement bed of the 

 gault just as we may regard the Cambridge Greensand as the 

 basement bed of the chalk ; and such I consider is the true aspect 

 of the Downham Phosphate bed. 



But our Ironsand and Phosphatic series (of Upware, Farring- 

 don, &c.) I regard as truly belonging to the lower Group (Upper 

 Neocomian or Aptien) which is very generally separated by a 

 distinct break from the overlying Gault series namely by the 

 ' Great Unconformity ' of Mr Judd as seen in Yorkshire, Lincoln- 

 shire, Hunstanton, Upware and Farringdon. 



1 Professor H. G. Seeley regards them as much older. 



