12 



Systems. 



NEOGENE . 



PALAEOGENE 

 CRETACEOUS 



STRATIGKAPHICAL GEOLOGY 



Primary Divisions. 



Relative Thickness. 



( Pleistocene. 



Pliocene. 

 I Miocene. 



(Oligocene. 

 I Eocene. 



/ Upper. 

 I Lower. 



I" Upper (White Jura). 

 JURASSIC . . - Middle (Brown Jura). 



TRIASSIC . 

 PERMIAN . 

 CARBONIFEROUS 



DEVONIAN. 

 SILURIAN . 

 ORDOVICIAN 

 CAMBRIAN 



I Lower (Lias). 



f Keuper. 



- Muschelkalk. 

 I Bunter. 



/"Magnesian Limestone (Zechstein). 

 I Red Sandstone (Rothliegende). 



l Stephanian. 



-| Westphalian (Coal-Measures). 

 lAvonian (Carboniferous Limestone). 



l Upper. 

 \ Middle. 

 I Lower. 



fDowntonian or Ludlow Beds. 

 *. Salopian or Wenlock Beds. 

 I Valentian Llaudovery Beds. 



l Bala Series. 



- Llandilo Series. 

 I Arenig Series. 



( Upper (Olenian). 



\ Middle (Paradoxidian). 



I Lower (Olenellian). 



NEOOENE 



CRETACEOUS 



CARBO- 

 NIFEROOS 



DEVONIAN 



ORDOVICIAN 



The actual thickness of any system of strata varies of course in 

 different parts of the same country, and for the construction of 

 the diagram the full average thickness of each stage has been taken 

 from English districts where the whole system is well developed. 

 The diagram does not, therefore, show the maximum thickness of 

 any system. Moreover, in other parts of the world the Permian 

 and Triassic Systems are represented by marine deposits which 

 reach a thickness of 9000 to 10,000 feet. 



