TABLE OF GEOLOGICAL PERIODS AND FORMATIONS 



XV 



Cretaceous 



Jurassic 



Triassic 



SECONDARY OR MESOZOIC PERIOD. 



("Upper Chalk (with flints). 

 Middle Chalk (with few flmts). 

 ' Lower Chalk. 



Upper 



Lower 



Upper Greensand. 

 VGault. 



( Lower Greensand. 

 I Wealden. 



1 



/Purbeck and Portland Beds. 

 Upper ] Kimmeridge Clay (Solenhofen Slates in Bavaria. ) 



vCorallian and Oxford Clay. 

 TT- 11 (Great Oolite. 

 Middle I Inferior Oolite (Stonesfield Slate belongs here). 



( Upper Lias. 



Lower \ Middle Lias. 



''Lower Lias. 



y-r f RhaeticBeds. 



P^ I Keuper Marls and Sandstone. 

 Middle: Muschelkalk, absent in Britain. 

 Lower : Bunter Sandstone, Pebble Beds, Karoo of S 

 Africa. 



Permian . 



Carboniferous . 



Devonian 



Silurian 



PRIMARY OR PALAEOZOIC PERIOD. 



f Upper : Magnesian Limestone. 

 ' Lower : Red Sandstones. 



f Coal Measures, 

 "i Millstone ^ Grit. 

 Lower : Carb oniferoiis Limestone and Shales. 



Upper 



Upper Cambrian* 



Lower Cambrian 



Precambrian 



( Upper Old Red Sandstone. 

 J Limestones (marine). 

 I Lower Old Red Sandstone. 



f Ludlow. 

 J Wenlock. 

 May Hill Sandstone (Llandovery). 



f Bala. 

 I Llandilo, 

 I Arenig. 



Tremadoc Series. 

 Lingula Flags. 

 Menevian Scries, 

 Harlech Series. 

 Olenellus Beds. 



* L. Silurian of Murchison, Ordovician of Lapworth. 



