TABLE OF GEOLOGICAL PERIODS AND FORMATIONS 



XV 



Cretaceous 



Jurassic . 



Triassic 



SECONDARY OR MESOZOIC PERIOD. 



Upper Chalk (with flints). 



:Middle Chalk (with few flints). 

 -, Lower Chalk. 



Upper Greensand. 

 l^Gault. 



f Lower Greensand. 

 I Wealden. 



Upper 



i Lower 



( /Purbeck and Portland Beds. 



Upper \ Kimmeridge Clay (Solenhofen Slates in Bavaria.) 

 iCorallian and Oxford Clay. 



J Tif. J 11 ( Great Oolite. 



•< Middle I Inferior OoUte (Stonesfield Slate belongs here}. 



Upper Lias. 



Lower Middle Lias. 



Lower Lias. 



/' Yj (■ RhaeticBeds. 



P" \ Keuper Marls and Sandstone. 

 Middle : Muschelkalk, absent in Britain. 

 Lower : Buuter Sandstone, Pebble Beds, Karoo of S 

 Africa. 



Permian . 



Carboniferous . 



Devonian 



Silurian 



Upper Cambrian" 



Lower Cambrian 



Precambrian 



PRIMARY OR PALAEOZOIC PERIOD. 



/ Upper : Magnesian Limestone, 

 l Lower : Red Sandstones. 



TT ( Coal Measures. 



Upper I Millstone Grit. 

 Lower : Carboniferous Limestone and Shales. 



Upper Old Red Sandstone. 

 Limestones (marine). 

 I Lower Old Red Sandstone. 



(Ludlow. 

 Wenlock, 

 May Hill Sandstone (Llandovery). 



Bala. 

 Llandilo, 



Arenig. 



/•Tremadoc Series. 

 I Lingula Flags. 

 ' Menevian Series. 



Harlech Series. 

 I Olenellus Beds. 



L. Silurian of Murohison, Ordovician of Lapworth- 



