TABLE OF GEOLOGICAL PERIODS AND FORMATIONS 



XV 



Cretaceous 



Jurassic 



Triassic 



MMdle 



SECONDARY OR MESOZOIC PERIOD. 



Chalk (with flints), 

 le Chalk (with few flints), 

 j Lower Chalk. 



Upper Greensand. 

 VGault. 

 ( Lower Greensand. 



Upper 



Lower 



\Wealden. 



( /Purbeck and Portland Beds. 



Upper -I Kimmeridge Clay (Solenhofen Slates in Bavaria. ) 



vCorallian and Oxford Clay. 

 ,,.-,, (Great Oolite. 



le (Inferior OoliteJ(Stonesfield Slate belongs here). 



( Upper Lias. 



Lower j Middle Lias. 



^ Lower Lias. 



I 



\Keuper Marls and Sandstone. 

 Middle: Muschelkalk, absent in Britain. 

 Lower : Bunter Sandstone, Pebble Beds, 

 Africa. 



Karoo of S 



Permian . 



Carboniferous . 



Devonian 



Silurian 



PRIMARY OR PALAEOZOIC PERIOD. 



/ Upper : Magnesian Limestone. 

 ^ Lower : Red Sandstones. 



( TT ( Coal Measures. 



Upper | M}llstone Grit> 



( Lower : Carboniferous Limestone and Shales. 

 ( Upper Old Red Sandstone. 

 ' -c Limestones (marine). 



Lower Old Red Sandstone. 



f Ludlow. 

 J Wenlock. 



I May Hill Sandstone (Llandovery). 



( Bala. 

 Upper Cambrian* J Llandilo, 



Lower Cambrian . 



Tremadoc Series. 

 Lingula Flags. 

 Menevian Series. 

 Harlech Series. 

 Olenellus Beds. 



Precambrian 



L. Silurian of Murchison, Ordovician of Lapworth. 



