Quart, Journ. Geol. Soc. Vol. LXYIJ, PI. XXXIII. 



EXPLANATION: 



\Powis Castle Beds, etc. 

 (Llandovery) 



r Salopian 



Valentian 

 Ashgillian 

 Caradocian 



i PrvILy^glo Group 



^^Trilobite Dingle Shales \ n , ... „_.-,, 

 l=^d f^Dicranograptus Shalesji Olenklln-Hartfett 



