vi. SERIES OF ANCIENT STRATA. 73 



FORMATIONS OF THE LOWER PALEOZOIC PERIOD, WITH ESTI- 

 MATES OF THEIR AVERAGE THICKNESS. 



feet. 

 Ledbury . . . . . . 25O-< 



Upper 



SlLUEIAN 



1 



( Arenaceous. 

 Ludlow ....... 1000 < Calcareous. 



( Argillaceous. 

 Calcareous. 



_Mayhill (or Upper Llandovery) . . 500 Arenaceous. 



fLower Llandovery ..... 750 Arenaceous. 

 LLower Caradoc or Upper Ba!a " ' 'H 

 [jJandeao or Lower Bala . .. . '.*{ 



f'Tremadoc ....... 1500 Argillaceous. 



Ffestiniog ...... 2500 Argillaceous. 



Longmynd ...... 8000 Argillaceous. 



H.750 



From this it appears plainly how great a defect of sea-action 

 must be allowed for, in treating of the lower paleozoic strata of 

 Malvern, between the Cambrian and Upper Silurian rocks how 

 great a lacuna in the series of life. Again, the Cambrian strata 

 of Malvern do not occupy in thickness more than one-tenth of 

 that here assigned to the same groups in Wales, less than one-tenth 

 if we adopt the thickness ascribed to them by the National Survey. 

 It is not therefore surprising that the Cambrian fossils of Malvern 

 are few. More may we wonder that, while agreeing generally with 

 their contemporaries in Wales, they often differ specifically. Lastly, 

 the upper Silurian series of Malvern, which is very complete as 

 to the strata, is equally full in its groups of life, and those for 

 the most part agree with contemporary associations in other parts 

 of the old Silurian sea. Thus both differences and agreements 

 concur in support of the geological theory in regard to the vast- 

 ness of paleozoic periods, and the definite succession of life in 

 large tracts of the sea. 



In the following Tables the genera of the fossils found in the 

 lower palaeozoic strata of Malvern, including Mayhill and the 

 Abberley Hills, are placed under their several natural classes, and 



