ZONE OF AMMONITES BUCKLANDI. 6b 



Glamorganshire, Somerset, and Dorset. This zone of life is characterised throughout by 

 the ])revalonce of a number of large JmtiioiiUes belonging to the natural group Andes 

 (von Buch), and by many Conchifcrfi of the genera Lima and Gri/phccd. In I'^ngland it 

 everywhere consists of beds of bluish argillaceous limestone, interstratificd with beds of 

 marl, shale, and clay of a similar colour. In some parts of Warwick, Somerset, Dorset, 

 and Glamorgan, this series attains a thickness of 80 feet. , 



GloucesfersJiire and SomersetsJiire. — In Gloucestershire it was partly laid open by the 

 deep cutting of the Dean Forest Railway at Ilighnam, and it is seen in the Lias limestone- 

 quarries near Tewkesbury, and in the natural escarpments at Frethern and Purton-on-thc- 

 Severn. In Somersetshire it was fully exposed in making the Great AVestern Railway be- 

 tween Bristol and Bath, and probably at no point were the several beds of the Lima series 

 better shown than in the cutting at Saltford, seven miles from Bristol. My friend, Mr. William 

 Sanders, made the following section during the execution of the work which, together 

 with his notes on the fossils contained in the different strata, has been kindly communicated 

 by my friend, Mr. Etheridge. This section is of great value, inasmuch as the beds are now 

 partially concealed by debris and vegetation, and the characteristic fossils can no longer 

 be found in their respective beds. 



Section of the Lower Lias Beds at Saltford, seven miles from Bristol, on the Great 



Western Mailway} 



• LiTHOLOGY. Thickness. Organic Remains. 



No. feet. 



Brown gravelly marl 120 



Beds of laminated shale and clay 110 



Dark clay, with boulders, and layers Scales of Tetragonolepis and Belemnites acutus, 



of septaria at the top and bottom of Mill. 



the bed, and in the clay between 105 



59. Gray Lias limestone 100 Rlnjnctionella variabilis, ^chloih.. 



58. Dark shale Belemnites acutus, M.i\\. 



Gray Lias limestone. 



Dark shale Ostrea Iceviuscula, Sow., Avicula, and Pecten. 



57. Gray Lias limestone Am7nonifes Con7/ljeari,SQW., aiidBelemn.acutus,Mil\. 



Dark shale. 

 56. Thin limestone-band. 



Dark limestone Nautilus striatus, Sow., Am. Conybeari, Sow., and 



Belemnites acutus. Mill. 



1 This section shows the relative position of the zones of Atnmonites Bucldandi and Am. planorbis and 

 the Avicula contorta series in this part of the county, and affords a good type for comparing these zones 

 in Somersetshire with the same groups in other parts of the south of England. 



9 



