Geology of Wiltshire. 



317 



The following subdivisions may be observed in this district, and 

 can be distinguished both by lithological and fossil characters : — 



Inferior Oolite. JRodborough Common. 



Upper ragstone. (Clypeus grit.) Coarse rubbly white oolite, with 



Terebrntula glohata, Clypeus, Serpula _ _ _ 



Lower ragstone. Shelly limestone, rather sandy, and irregularly 



bedded, with casts of Trigonia costata, Gryphaa Buckmani 

 Upper freestone. Compact oolitic freestone, quarried for building 



purposes _______ 



Oolite marl. Cream-coloured marl and chalky limestone, characterized 



by Terehratula fmhria ------ 



Lower freestone. Massive, fine grained oolite, false bedded ; becoming 



coarser and somewhat sandy towards the base; quarried for building 



No. 1. 

 Section at WalPs Quarry, North of Minchinhampton. 



a Upper Ragstone. Not shown in section, 



similar to that of Eodboroiigh Common 



a Lower Ragstone - - - - 



b Upper freestone _ _ - - 



c Oolite marl _ _ - _ 



d Lower freestone _ _ _ _ 

 Beds not seen at base of Inferior Oolite 



Feet. 



15 



25 



15 



30 



90 



12? 



9 

 10 



3 

 15 

 10 



59 



The Beds marked (c) in the woodcut are Upper Lias 

 Sand. 



From a comparison of these sections it will be observed that the 

 formation has lost some of its thickness in the distance from Rod- 

 borough Common to Wall's Quarry. This fact is in harmony with 

 the observed attenuation of the Inferior Oolite, both towards the 

 east and south from Leckhampton Hill, the typical section of this 

 formation.^ 



The fossils of this formation are so numerous that it is only 

 necessary to mention here a few of the more typical. 



' Compare the Maps of the Geological Siirvey 44 and 35. Also Memoir on 

 the Geology of Cheltenham, pp. 31 — 47. 



VOL. XI. — NO. XXXIII. 2 C 



