6 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



[Apr. 6, 



and beds of pisolite or pea-grit, strongly impregnated with the same 

 mineral. The freestones are in many places overlaid by a bed of 

 cream-coloured marl, containing a vast quantity of Terebratula fim- 

 bria, Sow. In the neighbourhood of Cheltenham this zone is well 

 exposed, and here appears to have attained its greatest development. 

 The aggregate thickness of the pea-grit, freestone, and marl is 

 about 190 feet. In the Southern Cotteswolds these beds become 

 gradually thinner the further they are traced southwards ; and at 

 Dundry they almost entirely disappear. In the eastern direction 

 the same result is found to exist : at Turkdean, near Northleach, the 

 zone is only about 50 feet in thickness, and at Sherborne about 

 5 feet ; near Burford it has entirely thinned out, and there the 

 Inferior Oolite is represented by the upper ragstones of the zone of 

 Ammonites ParMnsoni* . 



A. Sections of the Inferior Oolite in Gloucestershire. 



Leckhampton Hill, near Cheltenham, presents one of the most 

 typical sections, in Gloucestershire, of the three subdivisions of the 

 Inferior Oolite, where the following beds are admirably exposed. 

 Beds Nos. 1, 2, and 3 represent the zone of Ammonites Parlcinsoni ; 

 bed 4, the zone of Ammonites Humjohriesianus ; and beds 5, 6, and 

 A, B, C, the zone of Ammonites Murchisonce. 



Fig. 1. — Section of LecJchanvpton Hill. 



Leckhampton Hill. 



|-{! 



1. Trigonia-bed. 



2. Gryphsea-bed. 



3. Brown rubbly oolite. 



4. Flaggy freestone. 



5. Fimbria-bed or oolite-marl. 



6. Freestone. 



A, B, c. Pea-grit and ferruginous oolite. 



D. Cephalopoda-bed. 

 E, F, G. Upper Lias sand and Upper Lias clay. 



h. Marlstone. 



I. Lower Lias clay. 



* Much valuable information, and many accurate sections, are given in my 

 friend Mr. Edward Hull's excellent memoir on the country round Cheltenham. 

 See ' Memoirs of the Geological Survey,' together with sheet 44 of the Map of 

 the Geological Survey of Great Britain, surveyed by Mr. E. Hull. Considt also 

 M. Triger's memoir on the Inferior Oolite of England, Bulletin de la Societe 

 Geologique de France, 2 e serie, torn. xii. 1854-55, pp. 73-79. 



