300 JURASSIC. 



Great Oolite, and the following general section was noted by Dr. 

 J. Lycett :' — 



feet in. 

 "Planking." Coarse shelly oolitic limestone, false-bedded. 

 Purpiiroidea, Plcroperna, Macrodon and other large 



shells lo o 



Thin-bedded pale oolite, with sandy partings : more compact 



at base. Ostrea, Tancredia, etc 12 o 



False-bedded yellowish oolite. LitJiodonnts incliisjts 6 o 



" Weatherstone." Greyish-brown oolite full of shells 6 o 



Hard argillaceous limestone, and flaggy oolite. Ostrea. 9 



Fuller's Earth. 



From the quarries in the neighbourhood Dr. Lycett obtained 

 up^vards of 300 species of Mollusca. The beds of Oolite here are 

 grouped with the Lower Zone, the Upper Zone being scarcely 

 represented at this locality : at the same time it is worthy of 

 remark that in this district there often appears to be no positive 

 line of separation between the Great Oolite and the Forest Marble.^ 

 Sections showing the two zones of Great Oolite have been exposed 

 at Yatton Keynell, near Corsham, and east of Castle Combe. ^ 



Other fossiliferous localities are Bussage, west of Chalford ; near 

 the Seven Springs, to the west, and Windrush and Sherborne Park 

 to the east of Northleach ; Cirencester ; Burford ; and Andoversford. 



At Sapperton Tunnel the thickness of the Upper Zone of white 

 limestones is about 30 feet ; but the total thickness of the Upper 

 Zone of Great Oolite is from 60 to 80 feet. The beds are blue 

 when reached at some depth, but they weather white, and hence 

 are locally known as the white limestones. They contain plant- 

 remains and jet, in some localities. In a quarry by the railway 

 south of Cirencester station, beneath the Bradford Clay, there is 

 a marly bed of Great Oolite crowded with specimens of Acrosalenia 

 piistidafa, to which attention was drawn by Mr. F. Bravender. The 

 total thickness of the Great Oolite at Cirencester has been proved 

 to be 120 feet; at Coin St. Dennis, the beds have a thickness 

 of 145 feet. The beds may be seen also at Brackley, and Whittle- 

 wood Forest, north of Buckingham, and around Towcester. 

 (See sequel.) 



Economic products, etc. 



At Tainton, near Burford, the Great Oolite yields excellent building-stone, 

 Icnown as the Tainton stone, which was much used in Oxford, and in the con- 

 struction of Blenheim Palace.* The beds are also quarried near Cirencester, 

 Kemble, Tetbury, etc. At Minchinhampton there are extensive quarries 

 (Hampton stone), showing thirty to forty feet of rock. The beds are also worked 



^ The Cotteswold Hills, p. 93 ; see also E. Witchell, Geol. Stroud, p. 73. 



- Hull, Geol. Cheltenham, p. 65 ; see also A. H. Green, Geol. Banbury, p. 17. 



•^ Hull, Geol. parts of Wilts, etc., p. 14. 



•* Hull, Explan. Sheet 45 S.W. (Geol. Survey), p. 16. 



