GREAT OOLITE. 299 



W. H. Wickes. The Corals in the opinion of IMr. Tomes are 

 drifted. 



The Great Oolite forms the summits of Lansdown and of the 

 principal hills south and east of Bath. It occurs at Bradford-on- 

 Avon ; but it thins away entirely in the district north of Frome, 

 between Wellow and Norton St. Philip,^ and is therefore not 

 present in Dorsetshire. 



In the northern part of the Cotteswold district Prof. Hull found 

 it convenient to divide the Great Oolite as follows :" — 



J J ["White limestone," compact white marly lime- 



yPP I stones, seldom oolitic, and marls or clays ; about 

 ( 100 feet at Burford. 



Lower ( White oolitic freestone, false-bedded. ) 1 2 to 

 Zone ( Stonesfield Slate j 80 feet 



The Upper Zone, as Prof. Judd states, possesses a distinctive 

 fauna, in which Myidce, Ostreidce, and Echinodermata are especially 

 noticeable ; it may be traced from the northern end of the Cottes- 

 wolds, through Oxfordshire and Northamptonshire to Lincolnshire. 

 In the neighbourhood of Bath it is represented by the Upper 

 Rags. (See p. 298.) 



The Lower Zone contains remains of terrestrial organisms and 

 indicates the littoral conditions under which it was deposited. 

 Traced towards the Midland counties, the Lower Zone is represented 

 by sandy beds (Northampton Sand, upper part), and still further 

 north by estuarine clays (Upper Estuarine Series). The Bath 

 freestone and beds beneath belong to the Lower Zone.^ 



The Lower Zone of the Great Oolite includes the Stonesfield 

 Slate, which was shown by Lonsdale to lie at the base of the Great 

 Oolite.^ It comprises not only flags and tilestones, but also white 

 shelly oolites, which in some places overlie the flags, and in others 

 replace them. These oolites or freestone beds, which attain a 

 thickness of from ten to nearly forty feet, are worked at Minchin- 

 hampton, Burford, Tainton, and Windrush. 



In the neighbourhood of Banbury the beds become sandy, and 

 there they have been included in the Northampton Sands, although 

 their true position as part of the base of the Great Oolite was 

 recognized by Mr. T. R. Polwhele.^ (See Diagram, p. 286.) 

 Terebrahila maxiUata, RhynchoncUa coiicinjia, Cypricardia Batho- 

 nica, and other fossils were obtained from these Sands near 

 Deddington. 



At Minchinhampton extensive sections have been opened in the 



^ The inlying mass at Wanstrow, Isetvveen Bruton and Frome, represented on 

 the Geological Survey Map as Great Oolite, is in reality Fuller's Earth. 



' Geology of Cheltenham, p. 53 ; Judd, Geology of Rutland, etc., p. 10. 



^ Hull, Explan. Sheet 34 (Geol. Surv.), p. 13. 



* Proc. G. S. i. 414; see also Dr. W. H. Fitton, Zool. Journ. 1828, iii. 412. 



^ A. H. Green, Geol. Banbury, etc. p. u ; see also Judd, Geol. Rutland, 

 etc. p. 25, 



