OOLIIE OF TUK COTTESWOLD HILLS. ^ISl 



this horizon and arc associates of //. opaliuum^ it is best to treat it 

 as the highest zone of the Lias." Mr. Hudleston, F.ll.H., takes a 

 different view, and says * : " Turning now to the lower boundary, 

 there seems to be a general opinion that the Sands of the Inferior 

 Oolite should be restored to their old position as part of that series, 

 which A\ ill, therefore, include the Cephalopoda-bed of the Cotteswolds 

 and its Dorsetshire equivalents. As a matter of fact there are but 

 few Gasteropoda in sufficiently good condition in these essentially 

 tninsit'ion beds between the Lias and tlie Oolites to make their 

 acquisition of much value, and consequently but few specimens arc 

 likely to be selected for description from them." The italics are 

 mine, and I have given the quotation because of the words " essen- 

 tially transition heels" for I regard the beds commencing with the 

 '' Sands " and ranging up to what I shall call the " Pea-Grit Series " 

 as transitional between the Inferior Oolite and Upper Lias. By the 

 name of Transition Beds I shall refer to them in this paper. 



For the most part the lowest beds of the Inferior Oolite and 

 uppermost beds of the Lias are covered by talus. It is therefore 

 not often that we have the advantage of seeing them ; but, during 

 the making of the Midland and South- Western Junction Kailway 

 between Andoversford (near Cheltenham) and Cirencester, a complete 

 succession of the strata betwixt the Upper Lias and the Pea-Grit 

 Series of the Inferior Oolite has been exposed. This section has 

 been briefly described by Mr. S. S. Buckman in the Proceedings of 

 the Cotteswold Naturalists' Field Club for 1889-90. It occurs in 

 the third cutting east of Andoversford, and the following is a vertical 

 section of the beds in ascending order : — 



Section of the Transition Beds E, of Andoversford., 

 near Cheltenham. 



ft. in. 



6. Argillaceous beds with Calcareous Nodules 10 



5. Irregular bedded material, mostly argillaceous, with 



Rhynchonella cynocejjhala at the base 12 



4. Calcareous Bed 10 



3. Cephalopoda-bed 1 2 



2. Crystalhne Limestone 6 



1. Representative of the Midford Sands 3 6 



The L'pper Lias. 



28 



The Midford Sands are represented by an arenaceous stratum, 

 samples from which give no reaction with hydrochloric acid. Then 

 follows a light-coloured limestone, 6 inches thick, which appears to 

 have escaped the notice of previous observers. Thin sections of it 

 prove that the limestone is crystalline, and for this reason some of 

 the organic remains are not determinable. Among those which could 

 be made out are the ossicles of crinoids, spines, shell-fragments, and 



* ' Monograph of the British Jurassic Gasteropoda,' Pal. Soc. vol. si. (1880) 

 p. 19. 



