of the Vale of Wardour. 253 



the several beds at and near the junction of the two formations. 

 That this is so will be apparent when the two descriptions are 

 placed side by side (as below), but in order to indicate the correlative 

 beds more clearly I have taken the details of the Portlandian part 

 of the section from my notebook, in which the separation of the 

 beds composing this series was fully noted. 



Mr. Woodivard's account. 



Dark shaly clay, much squeezed 

 up in places. 



Our account. 



ft. in. 



6. Laminated brown and grey clay, with 



patches of black clay 4 



5. Hard whitish chalky limestone with 

 Cyprids, and a layer of cherty stone 

 with small lenticles of flint at the top 1 3 



4. Soft grey and white laminated marl ... 6 



3. Hard flaggy limestone with black flints 

 at the top, passing down into chalky 

 and shelly limestone ... ... ... 23 



2. Rubbly chalky limestone full of large 

 Pectens, with marked planes at top 

 and at base ... 1 



1. Chalky limestone with Portland fossils 13 



I Compact limestones, 2 feet. 



Bed of Roach, with lenti- 

 cular mass of chert at 

 top. 



Chalky limestones,obliquely 

 bedded, with Portland 

 fossils. 



10 to 

 15 



feet. 



Bed No. 3 of the above succession is made up of two parts : the 

 lower foot is a fairly compact, white chalky limestone, crowded with 

 the shells of Pecten lamellosiis ; the upper part is a flaggy limestone 

 without marine shells, but containing the Cyprides Gandona ansata 

 and C. bononiensis, which are marine and estuarine species : these two 

 beds are closely welded together, they project beyond the others 

 and usually break away in one block. Mr. Woodward follows 

 Fitton and others (who considered the flaggy stone to be a fresh- water 

 bed), and takes the plane along which they can be separated as the 

 line of division between the Portland and Purbeck Series. We, 

 having Professor Eupert Jones' assistance in determining the 

 Cyprides, recognized the flaggy bed as of estuarine origin, and 

 finding a marked plane at its summit, preferred to regard it as the 

 topmost bed of the Portland Series. 



I am quite prepared to admit that the beds which are welded 

 together do contrast strongly in lithological character, and if this 

 same kind of junction prevailed throughout the district, it would be 

 a matter of small importance whether the one plane or the other 

 were taken as the division between the two formations. It is 

 well known, however, that in the Chilmark quarries (only two 

 miles distant) there is a completely different development of beds 

 at this horizon; at that place there are 16 feet of oolitic limestones 

 between the top of the chalky limestone and the bed which is taken 

 as the base of the Purbeck Series. I have suggested that the flaggy 

 part of the 'junction bed' at Wockley is a reduced representative 

 of these oolitic limestones, for if it is not so, then it is certain that 

 these limestones can have nothing to represent them at Wockley,^ 

 and in that case one would have expected to find a very well-marked 

 plane of division between the Portland ' chalk ' and the base of th& 

 Purbeck Beds. 



