200 



J. F. BLA.KE AXD W. H. HUDLESTON OX 



The whole thickness thus described amounts to little more than 

 25 feet, which would not appear to be so much as it attains in the 

 direction of the outcrop, but is nearly the whole where seen, the 

 rubbly nature of the upper beds pointing to a change in character 

 coming on above. The form thus exposed is not unlike the general 

 development throughout this range. The fossils of these quarries 

 come chiefly from the upper beds, Nos. 2 and 4, GerviUia aviculoides 



They are : — 



being left almost alone in Xo. 7. 



Ammonites cordatus (Sow.). 

 ■ perarmatua {Sow.), var. 



Ceritkium muricatum (Sow.), var. 

 Gervillia aviculoides (Soiv.). 

 Pholadomya coneinna (Ag.). 

 Pecten fibrosus (Sow.). 



Pecten lens (Sow.). 

 Ostrea gregaria (Soto.). 



clilatata (Sow.). 



Exogyra nana (Ph.). 

 Serpula tricarinata (Sow.). 



which is very much what we might expect, though not a very rich 

 list. The nature of the Lower Calcareous Grit, as it runs on to the 

 north, will be seen in the sections we shall give subsequently with 

 reference to the higher beds. 



Overlying the sand and grit in the neighbourhood is an untested 

 thickness of marly clay, as stated by Lonsdale ; but very little can be 

 seen of it. In a well close by the great quarries, near the Union 

 "Workhouse, after passing through 20 feet of blue oolitic rock, 10 feet 

 of this was sunk into ; it consists of light hard marl with indurated 

 lumps surrounding ill-preserved shells such as Natica, Alaria, and 

 Lima. It may also be seen underlying Coral Rag, on the west of 

 Fisher's Brook, a stream running parallel to and west of the Wootton- 

 Bassett road. This marl alone represents the great intervening 

 deposits of other localities, and is quite an exceptional development 

 at that period, though not absolutely unique. It recalls the marls 

 and marly pisolites which constitute so much of the Corallian beds 

 of the Xorth-Dorset district. 



The most interesting portion of the Corallian beds, however, in 

 this neighbourhood is the uppermost. Proved by stratigraphy and 

 by fossil contents to be of the same age, there is a marvellous 

 variety of rocks whose lithological characters have scarcely any thing 

 in common. First there is the true Coral Rag, formed of great 

 masses of Thamnastrcm, with intervening brash ; this may be traced 

 up to the Kimmeridge Clay, all round the stream that runs down 

 from Quemerford, where it presents its usual well-known characters 

 and fossils, and of which we need say no more. Traced towards the 

 town we see beds of large-grained oolite becoming mixed with it, 

 sometimes above and sometimes below the Rag, but always, like it, 

 containing Cidaris floricjemma ; and thus we are led on to the 

 second form, which is seen in the great freestone quarries at the 

 Union. 



These exhibit a face of 25 feet, made up of beds about 1 foot 

 to 2 feet in thickness, of more or less perfectly false-bedded oolite, 

 the dip of the false-bedding being towards the X.E. In some parts 

 the oolitic structure is little marked, the layers are more consoli- 



