1 12 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [JlUie 1 7, 



different members or stages, which, though tolerably persistent, are 

 still liable to many variations ; these, however, are much more appa- 

 rent than real, as, though the beds vary much in colour and thick- 

 ness at different places, yet it is astonishing how clearly representative 

 rocks may be made out at distinct points.* Hence at Box we have 

 an example of an excellent building-stone, which, from its fineness 

 of grain, the freedom with which it can be worked, and the stability 

 of its form under atmospheric changes, is rendered one of our best 

 rocks for all fine architectural uses, and hence it is sent immense di- 

 stances for quoinings of buildings, stone-carvings, and the like. The 

 same stage, however, further north is very rough in texture, and by 

 no means a weather-stone ; besides, it can only be used in small pieces, 

 on account of its decidedly oblique lamination, the lines of which are 

 equally apparent in the Bath stone, though the latter holds firmly 

 together in these planes. 



The following is the best general analysis of this rock, in descending 

 order, 1 have been enabled to make by comparing sections in the 

 Minchinhampton, Cirencester, and Bath districts : — 



Subdivisions of the Great Oolite. 



ft. in. 



C. 6. Yellowish oolite, with more or less of oblique la- 

 mination, sometimes separated into two or more 

 stages with thin partings of sand or marl ; oc- 

 casionally a hard compact freestone throughout ; 

 about 45 



5. Bed of marl, mostly yellow, occasionally dark 

 blue, sometimes in clunchy lumps, containing 

 Lima cardiiformis and Ter. maxillata in quan- 

 tity, — in many places a hard white stone .... 4 



4. Hard limestone in blocks, with Purpuroidea, 



Pachyrisma, &c 6 



3. White limestone, breaking up into square blocks, 



occasionally with oblique laminae = Bath Oolite 30 



2. A rougher freestone (frequently blue-centred 

 =the " black rock" of the quarrymen). Rag- 

 stone 25 



1. Flat slabs of siliceous limestone, with square 

 sharp edges, fissile on exposure, frequently 

 highly charged with vegetable remains = Stones- 

 field Slate. This becomes sandy and incoherent 



towards the bottom 15 



Fuller's Earth 



Total 125 



As regards the upper bed (6) of this section, it may not be out of 

 place to state, that, while enjoying the pleasure of two or three field- 



* 'I hese, however, are only to be known by constant work and comparison 

 both of section and fossils. 



