THE TECHNOLOGIST. [Oct. 1, 1864. 



134 ON THE POSITION AND MODE OP 



member of the oolitic series concerns us only by position, and is in tliis 

 district west of Corsham and Bradford a most persistent and important 

 zone, between the inferior oolite beds below and the lower ragstones of 

 the great oolite above, and, in some places, very fossiliferous, and varies 

 in thickness from 150 feet to 200 feet. Taking, therefore, as our guide 

 in this district the above three divisions of the great oolite, we are 

 enabled to construct vertical sections to aid us in our determinations as 

 to the position and condition of the few feet of stone profitable to work 

 in the series, or the " freestone beds," at all times an anxious and im- 

 portant question when seeking for and developing new ground. In this 

 paper I deal chiefly with facts, and therefore give detailed and measured 

 sections of type localities, from which may be determined by compari- 

 son the probable conditions under which the beds may occur at in- 

 termediate and unexplored stations or localities on the table lands be- 

 hind such outstanding mural precipices as Farley, Murhill, Box, on the 

 eastern side of the Bradford and Slaughterford valleys, or on the elevated 

 downs at Claverton, Combe, Hampton, Freshford, &c, to the south of 

 Bath, and west of the Bradford Valley, and on the receding fiats to the 

 east of Monklow, Farleigh, and Bradford, &c, conspicuous for the nume- 

 rous quarries opened in the cornbrash and forest marble, the latter of 

 which occurs in detached patches or continuous lines, stretching from 

 Malmesbury on the north, to Chippenham, Bradford, and other locali- 

 ties to the east of Bath, and especially conspicuous near Corsham, Chapel 

 Korap, South Wraxall, and on to Melksham. The most complete sec- 

 tion, and which may be regarded as a typical one of the great oolite and 

 forest marble beds of the Bath district is that of the Box Hill and Cor- 

 sham Quarry workings. No. 1, showing those beds not usually seen or 

 exposed, but which were cut through by the construction of the Box 

 Tunnel, and which we are now extensively working in that neighbour- 

 hood. Another exposition of the series is shown at Murhill, on the 

 eastern side of the Bradford Valley, where the three divisions into which 

 the series group themselves may be studied in situ. Also at Upper 

 Westwood, on the opposite or west side of the valley, other sections 

 occur, tending to show the same facts ; and the variable condition and 

 thinning out of the same beds upon the line of Diss, even at this short 

 distance. 



The Sections. — The shafts which are constructed along the line of the 

 Box Tunnel, on the Great "Western Bailway, afford at the several points 

 where they are carried through the beds of the great oolite accurate data 

 for the construction of sections and clear evidence of the succession of 

 the strata comprising the three divisions. I have endeavoured to main- 

 tain, as occurring through this district, and being situated considerably 

 to the east of the Bath Valley escarpments, a large area, for the produc- 

 tiveness of that area is estimated by the lie, position, and condition of the 

 building freestones, supposed to occupy the summit of the table land, 

 stretching from the eastern escarpment of the Bradford, Box, and 



