THE TECHNOLOGIST. [Oct. 1, 1864. 



136 ON THE POSITION AND MODE OP 



series, or middle beds, which occur between the " upper and lower rag- 

 stones." At Bradford, Westwood, and Murhill this bed is a coarse, shelly, 

 hard limestone ; at Corsham and Box, a closer-grained and tough rock. 

 I associate it with the building freestone, or fine beds below it, rather 

 than with the ragstone above, from its persistency and the constancy of 

 its conditions. Succeeding this is the true Bath stone, or fine freestone, 

 and which I believe occupy, with minor differences, the same position 

 or horizon over the whole of the Bath district. This second, middle, or 

 freestone series are as a group from twenty to thirty feet in thickness, 

 and are coloured chrome-yellow in all sections, and those beds worked 

 for transit are usually evenly grained in texture, regularly bedded, yield 

 well to the saw, are non-fossiliferous, and give evident proof of having 

 been accumulated or deposited in a somewhat deep and tranquil sea, or 

 away from any littoral or wave disturbance, and which the almost total 

 absence of organic remains still further tends to confirm or demonstrate. 

 It appears from observation, and the correlation of measured sections, 

 and conditions observable underground, that the fine-grained regular 

 beds thin away in a south-eastern direction, or upon the line of their 

 general dip, a fact clearly determinable on examining the sections ex- 

 posed in the valleys. Indeed, it cannot be doubted but that the great 

 or Bath oolite as a group, in this neighbourhood, exists under extremely 

 irregular conditions, and dies out and disappears in the form of a lenti- 

 cular or wedge-shaped mass, to the east and south-east. This circum- 

 stance, causing the building freestones to thus vary in their relative 

 thickness as we proceed from the western part of the area to the east and 

 south-east, and the removing of much of the exposed belt comprising 

 the oolitic series between Bath and Bradford, on the line of their strike, 

 north-east and south-west, caused, it would appear, by the extreme 

 denudation of the Bath and Bradford valleys, and the westerly exten- 

 sion of the cretaceous series from Melksham to "Westbury, Frome, and 

 Warminster, are due, perhaps, to physical conditions connected with 

 the eastern extension of the Mendip axis, and the little understood, 

 deeply-seated, but undoubted position of the Palaeozoic series, between 

 Frome on the south, and Bath and Wick war on the north, or along the 

 eastern edge of the Bristol coal-field ; but under any circumstances the 

 extension or invasion of the cretaceous series in the east, the narrowing 

 of the exposed oolitic series above-mentioned, and the mechanical ar- 

 rangement of the rock structures themselves, evince and determine local 

 deposition to have gone on under continued oscillation of the land at the 

 time of the deposition of the great oolite series. It is to fc this second 

 grouping, therefore, or the middle series, which exist between the upper 

 end lower ragstones, that we must assign the workable beds of freestone 

 now extensively quarried in the Bath district. 



The Lower Ragstones. — These are an extensive series of rather fine 

 and hard, as well as coarse and shelly, limestones. The lowest beds of 

 this series being usually finer in texture than the upper, and when 



