Mr. Lonsdale on the Oolitic District of Bath. 259 



The western boundary of the forest marble^ as far as Norton St. Philip, has 

 been aheady described, in detaihng- the superior boundary of the great ooHte. 

 From Norton it winds around Baggeridge to Falkland Knowl, Falkland, and 

 the brow of the hill descending to Radstock : there it turns eastwards, and 

 keeps nearly parallel with the main road to Frome. The line which separates 

 the forest marble from the cornbrash being extremely irregular, it is purposed 

 to mention only the leading points through which it passes. From the neigh- 

 bourhood of Yatton Keynell, where the breadth of the formation is small, the 

 boundary pursues an undulating course by Biddestone to Lower Pickwick, 

 where it takes an eastern direction by Pound Pill, Linleys, Gastard, and Sand 

 Pitt to Potter's Mill ; then by Shut-in-Lane, Wick Farm, Chapel Knap, and 

 Whitley to Atford ; whence it passes by Cottle's Farm, Flinch Bottom, Upper 

 Wraxhall, New House Farm, Ford Farm, Bradford-Leigh, Wooley, the Folly 

 near Bradford, Westvvood, Telisford, Langham Mill, Roade and Shoalford, to 

 Beckington. At this village an elevated ridge of forest marble commences, 

 and extends to Cutteridge. Beyond Beckington the boundary may be traced 

 by St. George's Cross, Oldford Hill, Fromefield, and Stiles Hill to Keyford. 



The greatest breadth of the forest marble is from Pert (a small hamlet a 

 little to the south of Norton), to the brow of the hill descending towards 

 Radstock by Green Parlour. The horizontal distance between these points 

 is about four miles, and, but for the denudation around Hardington, would 

 there constitute a leading feature in the geological structure of the country. 



Coriibrash. 



This formation possesses but little interest. It appears generally as a thin 

 stratum of rubbly stone, having considerable uniformity of character. The 

 nodules or masses are seldom more than a foot in diameter, and are for the 

 greater part much less. In those localities where circumstances have preserved 

 the deposit from denudation, the bottom bed affords a tolerably compact rock, 

 fitted for the construction of rough walls. The stone is exceedingly tough, 

 and varies in colour from almost white to a dingy brown ; but the lower part 

 of the stratum at the junction of the subjacent clay is frequently blue. On 

 being broken, the substance of the nodules exhibits generally a close, pasty, or 

 earthy texture, sometimes of great evenness of composition, sometimes of a 

 variable degree of consistency, irregular layers of a soft nature traversing the 

 blocks, and apparently pointing out that their decomposition is the origin of 

 the rubbly form of the superficial or exposed parts of the deposit. The corn- 

 brash assumes occasionally a crystalline structure. 



The surface occupied by this formation is comparatively small, and ex- 



2l2 



