484 T. C. Cantrill — Coal-boring at Presteign, RadnorsJiire. 



Pentanierus Beds from the Caradoc Sandstone, and adopted the term 

 " Upper Llandovery Rock" for the Corton Grit, in which he noted 

 the occurrence of Pentamerus oblongus, Atrypa hemispherica, Petraia 

 elongata, and P. bina. 



The Rev. W. S. Symonds ' appears to have been one of the first 

 observers to perceive that the Presteign Limestone is of Woolhope 

 and not Wenlock age. He based this conclusion on the facts that 

 here, as elsewhere^ the limestone in question follows immediately 

 upon the "Caradoc" [i.e. the Upper Llandovery], and contains 

 Illcenus barriensis and Homalonotus hiighti in far greater abundance 

 than does the Wenlock formation. The same author, in a later and 

 better-known work, 2 remarked that as early as 1850 he had 

 correlated the Presteign Limestone with that of Woolhope by its 

 position with respect to the Upper Llandovery beds and from its 

 containing Illeenus barriensis in abundance. 



Turning now to the current edition of the Geological Survey maps 

 (Sheets 56 N.E. and S.E.), we see that Presteign stands on a great 

 line of faulting, which, ranging in a south-south-westward direction 

 from beyond Church Stretton, runs through Bucknell in the Teme 

 Valley, passes Presteign, and, five miles farther to the south-west, 

 near Old Radnor, brings to the surface the ancient igneous rocks of 

 Stanner, Worsell, and Hanter. 



On the western or downthrow side of this fault a broad strip of 

 Old Red Sandstone extends from Bucknell to within a mile of 

 Presteign. Though now cut through by the valley of the Lugg, 

 this strip was once continuous with a second tract of the same 

 formation, which underlies Upper Radnor Wood and Knill Wood, 

 south-west of the town. 



On the eastern or upthrow side of the fault, grey calcareous sandy 

 nmdstones of the Ludlow formation extend from Brampton Bryan 

 Park to within a mile of Presteign, where they give place to the 

 Wenlock Shales, though these are concealed for a space by the 

 superficial gravels and alluvia of the Lugg. Southward, beyond 

 these valley deposits, the lowest beds of the Wenlock Shales soon 

 emerge along the northern slopes of the anticlinal ridge of Nash 

 Wood and Corton. For a distance of half a mile along the northern 

 foot of this ridge, and dipping northward from it at an angle of 41°, 

 a lenticular outcrop of the Woolhope Limestone comes to the surface 

 at the spot named Folly 3 on the Map (56 N.E.), thinning out to 

 a point, both eastward and westward, between the Wenlock Shales 

 above and the Upper Llandovery Rock below. Immediately south 

 of the limestone outcrop rises the Corton ridge itself, which consists 

 of Upper Llandovery Rock, locally known as the Corton Grit. Several 

 dip-arrows on the map show that the ridge is an anticline. It 



1 Old Stones, 8vo, 1855, pp. 59, 60. 



2 Becords of the Rocks, 8vo, 1872, pp. 139, 140, 160. 



3 On the Ordnance Map, which was published October 1, 1833, this name is 

 placed at the northern foot of the ridge, where the lane from the town begins 

 its diagonal ascent. It may have referred to a cottage shown above the old 

 limestone quarries. The cottage is still remembered by old inhabitants, 

 but the name now applies to the farm on the crest of the ridge. 



