192 



OUTLIERS OF OLD RED SANDSTONE IN RADNORSHIRE. 



mass is of an irregular oblong shape, being about four miles in length, from Oak Hill 

 on the north-east, to Norton Ruralt on the south-west, and has an average width of 

 about one mile and a quarter. On the north it is separated from the Old Red of Clun 

 by the valley of the Teme and the bold ridges of Ludlow rocks forming Stow Hill, and 

 on the east and south, it is completely cut off from the great area of Old Red Sand- 

 stone in Herefordshire, and from smaller outliers south of Presteign by other zones of Si- 

 lurian rocks. The hills of this outlier vary from 800 to 1350 feet in height, and 

 the surrounding elevations of Silurian rocks are pretty nearly of the same altitudes, Stow 

 Hill alone attaining a height of 1417 feet (Trigonometrical station, Holloway rocks) . 

 At Reeves Hill, near the northern and north-eastern boundary, the strata occupying 

 ground 1200 to 1300 feet high, dip south-east twenty degrees ; at Norton in lower 

 situations, north-east, and at Witley, north-west ; so that the outlier occupies a basin 

 which is of very irregular shape, owing to the dislocations and varied directions 

 of the older rocks which surround it 1 . Flaglike firestones, similar to those of Clun 

 Forest, are largely excavated at Reeves Hill, and thick-bedded red sandstones, of tole- 

 rably good building quality, at the quarries above Witley. The junctions of the Old 

 Red with the Ludlow rocks are not often well displayed, but the latter are visible in 

 many places near the former, dipping inwards, and therefore supporting this insulated 

 mass. On the other hand there are apparent unconformable junctions, particularly 

 to the west of Norton, doubtless produced by the dislocations which severed this 

 outlier from the main tract of Old Red Sandstone, with which it must once have been 

 continuous. Other separate but contiguous patches of Old Red Sandstone, cover the 

 grey surface of the upper Silurian rocks, on the sides of the hills south of Knighton, 

 but they are too thin and insignificant to be noticed. 



There is a third outlier of Old Red Sandstone, about half a mile south-west of Pres- 

 teign. This mass is of small size, merely occupying the western side of the Nash Scar 

 ridge called ' Lower Radnor's Wood,' and extending into the lower grounds between 

 that hill and Harley's Wood. The strata are there thrown up in vertical or highly in- 

 clined positions, with a strike from north-north-east to south-south-west, and consist of 

 thin-bedded, micaceous sandstone, with deep red argillaceous marl. The relations of 

 this dislocated mass of red sandstone to the contiguous Silurian rocks is explained in 

 PI. 33. fig. 2. 



A fourth, and the last outlier I have occasion to notice, is also in Radnorshire, and 

 lies to the south-east of the last-mentioned. It is likewise a narrow stripe, but is of 

 much greater length than that of Lower Radnor's Wood, being continuous for about 

 three miles from Weythell, south of Old Radnor, to Wernilla on the eastern flank of 



1 The position of the romantic cottage of Mr. R. Price, M.P., near Norton Ruralt, marks the extremity of 

 one of the tongues of Old Red Sandstone which, peninsulated amid the Silurian rocks, indicate the irregular 

 form of this outlier. 



