part 1] OX THE GEOLOGY OF THE OLD RADNOR DISTRICT. 21 



their nearest point of outcrop to the limestone, in Caen Wood, arc 

 unfossiliferous. There is, however, one small exposure in the 

 gully immediately north of Haxwell at the southern end of the 

 Scar, where a small anticline of limestone is seen overlying grit. 

 This grit is quite devoid of fossils, but does not differ essentially 

 from the unfossiliferous portion of the Pentamerus Grits occurring 

 farther north. According to Murchison, this section was formerly 

 much better exposed, and included a layer of normal Woolhope 

 Limestone and Shale between the grit and the Nash-Scar Lime- 

 stone. 1 At the present day, the section is much overgrown, and no 

 trace of these beds can be seen. Davis, on the other hand, remarks : 



' It [the Nash-Scar Limestone] undoubtedly, however, rests immediately on 

 the sand and grit beds. The connexion may be traced to within a few feet, 

 leaving at the utmost merely room for the intervention of a thin bed of 

 shale.' (Q. J. G. S. vol. vi, 1850, p. 434.) 



The Wenlock Shale is only seen in contact with the limestone at 

 the northern end of the Scar, close to the farm, and their junction 

 here, as alread} r mentioned, is a faulted one. The eastern boundary 

 of the .limestone appears also to mark a line of dislocation, which 

 forms a conspicuous feature along the east side of the road, between 

 Haxwell and Corton. It is evidently a continuation of the 

 Stretton line of disturbance, and links this with the faults bounding 

 the eastern margin of the Old Radnor Inlier. 



One important point in connexion with the Nash- Scar district 

 remains to be considered : namely, the fact that an outcrop of the 

 normal type of Woolhope Limestone and Shale occurs at the 

 * Sandbanks ' near Corton, a mile south of- Presteign, and about 

 the same distance from the typical reef -development at Nash Scar. 

 The old workings here are almost entirely overgrown ; but, accord- 

 ing to J. E. Davis {loc.jam cit.), the section in 18o0 showed a thin 

 band of highly-crystalline limestone about 8 feet thick dipping 50° 

 north-north-eastwards, and separated from the sand- or grit-beds 

 by a few feet of shale which also overlay it to a greater depth. 

 At the present day the overlying nodular shale can still be seen, 

 and the narrow trench from which the limestone has been extracted, 

 and in one place a small outcrop of dark bituminous limestone, can 

 yet be traced. A few years ago a boring for coal was put down in 

 the Wenlock Shale at this spot. We have not had the opportunity 

 of examining the complete core ; but, if we may judge from frag- 

 ments of the core found on the spot, the boring penetrated a 

 coarse conglomerate which closely resembles the Longmyndian 

 conglomerates of the Bayston Group and the grey conglomerate 

 of Old Radnor : this suggests the presence here of Pre- Cambrian 

 rocks forming a southward continuation of the Longmyndian 

 ridge that underlies the Llandovery grits of Caen Wood. This 

 sudden and remarkable change from the thick reef-facies of the 

 limestone at Nash Scar to the thin band of normal Woolhope 

 Limestone and Shale at the ' Sandbanks ' in a distance (at the 



1 ■ Sihiria' 1st ed. (1854) p. 103. 



