2 PROF. E. J. GARWOOD AKD MISS E. GOODYEAR [vol. lxxiv, 



map has been issued, namely, that published in 18-10, and no 

 explanatory memoir has yet appeared. 1 Two of the horizontal 

 sections published 3 by the Geological Survey, however, pass through 

 the district, and these throw some light on the views adopted by the 

 officers o£ the Survey regarding its general structure at the time 

 Avhen the district was mapped. 3 They regarded the rocks of Old 

 Radnor Hill as altered May Hill Sandstone, and the surrounding 

 limestone, together with that which occurs at Nash Scar 3 miles 

 away to the north-east, as altered Woolhope Limestone. 



Murchison, as shown by his description in ' Siluria,' considered 

 the district to be one of especial interest. 4 He draws attention to 

 the differences exhibited by the limestone at Nash Scar and Old 

 Radnor, when compared with the normal Woolhope Limestone and 

 Shale at Corton and Haxwell, and remarks, 



' between these two .... lies the large and loftier rock of Nash Scar, in 

 which the same limestones, whether thick -bedded or nodular, have been run 

 together into one amorphous mass, in which the stratified character has been 



destroyed, and the shale driven off In tracing- the strata southwards 



along this axis, other masses of limestone, more or less amorphous, are seen 

 near Old Radnor, which, in proportion as they approach the eruptive masses 

 of Stanner and Hanter rocks, and Ousel Hill, or the highly metamorphosed 

 rock of Old Radnor and Yat Hill, are themselves sub crystalline, and imbedded, 

 with coatings of serpentine upon the siu*faces of the joints. On the other 

 hand, on receding westwards from that line of eruption and metamorphism, 

 into the Vale of Radnor, to the south-east of Harpton Court, the limestone 

 begins to resume its bedded character, resting on the pebbly Caradoc conglo- 

 merates which range by Old Radnor Church and Yat Hill.' 



After referring to the geological section of the Government 

 Survey exhibiting the igneous rocks of Hanter Hill, he continues : 



' It is also suggestive of the fact, that another body of igneous rocks lies sub- 

 jacent to the Caradoc conglomerate and crystalline limestone of Old Radnor 

 and Yat Hill, where the coatings of serpentine and brecciated and altered 

 features of the stratified rocks are, in the eye of the geologist, conclusive 

 evidences in favour of such relations.' (Op. cit. p. 104.) 



Although Murchison admitted that the change in the character 

 of the limestone at Old Radnor must have been in a great measure 

 due to original deposition, he still considers that 



' its amorphous and massive condition at Nash Scar and Old Radnor was 

 doubtless caused by the action of heat issuing along a line of former linear 

 fissure, which, in some places, evolved the hypersthenic rocks and greenstones 

 of Stanner, Ousel, and Hanter upon the line in question, fused the stratified 

 limestone and the calcareous nodules of the shale into amorphous and hetero- 

 geneous masses, more or less crystalline, leaving coatings and films of serpen- 

 tine on their faces and joints.' (Op. cit. p. 105.) 



1 The only published references appear to be a note, in the abstract of a 

 paper by A. Ramsay & W. T. Aveline, entitled ' Sketch of the Structure of 

 Parts of North & South Wales ' Q. J. G. S. vol. iv (1848) p. 296 ; and in a paper 

 by Ramsay, entitled ' On the Physical Structure & Succession of some of th » 

 Lower Palaeozoic Rocks of North Wales & Part of Shropshire ' Q. J. G. S. 

 vol. ix (1853) p. 174. 



2 Sheet 56, S.E. New Radnor, Kington, etc. 



3 Sheet No. 27, 1852. <fc Sheet 58, 1860. 



4 ' Siluria ' 1st ed. (1854) pp. 103 et seqq. 



