part 3] silurian rocks of the clun-fobest district. 223 



Previous Work. 



The country was mapped on the 1-inch scale by the Geological 

 Survey in 1819, l and a horizontal section 2 is taken almost along 

 the line of the liedlake Valley. No descriptions were published, 

 and Jukes-Browne, 3 writing in 1912, sums up the information 

 concerning the district in these words : 



' In the country round Kington, Clun, and Radnor Forest these graptolitic 

 shales [Lower Ludlow] are succeeded by a great thickness of brownish sandy 

 shale with beds of brown flagstone and sandstone, which are shown in the 

 sections of the Geological Survey to be from 1700 to 2000 feet thick.' 



Murchison 4 mentions the absence of the Ludlow Bone-Bed in the 

 Clun Forest, and gives reasons for including the ' Tilestones ' in 

 the Silurian rather than in the Old Red Sandstone sequence. He 

 also mentions the occurrence of carbonized plant-remains in the 

 Tilestones of Clun Forest, and emphasizes 5 the ' gradual mineral 

 transition ' from Upper Silurian to Old Bed Sandstone rocks. 

 He adds, however, that the area occupied by the latter formation is 

 well shown by the reddish colour of the soil, though in some places 

 soil of similar colour is also formed by the highest beds of the Upper 

 Ludlow Series. 



The Ludlow Bone-Bed certainly occurs in the extreme north of 

 the area near Bishop's Castle, 6 and also in a modified form in the 

 south-east near Kington 7 ; but all efforts to trace it over the greater 

 part of the Welsh Border district have failed, and the absence of 

 this important band has doubtless hindered the correlation of the 

 Transition Beds. 



II. Topography and Surface-Geology. 



The scenery, although presenting no remarkable features, affords 

 a good example of a landscape controlled b} r geological structure. 

 The district comprises a series of hills ranging in height from 1200 

 to 1500 feet, separated by valleys often nearly 1000 feet deep. 

 The hills have generally a steep, thickly -wooded scarp-slope and a 

 gentle dip-slope, Avhich is sooner or later truncated as it comes within 

 the erosive province of the stream in the valley. This structure 

 has a curious effect on local agriculture, the fertile soil of the dip- 

 slopes being cultivated to the fullest extent right up to the hill- 

 summit. It is certainly striking, after climbing some 800 or 900 

 feet of rough woodland or wild moorland, to come suddenly upon a 



1 One-inch (Old Series) Sheet 56 N.E. 



2 Horizontal Section No. 30 (1853). 



3 ' Stratigraphical Geology ' 2nd ed. p. 174. 



4 ' Siluria ' 4th ed. (1867) p. 134. 5 Ibid. p. 243. 



G Discovered by Garnett-Botfield : see C. Lapworth & W. W. Watts, Proc. 

 Geol. Assoc, vol. xiii (1894) p. 328. 



* H. W. Banks, Q. J. G. S. vol. xii (1856) p. 93. 



s2 



