part 3] SILURIAN ROCKS of the clun-forest district. 221 



9. The Highest Silurian Rocks of (lie Clun-Forest District 

 (Shropshire). By Laurence Dudley Stamp, B.Sc. 

 (London), A.K.C.L., F.G.S. (Head January 9th, 1918.) 



[Plates XIX & XX.] 



Contents. 



Page 

 I. Introduction 221 



II. Topography and Surface- Geology 223 



III. Classification and Description of the Strata 225 



IV. Description of some Typical Sections 236 



V. Tectonics 239 



VI. Summary and Conclusions 240 



I. Introduction. 



In the counties of Radnorshire, Montgomeryshire, Shropshire, and 

 Herefordshire, rocks of Ludlow age have been indicated over 

 considerable areas on the Geological Survey maps. 1 There are also 

 several large outliers of Old lied Sandstone strata in this region, and 

 both sets of rocks are crossed from Church Stretton on the north 

 to beyond Fresteign on the south by the great Church- Stretton 

 Fault (see fig. 1, p. 222). This fault marks approximately the 

 boundary - between the shelly calcareous type of Silurian sediment 

 in Shropshire and the argillaceous type in Wales. The Shropshire 

 succession of Ludlow rocks has been studied in detail (most recently 

 by Miss G-. L. Elles & Miss I. L. Slater 2 ), and the ground has been 

 well known to geologists since the original work of Murchison. 3 

 On the other hand, the country immediately to the west of the 

 great fault is little known, and no detailed account of the upper- 

 most Silurian and Old Red Sandstone rocks has been published. 

 Scattered references certainly exist, but they deal with the general 

 characters of the district rather than with special features and 

 definite localities. 



It was, therefore, suggested by Dr. A. H. Cox that I should 

 undertake an examination of the area, with the view of determining 

 the sequence and distribution of the uppermost Silurian strata. 

 These rocks are here of especial interest, since the district occupies 

 an intermediate position between the Shropshire (Ludlow) district 

 with its calcareous t} r pe of sediment, on the one side, and the Welsh 

 area, where the corresponding rocks are of an argillaceous character, 

 on the other. 



1 One-inch (Old Series) Sheet 56 ; also Sheets 50, 61, & 55. 



2 Q. J. G. S. vol. lxii (1 906) p. 195. 



3 ' Silurian System' vol. i (1839) pp. 195 d seqq.; 'Siluria' 4th ed. (1867) 

 pp. 123 et seqq. 



Q. J. G. S. No. 295. g 



