part 8] SlLUBtAX ROCKS Of THE CLt'X-FOBEST D1STBICT. 



241 



In addition to demonstrating the uninterrupted transition from 

 Upper Silurian through Downton ian rocks, one of the principal 

 results of this investigation is the establishment of a succession in 

 these strata of the Welsh Borderland identical with that determined 

 by Miss Elles & Miss Slater for the Ludlow district of Shropshire. 



Another feature of interest in the district is the increased 

 thickness of all the Upper Ludlow rocks. A comparison of the 

 thicknesses of the strata in the few districts which have been 

 described in detail according to the new classification may be shown 

 in tabular form : — 





Mocktree 



Bucknell. ,- ., , 

 (o miles east 



of Bucknell). 



Ludloiv l 



(11 miles 



east). 



South 

 Stafs 2 

 (37 miles 

 E.N.E.). 



Temeside Shales 



Downton Sandstone ... 

 Chonetes Beds 



feet. feet. 

 350 120 



110 about 40 



350 160 



300 120 



? 300 150 



— 250 



feet. 

 110 



about 50 



150 



11Q 



40 



75 



feet inches. 

 33 6 



79 6 



[23 6 



11 6 



Rhynchonella Beds 



Dayia Beds 



Aymeslry Limestone ... 





1410 840 



535 148 



It is not easy to compare the thicknesses in other districts, owing 

 to the varied groupings of the strata which have been adopted. 

 The following may be considered approximately correct : — 



1 



-,-, 7 77 Malvern and Ledbvru 



Bucknell. , 00 ., ., .^ 



(32 miles south-east). 



Torttvorth ' 

 (50 miles 

 S.S.E.). 



Temeside Shales 



feet. feet. 

 350 .400 3 



110 10-100 4 



350 -) 



300 [• 100-200 b 



? 300 ) 



— 10-40 ? 6 



feet. 

 



p 

 I 40 



1 

 Downton Sandstone 



Chonetes Beds 



Rhynchonella Beds.. 



Dat/ia Beds 



Aymestry Limestone 



1410 520-740 





1 G. L. Elles & I. L. Slater, Q. J.G.S vol. lxii (1906) p. 199. 



2 W. W. King & W. J. Lewis, Geol. Mag. dec. 5, vol ix (1912) pp. 437 et seqq. 



3 G. H. Piper, Trans. VYoolhope Nat. P.C. 1895-97, pp. 310-13. This is assuming 

 that the Ledbury Beds and the Temeside Shales are homotaxial, which, from the 

 descriptions of the former, seems very probable. 



4 J. Phillips, Mem. Geol. Surv. vol. ii, pt. 1 (1848) p. 99; see also T. T. Groom, 

 ' Geology in the Field ' Jubilee vol. Geol. Assoc. (1910) p. 709. 



5 J. Phillips, op. cit. p. 94, 



6 T. T. Groom, op. cit. p. 709. 

 ' J. Phillips, op. cit. p. 192. 



