and the Palaozoic System of England, ^^ 475 



the banks of the Severn), are described in the Report of the Bri- 

 tish Association (Transactions of the Sections, pp. 58 and 59. 

 1853). The general results derived from these sections are as 

 follows {supra, p. 313. fig. 4) : — 

 Fourth section, 



7. Carboniferous series. 



6. Devonian series. 



5. Ludlow group, in three stages. 



r d. Wenlock limestone. 

 4. Wenlock group, in J c. Wenlock shale. 



four stages. | h. Lower Wenlock or Woolhope limestone. 



[ a. May Hill sandstone and Norbury limestone. 

 3. Caradoc sandstone of Horderley, &c. 



o ci, 1 p cor.' 1. (With. Aqnostuspisiformis, Olenus'i, Asaphus'^i 

 2. Shales, &c. of Shmetonj citheropsisAldensis,Siphomtretamicula,kc. 

 I. Longraynd slates. 



In this section Nos. 2 and 3 are obviously unconformable to 

 the old Longmynd slates. But the base of No. 4 is also (though 

 not so obviously).sunconformable to No. 3. Hence this 4th sec- 

 tion is not a continuous and complete, but is a broken and in- 

 complete, section. It has not therefore been correctly assumed 

 as a typical section ; nor can it, under the name Caradoc sand- 

 stone, be made the foundation of a correct nomenclature *. 



So far I have been dealing, in the way of recapitulation, with 

 the evidence of my preceding paper : and bearing on exactly the 

 same questions, I now proceed to comment on some additional 

 evidence which fell under the notice of Professor M^Coy and 

 myself during our short recent tour made in a portion of South 

 Wales. 



I. New Radnor and Presteign Sections. 



The accompanying sketch does not profess to exhibit an accu- 

 racy of outline or exact proportion among the beds ; but it does, I 



Old Radnor. Fig* !• 





1. Trap. 2'. Limestone dipping S.E. 



2. Limestone dipping N .W. 3. May Hill sandstone. 



3. Wenlock shale. 2". Reappearance of the limestone near Presteign. 



believe, exhibit the right order of the several groups, and there- 

 fore may help to illustrate the following remarks. The lower 

 parts of the valley extending from Presteign to Old Radnor are 



* (See fig. 4. p. 313. supra.) The black line, between Nos. 2 and 3 of 

 this section, is drawn inaccurately. It ought to be parallel to the dividing 

 lines of No. 3 ; for 2 and 3 are perfectly conformable and in an unbroken 

 sequence. 



212 



