498 Prof. Sedgwick on the May Hill Sandstone, 



found in 1836*. In a country like South Wales we may rejoice 

 if we can but take one safe step. I then made two complete 

 traverses across the Upper Cambrian groups of South Wales, 

 between the Silurian terrace and the sea, still looking and in- 

 quiring for a trace of the Bala limestone, but in vain. But I 

 did gain what I thought good evidence to prove, that the equi- 

 valent of the Bala limestone, whatever form it now took, was 

 not far from the base of the great undulating scries of South 

 Wales ; and from this opinion I have never swerved. 



To examine the Llandeilo sections of the Towy was not then my 

 object, but I crossed two lines, pointed out to me by Murchison, 

 which seemed to connect the Llandeilo Flag with the base of the 

 Wenlock terrace. This done, I made a hasty traverse through 

 a portion of the South Welsh coalfield, and so ended the labours 

 of one summer, — the hardest I think of my geological life. 



In 1833 I was, during the early summer months, crippled by 

 illness and incapable of taking the field ; but I saw the beautiful 

 Silurian sections which were exhibited before the British Asso- 

 ciation by the author of the ' Silurian System ; ' and I also gave a 

 short summary of my results in Cambria as above described ; 

 and I remarked that our work seemed to be interlaced on the 

 east side of the Berwyns, and that we could not connect our 

 groups together without some joint labour in the field. 



In 1834 we did visit, together, the best Silurian sections from 

 Caermarthenshire to Denbighshire. I believed the sections on 

 what appeared the evidence of demonstration; they were the 

 most clear and striking I had ever beheld ; but I never saw their 

 base, 01* considered their relations as admitting of any doubt. 

 I accepted them as they were offered in the supposed Silurian 

 order of superposition (fig. 5. p. 313). But when we reached 

 the sections on the eastern side of the Berwyns, a country I had 

 previously examined, I became startled at the conclusions which 

 followed. The Meifod and Craig-y-Glyn beds were pronounced 

 to be Caradoc and Llandeilo f. Now if the Meifod beds were 

 Lower Silurian, then the Glyn Ceiriog beds must also be Lower 

 Silurian. But the Bala limestone and calcareous slate were not 

 Lower Silurian, because they underlaid the great Upper Cam- 

 brian series of South Wales, over which, in the Silurian sections, 

 were placed the Lower Silurian rocks. On this point there was, 

 in fact, no difference of opinion ; for, as a conclusion from the 

 Berwyn sections alone, my friend excluded the Bala limestone 



• The visit in 1836 was made for the purpose of comparing the Culm 

 trough of Devon with that of South Wales. When my friend and fellow- 

 labourer had left me, I devoted a few days to the older Cambrian rocks ot 

 Pembrokeshire. 



t See sections of the Silurian System, pi. 32. fig. 9. 



