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unless we had the most conclusive proof of it, would be utterly incredible ; 

 still I believe that they should only be admitted to explain facts which are 

 otherwise insoluble, and that we are often misled by starting with the hypo- 

 thesis of a fault rather than arriving at it as a result of careful induction. Now 

 in the present case I believe it would be an error to suppose that the sudden 

 transition from the Cambrian to the Wenlock, in this locality, was the result 

 of so violent a cause, for this reason, that we find the country at the base of 

 these hills is oovered with the Wenlock formation, and that up to a certain 

 height along them it is unconformably deposited upon their upturned edges. 

 This would argue that, subsequently to the deposition of the Caradoc, this imme- 

 diate neighbourhood was submerged while the Wenlock rocks were forming. It 

 is true that in other places the Wenlock and the Caradoc rocks are seen to be 

 unconformable, but it has been shown that a particular stratum may continue 

 its course of formation during many changes in the level of the pre-existing 

 strata. It is to be particularly noticed that the base of the Longmynd hills, 

 for a considerable extent on both sides, is clothed as it were with the Llan 

 dovery, and in their proper succession the Wenlock rocks, brought in, certainly 

 not by a fault, but by the regular course of deposition. Along the southern 

 extremity of these hills this fact is very striking— the relative position of the 

 two bears all the appearance of an ancient sea beach, suggesting that during the 

 Wenlock period the Longmynd stood up from the surrounding oeean like an 

 island. 



Now the conclusion arrived at by Sir R. Murohison is that during the 

 chief part of what is called the Bala or Caradoc epoch there was no material 

 interruption in the succession of the strata, but that a period of disturbance 

 took place at its close, when the Llandovery commenced. Tbis would coincide 

 with what is observed here. It is, moreover, evident that as a rule the forma- 

 tion of a stratum takes place during the subsidence of the earth's surface. 

 Layer after layer is formed and covered up by the detritus oarried down by 

 streams from the land. If, then, after the Bala formation over the surrounding 

 ocean bed had taken place*, this locality began to subside, we might naturally 

 expect to find what is actually found, a shore-like deposit of rounded pebbles 

 and sand along the higher ground, and farther out, in deep water, a more even 

 and finer shale. 



And this leads me to say a word on the conglomerates of the Longmynd, 

 or rather those of the surrounding system of hills. A remarkable succession of 

 these of different ages can be traced running parallel with their axis. To mention 

 the chief— one of very marked character— extends along the eastern flank of 

 the Caradoc for several miles. It can be traced from Cound, near Salop, in the 

 north, and as far south as Corston, in tie parish of Clunbury. At Frodesley it 

 rises into a considerable bill, and also at Horderly forms the crest of a ridge. 

 It is of much importance in correlating or determining the relative position of 

 the strata in which it occurs. Higher in the series, though more intimately 

 associated with the Longmynd, is the Llandovery conglomerate, to which I 



