THE GEOLOGICAL STRUCTUEE OF SOUTH CORITWALL. 269 



The instances of alleged unconformabilities throughout the 

 paper are very numerous, and, did they really occur but to 

 one half their number, their existence would not say much for 

 the care and power of observation of men like De la Beche 

 and Sedgwick, both very able geologists, noted for their correct- 

 ness, especially the former, who surveyed the county and whose 

 opportunities were great. 



While fully admitting the ability of Mr. Collins as a geo- 

 logical observer, and agreeing with him in the removal of the 

 term Devonian as applied to much of the strata and the sub- 

 stitution of Lower Silurian in its stead, I cannot but think that 

 he has fallen into errors which only tend to complicate and 

 involve the geology of the district 



With regard to my own observations on the age and order 

 of succession of the strata of the area under consideration, I 

 wiK be very brief, laying before you only an outline, as this 

 subject alone would be much more than sufficient for a separate 

 communication. 



Let me begin by drawing your attention to the small strip 

 of strata at Veryan Bay, coloured on the geological survey maps 

 as Lower Silurian, as I conceive this to be the key to the geol- 

 ogy of the surrounding district. 



These beds were first examined and found to be f ossilif erous 

 by Mr. Peach, and subsequently by.Murchison and Sedgwick, 

 who, from the decided and well marked character of their 

 included organic remains were able to refer them to the Caradoc, 

 a member of the Lower Silurian. 



The whole of the adjoining strata were still regarded as of 

 Devonian age, and even at the present time are mapped as such 

 in the most recent survey maps. 



As already stated, Sedgwick, in order to explain the anom- 

 alous position of a member of the Lower Silurian resting upon 

 the Devonian, had recourse to the theory of an inversion of the 

 strata. Had he extended his survey of the adjoining strata he 

 would have found that there was a natural sequence without 

 any sign of disturbance of the underlying rocks passing uj) into 

 the Oaradoc, and that in the beds beneath them Devonian fossils 

 were not to be found in that region. 



