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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 5, 



Conclusion. 



Although I know that much hard labour in the field is yet required 

 before any one can lay down accurately the physical relations of the 

 different rocks constituting the Silurian system of the South of Scot- 

 land, or can attempt to delineate in that region the changes in the 

 sedimentary matter in the range of strata of the same age from the 

 E.N.E. to W.S.W., enough has now been presented to the public by 

 my precursors, with what has been now communicated*, to enable 

 us to arrive at some positive conclusions. 



Even if no geologist had carried thither his hammer and compass, 

 the geographical observer and the artist would perceive throughout 

 all the hilly tracts of the southern counties of Scotland, extending 

 from the German Ocean to the Irish Sea, a sameness of outline in 

 the soft and undulating contours of the ground . This outline, we 

 may now fairly infer, is due to frequent bends of the stony frame- 

 work. In examining many years ago, in company with Professor 

 Sedgwick f, the sea-cliffs of St. Abb's Head, between Berwick and 

 Siccar Point, I could not avoid being impressed with the rapid cur- 

 vatures of the greywacke and the bold projections amidst it of masses 

 of porphyry. Nor could I traverse the country from Dunglass to 

 Dunse and not marvel at similar phsenomena, whether the greywacke 

 and schists of the Lammermuir Hills were of purple or grey colours, 

 or their intrusive rocks were porphyries, greenstones, or amygdaloids. 

 In a separate excursion, made last summer before he joined me, Prof. 

 Nicol, on walking over these same hills near the coast, ascertained 

 that, whilst the strike of the strata was persistent, there were no less 

 than five anticlinals in the short space of three miles ! 



These facts, and the distinct proofs I have cited of numerous anti- 

 clinals, curvatures, and fractures in the coast-sections of Ayr and 

 "Wigtonshire on the west, and in Galloway and Kircudbright on the 

 south, give us the key to explain the outline of the whole region. 

 They teach us at the same time, that amidst these convoluted masses, 

 intruded upon as they have been by numerous eruptive rocks, it must 

 be impossible, without long-continued and close labour, to find the 

 band which marks the oldest stratum or true geological axis. Thus, 



separating, as he is disposed to do, the carboniferous limestone series from the 

 Red Sandstone ; for, after indicating a synclinal arrangement of the former in the 

 bed of the Annan, and an anticlinal heave near Kelhead, he shows the forma- 

 tion to be so brought against the red rock, that, although separated by a fault, the 

 latter dips to the south at precisely the same angle as its older neighbour. I do 

 not believe that the British Isles afford a similar example of true new red sand- 

 stone being so related to rocks of the age of the carboniferous limestone. 



* Mr. Cunningham has written memoirs communicated to the Highland Society, 

 &c, which throw light on the dislocations and change of direction in the strata 

 around the granitic and porphyritic tracts of Galloway and Kircudbright. We 

 are also indebted to Mr. D. Sharpe for having put together all tbe later discoveries 

 and observations of the geologists, who have explored Scotland, on a map, which 

 has been very useful at the Geological Society in all recent discussions upon Scot- 

 tish geology. 



f Sir John Hall and Mr. Sheriff Alison were our associates. I much regret 

 having lost my note-book in which the distinguished historian sketched many of 

 the features of the bluff cliffs from the sea beneath them. 



