the Neighbourhood of Kelso. 1 51 



It is also frequently lamellar — a fact which would have little 

 weight, as pyrogenous rocks occasionally assume this structure, 

 but that the arrangement and thickness of the lamellae, are pre- 

 cisely the same as in parts of the neighbouring sandstone. When 

 on the point of taking my final departure from the hill, I met a 

 mass of porphyry, so remarkable in its characters, that it banish- 

 ed all doubt as to the correctness of my opinion. The surface 

 of this mass presented stripes, alternately of a deep and light red 

 colour, which, while they preserved their relative thickness and 

 parallelism, were bent and twisted, just as we so often see the 

 lamellae of gneiss and mica-slate. The regularity with which 

 the plates of different colours preserve their relative thickness 

 throughout the stone, its striking resemblance to the striped 

 sandstone of the district, and the difficulty of accounting for its 

 characters, unless we consider it a portion of this sandstone, soft- 

 ened and altered by heat, are sufficient to prove that my opinion 

 is well founded. As this singular block of porphyry lay on the 

 side of the hill, I have no proof that it ever formed a part of it ; 

 but its characters leave no doubt that it belongs to the same for- 

 mation, which is found, I believe, along the whole of Tweed- 

 dale, forming insulated, often conical, hills; and supposing that 

 it has travelled from some of these, it proves that at no great 

 distance, the resemblance between the porphyry and sandstone 

 is still stronger than at the Black Hill. I was obliged to leave 

 Kelso immediately after my second visit to this interesting spot, 

 and, as it is probable that I shall never revisit the lovely banks 

 of the Tweed, I trust that my observations may attract the atten- 

 tion of some experienced geologist, and lead to further inquiry. 

 Such investigations derive additional interest from their con- 

 nexion with some abstruse and disputed questions in geology. 

 In no district can satisfactory results be more confidently ex- 

 pected than in Tweeddale, on account of the simplicity of its 

 structure, and the frequency with which the rocks are well ex- 

 posed. I shall conclude by observing, that wherever I have 

 used the word felspar, excepting in one or two instances, it is to 

 be considered the soda-felspar, for which there are now at least 

 four names. As labradorite is its most beautiful, and, in some 

 respects, most characteristic, form, if it were distinguished by 



