448 MR MILNE ON THE GEOLOGY OF ROXBURGHSHIRE. 



4. The formation or class of rocks just mentioned, I mean the Nero Red Sand- 

 stones, there are some reasons, though they are not, in my opinion, conclusive, for 

 supposing to exist in Roxburghshire. 



At one time the whole of the red rocks of Roxburghshire were assigned to 

 this class, and the opinion is still entertained by some geologists ; nor is it alto- 

 gether devoid of plausible arguments. 



(1.) In the first place, that the new red sandstone formation exists on the 

 western borders of the county can scarcely admit of doubt. It extends from the 

 plain of Carlisle, up the Esk as far as Canonby, and also up the Liddell to about 

 200 yards below Penton Linns, and a little way up Archerbeck Burn. At Penton 

 Linns, the division betwixt the coal-measures and the upper red rocks is very pal- 

 pable ; the former being there nearly vertical, and the latter abutting against them, 

 and partly covering them, but dipping westward at an angle of 30. As the for- 

 mation thus reaches into Liddesdale, it was not unnatural to suppose that the same 

 formation existed, likewise, on the eastern borders of the county. It is well known, 

 however, to geologists, that the appearance of this formation in the plain of Car- 

 lisle, is owing to an enormous sinking of the strata, which took place in that part 

 of England ; and, accordingly, its eastern boundary is marked by a fault, which 

 divides it from the carboniferous rocks of Northumberland. This fault shews 

 itself on the Liddell, about 200 yards below Penton Linns, where the new sand- 

 stone rocks are seen with their edges tilted up against the limestones and other 

 beds of the Canonby coal-field, and in such a way as very clearly to indicate that 

 there has been a general sinking of the newer formation. 



(2.) In the second place, there is a very remarkable horizontality in the red 

 rocks of Roxburghshire, which seems to indicate a comparatively recent period 

 for their deposition. And this circumstance becomes the more striking, when it 

 is found that, on the other hand, there are many localities bordering on this dis- 

 trict of country, where the coal-measures are inclined at considerable angles. Thus, 

 at Bedrule Hill, where, as has just been shewn, the limestones, shales, and yellow 

 sandstones are vertical, the red sandstones immediately adjoining in Huntly 

 Dell, are perfectly horizontal, and indicate no signs of disturbance. Generally 

 speaking, it cannot be doubted that the red rocks present fewer deviations from 

 the horizontal, than the coal-measures. Must they not, then, have been deposited 

 at a subsequent period ? 



(3.) Farther, it appears that, in several parts of Liddesdale, red rocks have 

 actually been seen lying above coal-shales and sandstones. 



These are some of the grounds on which it has been or may be maintained, 

 that the new red sandstone formation prevails in Roxburghshire. Nor am I in- 

 clined to deny, that possibly some rocks more recent than the coal-formation 

 may exist. That the Old Red formation exists, is clear from the discovery, in 

 various places, of the fossil fish characteristic of that formation, and from other 

 facts already alluded to. That the Coal-Measures also exist, is equally certain ; 



