in the Neighbourhood of Edinburgh. 237 



Lastly, during the tremulous efforts by which lines of fracture 

 have been made to approximate, igneous matter has not unfre- 

 quently intruded itself through these fissures. Thus we may 

 conceive a large fissure through which trap has protruded, to 

 be indicated by the eruptions, continued with little interrup- 

 tion, which we trace from Tinto to the Pentlands, and thence 

 to Salisbury Craigs, in a direction of nearly S. W. to N. E. 



From these observations it would appear, that the carbonife- 

 rous strata under our consideration shew striking marks of the up- 

 heavings and the rents which they have undergone both before 

 and subsequent to the completion of their deposit, accompanied 

 with eruptions through them of plutonic rocks. In conse- 

 quence of these rents, and of the uplifting power which has been 

 exerted along the line of them, the coal-fields of Mid-Lothian 

 have been broken up into various systems of strata, severally dif- 

 fering from each other in the extent of the beds which have been 

 made to emerge. This difference would naturally be in confor- 

 mity with the circumstances under which the uplifting force has 

 exerted its influence. 



In examples where the anticlinal energy has acted powerfully 

 at one and the same time upon a great extent of surface, we find 

 that at the line of rent or fissure very deep-seated beds have been 

 made to emerge, or crop out : — as may be shewn on the coast of 

 North Berwick and among the Pentlands, by the emergence of 

 beds even inferior to the carboniferous group. But examples are 

 far more numerous of the line of fracture being distinguished by 

 the cropping out of no deeper seated beds than those of a ma- 

 rine limestone, to which I have given a middle place in the car- 

 boniferous system to which the limestone of Burdiehouse belongs. 



The systems of strata, separated from each other by lines of 

 fissure which are in greater or less contiguity with the limestone 

 of Burdiehouse, I shall now explain in reference to the following 

 section. 



