MR MILNE ON THE GEOLOGY OF ROXBURGHSHIRE. 



457 



for about a mile, and gives a direction of north 60 west. Its more general direc- 

 tion, indicated on the map, is north 54 west. 



I shall proceed now, however, to give a more particular account of the bear- 

 ing and width of this dyke, at every part of its course where it is visible, stating 

 at the same time the nature of the rocks which it intersects. The importance 

 of these details, if not here self-evident, will be seen in the second part of this 

 memoir. 



Commencing with the south end of the dyke, where it enters the county 

 among the Cheviot hills, I have to mention that its course may be traced down 

 the face of the hill to the Kale Water, which it crosses between Upper and Nether 

 Hindhope. It may be distinctly followed along Eccop Hill, passing not far from 

 the top of it on the north side. Here the Rink quarry (to be afterwards par- 

 ticularly mentioned), situated on the Newcastle and Edinburgh road, where the 

 dyke is worked, and distant from this point about three miles, bears by compass 

 north 55 west. This part of the dyke exhibits on the surface of the muir, huge 

 horizontal columns. Proceeding about two miles west, we find the dyke crossing 

 in that interval several burns, and forming in most instances rocky barriers in 

 their channels. It has been recently quarried on the west side of Edgerstone 

 Burn, which is about half a mile from the Rink, and there the dyke is 36 feet 

 wide, its walls running in a direction north-west by west. 



In the part of its course just described, the dyke traverses first the coal- 

 measures, which here stretch over from Northumberland, and reach nearly as far 

 as Eccop Hill. It then enters the porphyry formation, which continues to the 

 Edgerstone Burn just referred to, where it enters the greywacke formation. 



At the Rink Quarry, the dyke takes several bends, which are well shewn in 

 the extensive workings to which it has there been subjected. The following 

 woodcut will explain these. 



Horizontal Section, shewing course of Basaltic Dyke through Greywacke Strata. 



The course of the dyke is indicated by the letters ABCDE, the distance from 

 A to B being about 100 yards, from B to C 8 yards, from C to D 20 yards, 

 from D to E 6 yards. 



VOL. XV. PART III. 6 H 



