MR MILNE ON THE GEOLOGY OF ROXBURGHSHIRE. 



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AB are the greywacke strata, having the dyke CDE interposed between them. 

 In some places the dyke is contracted in width. It does not rise to the top of the 

 conglomerate, and it narrows as it rises. A vein of quartz, chlorite, and some 

 other minerals, runs down the centre of it, which is common enough in trap 

 dykes, and is supposed to have been formed in the process of cooling. 



In the Dinlee Burn, one of the tributaries of Hermitage Water, there is a 

 similar felspathic dyke, about 15 feet wide, rising out of the greywacke, and cut- 

 ting across the superincumbent red sandstones. It runs, however, in a north- 

 north-west direction. The strike of the greywacke there, is east-by-north and 

 west-by-south. 



The dyke at Winshielknow, already referred to, belongs to this epoch of fel- 

 spathic eruptions. 



About a mile below Galashiels, there is a dyke of yellow felspar, which runs 

 east and west, following the strike of the greywacke. 



At the foot of Easter Burncleuch, there is also a dyke, about 3 feet wide, 

 running in a north-north-west direction.* In a quarry of greywacke west of Ga- 

 lashiels, on the turnpike road, a dyke of porphyritic claystone, about 13 inches 

 wide, may be seen running east and west. Mr KEMP of Galashiels also informs 

 me that a porphyritic-dike. about 100 yards wide, runs from the Eildon Hills 

 to the hill south-east of Gledswood House. I have noticed a mass of porphyry 

 in the river about half a mile south of Old Melrose. 



In the Allan Water, about half a mile above Fairy Dean, there are two ver- 



* These two dykes I have not myself seen. 

 out for the DUKE of BUCCLEUCH, dated 181G. 

 VOL. XV. PART HI. 



They are noticed in a report by Mr FAREY made 



