MR MILNE ON THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 277 



harder, larger grained, and more crystalline, shows itself SW. of Coats-farm, and 

 appears to run into the Garlton hills ; for it is again seen at a point SE. of Coats, 

 and about a mile from the former spot. 



A third dyke makes its appearance at Cockenzie, and may be traced east- 

 wards running under Port-Seaton, and for a little distance along the shore. There 

 it is lost ; and as in the case of the Morison's-haven dyke, another greenstone dyke 

 takes on about 400 yards to the north. This second one runs by Boglehill, and 

 then by Harelaw, and so on to Redhouse Castle, beyond which I have not traced 

 it. The circumstances just referred to, suggest the notion that a dislocation of 

 the dyke had, at some period, taken place, and that they had then been separated. 

 But I merely throw this out for farther inquiry. The Cockenzie part of the dyke 

 runs E. and W., and at its west end measures about 76 feet across. The Bogle- 

 hill part of the dyke runs E.SE., and gets thinner towards the E. At Boglehill, 

 it is between 50 and 60 feet wide ; at Gordon-Spittle it is only 30 feet wide. 



A greenstone dyke may be seen crossing the Water of Leith, a few yards to 

 the east of St Bernard's Well, and running in a direction N.NW. It is only a few 

 feet wide. 



A greenstone dyke, probably connected with the one last mentioned, runs to 

 the north of Craigentinny House, by Lochend, Quarryholes, Hillside, Marshall's 

 Entry (Leith Walk), and Albany Street. It was worked formerly at all these 

 places — and, as I am informed, was seen at the east end of Abercromby Place, in 

 excavating for the foundations of the houses. It is between 50 and 60 feet wide. 

 It runs in a direction N. 14° W., or very nearly in that of the one last mentioned. 

 It seems to get thinner towards the west. 



III. POINTS OF CONNECTION BETWEEN STRATIFIED AND UNSTRATIFIED EOCKS. 



Having thus described generally the Stratified and the Unstratified Rocks as 

 separate and distinct classes, it may be proper next to notice some circumstances 

 which characterize them when they are in contact. 



(1.) I need hardly, in the present advanced state of geological science, ad- 

 duce any facts to shew the alteration in quality or internal structure of the stra- 

 tified rocks, where they come in contact with trap. It is enough to say, that all 

 the well known phenomena — of the coal having much of its bituminous qualities 

 expelled, — of the sandstone, shale, and other strata being hardened, &c., when in 

 contact with the trap-dykes, occur in the district. These effects were most par- 

 ticularly observed along the Niddry dyke. 



(2.) There is one phenomenon, however, which is said to be common else- 

 where in such circumstances, but which I have not observed, and which I rather 

 think does not occur here at all. It is said that strata, when intersected by trap- 

 dykes, are very much altered in their relative position ; and that, as in the case of 



