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



slips, the strata are " cast down" on one side of the dyke, or " cast up" on the 

 other. This, however, is not the case with the three principal dykes above men- 

 tioned intersecting the coal-seams, viz. the Niddry dyke, the Morison's-haven 

 dyke, the Cockenzie dyke. 



The Niddry dyke, as already explained, runs for about two miles, and is in one 

 part 60 feet thick. It produces no derangement of level in the strata. But it is 

 important to observe, that, at Brunstain, where this dyke thins away to nothing, 

 and at which point a slip or fissm-e runs towards the east as if in continuation of 

 the dyke, the strata are deranged. They are down on the north side, or up on 

 the south side, 15 fathoms. The strata, though they are neither cast up or thrown 

 down at this dyke, suffer a change in their direction. It will be seen from the 

 map that they, along the line of the dyke, form an angle with each other, the 

 inner sides of which face the west. 



The Morison's-haven dyke was bored through in 1836 by the late Mr Grieve, 

 lessee of Preston colliery. He told me that, on working the coal up to the north 

 side of the dyke, and driving an adit through it, he found the same seam of coal 

 immediately opposite, shewing that there had been no derangement. 



The only reason I have for beheving that the same holds true with the 

 Cockenzie dyke is, that Sinclair, in his Hydrostatics, makes the following state- 

 ment in regard to it : " In the Earl of Winton's ground at Cockeny, there is 

 found a course of coals and freestone, dipping to the SE. in the Links ; and upon 

 the fuU sea-mark, there is a tract or course of wliin-rocks, lying E. and W., under- 

 neath which these coals and stones come through, without alteration of course, 

 and are found within the sea-mark, with the same dip and rise upon the north 

 side they had upon the south side of the said rocks. 



The whin rocks within sea-mark which Sinclair alludes to, must be the 

 Cockenzie dyke, and which he states does not alter the course or the dip of the 

 coals. 



I here conclude the First Part of my Memoir. In doing so, I leave entirely 

 unhandled, and even untouched, many subjects which might have fallen within 

 a geological description of the district, had I aimed at describing every thing pos- 

 sessing geological interest. I have, for example, taken scarcely any notice of 

 the ironstone existing in the district, and alternating with the coals. I have 

 omitted all notice of the vast, though partly explored, field of organic remains. 

 My reasons for not attempting to describe these and other topics of interest, are 

 chiefly two. (1) Because, to have treated of every subject with any degree of 

 accuracy, would have been to compose a work, and not a memoir for this Society ; 

 and (2), Because the matters to which I have applied my attention are of them- 

 selves so important as to deserve a separate description, and are, moreover, so 

 difficult of ascertainment, that they require to be investigated by one who does 

 not allow himself to be distracted by other objects. 



