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



At other places, these strata have not been brought up, at least to the very surface. In proof of this 

 last remark, reference might be made to the Garlton Hills (marked on the Map), which I conceive to 

 be contemporaneous with the Pentland and Lammermuir hills, and among which no transition rocks are 

 to be seen. 



No one can traverse the Lammermuir hills, without perceiving that at least one-third of the rocks 

 composing them are felspathic. The latter occur not merely in the form of dykes and veins, of great 

 width and extent, — but also of amorphous masses or hills. St Abb's Head consists of a coarse flesh-co- 

 loured felspar. At Fassney the felspar is associated with quartz and large scales of mica, forming a 

 regular granite. In the burn which flows over the northern brow of Soutra Hill from Laurie's Den 

 to Woodcot, enormous masses of sienite and granite may be seen mixed with the greywacke strata. 

 It is hardly necessary to say, that these strata in the Lammermuir, as in the Pentland range, are gene- 

 rally vertical, and that the direction of the strata is always east and west, or very nearly so, — circum- 

 stances which strongly support the inference suggested by the general direction of the hilly chain, 

 that the force, by whatever agent produced, which was the immediate cause of those felspathic eruptions, 

 acted in lines running nearly east and west. 



The Basalt, Greenstone, and other augitic trap-rocks, are denoted on the Map by a green colour. 

 But it is right to mention, that, besides those so indicated, there are rocks of the same species among 

 the Pentland hills which it was unnecessary, and would have been very difficult, to have separately repre- 

 sented. Among the Pentland hills, as among the Lammermuir range, the greywacke strata occur, and 

 are most frequently nearly vertical. 



Having thus spoken generally of the different formations or sets of rocks represented on the Map, I 

 proceed to offer a few remarks, in detail, with regard to each of these formations. 



(1.) The Carboniferous formation. 



The object I had in view, was to trace individual strata belonging to this formation, through the 

 district as far as they reached, — to lay down on the Map the outcrop of the most important of these 

 strata, — and to mark their variations of thickness. The strata whose outcrop I have laid down on the 

 Map, are merely coal-seams and limestone strata, — and on account of the very reduced scale of the Map, 

 I have been obliged to leave out many of these. The perfect accuracy of all the lines, I will not vouch 

 for ; — though it is proper to observe, that, in the original map, they were laid down from information 

 obtained on the spot, or from plans, with an examination of which I was occasionally favoured. But, 

 however accurately these lines may be mapped, every one must be aware that they must represent very 

 incorrectly the actual facts. Lines drawn on a horizontal plane, never can represent with truth the 

 circumstances which occur on an uneven and undulating surface. From this cause it happens that the 

 distances between the outcrops of the strata, as marked on the Map, particularly along the Roman Camp 

 ridge, cannot be in exact conformity with fact. Still, I believe, that the outcrop of the different seams, as 

 laid down, is in no case very distant from the truth : — where I was uncertain of the line of outcrop, dots 

 have been used instead of a thick line. 



I ought to mention, that there is some uncertainty as to the identity of some of the coal-seams 

 which crop out on the outskirts of the coal-fields, comprehended between the east and south-west points. 

 These belong to the lower members of the basin, which, from being in those parts much reduced in 

 thickness, and consequently little worked and sought after, are not accurately known. It is possible, 

 therefore, that, on future examination, some of those lowest members of the series may have been found 

 to be wrong numbered. 



I may extend these remarks to embrace the limestone strata which lie at the bottom of the basin . 

 There are two or three such strata, and from their proximity to each other, it is very difficult to recog- 

 nise them. That there are two separate strata of limestone along the soutli part of the district, must be 



