MR MILNE ON THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 289 



during the formation of the whole basin, that these vegetable accumulations 

 took place. Are we to suppose that, at these periods, a more extensive inunda- 

 tion than usual occurred, whereby a larger quantity of vegetable matter was 

 carried off? This would imply a degree of violence, inconsistent with the per- 

 fect integrity of the plants (many of which are very delicate) preserved in the 

 coal-seams. The circumstance that these vegetable debris would be mixed and 

 entangled with sand and mud, whilst, in the actual coal-seams they are free 

 fi'om all such admixture, presents no difficulty, — because they would continue to 

 float long enough to get quit of the soil attached to them. Besides, there might, 

 even after deposition, be a separation of the earthy from the vegetable matter. 

 But, would the quantity of vegetable matter floated down in this way, be suffi- 

 cient, when it sunk to the bottom, to overspread the whole district, — (a district, 

 be it remembered, in one direction fourteen miles in extent), so as thereafter to 

 form one individual seam of coal ? Look, for example, at the North Greens seam. 

 It crops out for eight or ten miles, along the south side of the Pentlands, — and 

 then, at Carlops, it turns round towards the SE., skirting the foot of the Lammer- 

 muir Hills towards the east. We must suppose that every part of the sup- 

 posed estuary was entirely covered with a mass of floating vegetables ; and not 

 only so, but that this mass became gTadually, uniformly, and regularly thinner 

 towards the SW., S., and SE. I confess it is not easy to conceive such a condi- 

 tion of things ; — for, unless it can be assumed that the sea in which this widely 

 extended mass floated, was calm, and free from currents, the continuity of the 

 mass, and its uniformity of thickness, must have been destroyed. 



A good deal, therefore, depends on the extent and character of the aqueous 

 medium in which the coal vegetables were floated, and at the bottom of which 

 they were deposited. If it was a small and shallow lake, the waters of which 

 were still and tranquil, there would be little difficulty in the problem. Or, if it 

 was an arm of the sea, narrow and land-locked, so that its waters could not be 

 agitated by the swell of the ocean or by extensive currents, the difficulties would 

 not be insurmountable. But this could not have been the character and condi- 

 tion of the waters, at the bottom of which the strata of the East-Lothian and Mid- 

 Lothian coal-fields were deposited. We have seen, that whilst towards the west 

 they washed the base of the Pentland Hills,* towards the south they reached the 

 Lammermuir Hills, and stretched alongst their range even as far as Dunglass, 

 (a distance of about thirty miles), and covered the whole of the present counties 

 of East and Mid Lothian. Moreover, into this expanse of waters we see that 



* This is on the supposition that the Pentland Hills had been ejected and formed before the epoch 

 of the coal-measures. If they were ejected afterwards, then the coal-seams must have extended much 

 farther towards the west than they do now. I admit that it is by no means easy to determine whether 

 the Pentland Hills were elevated before or after the deposition of the carboniferous rocks. On this point 

 see some observations in the notes explanatory of the Map in the Appendix. 



VOL. XIV. PART I. 



