MR MILNE ON THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 281 



pregnated. In the centre of the spot will generally be found a filament of iron, 

 derived, as I conceive, from the blanched part of the stone. These white spots 

 are common in this old red sandstone-formation, as well as in the new red sand- 

 stone-formation lying over the coal-measures, and a portion of which occurs in 

 Berwickshire and Roxburghshu-e. But I never saw any in the red sandstones of 

 the coal-measures proper. 



It is hardly necessary to explain, that, in this older formation, there is not 

 the slightest appearance of coal or lime ; and I may add, that, so far as I know, 

 no organic remains have ever been found in these red sandstones. 



The strata of this formation rise to the hUls, and dip under the coal-measures. 

 They are steepest where they are near the hills ; and they seem to lie conformably 

 with the coal-measures. 



From the short outline which has now been given, it is obvious that the coal- 

 measures of this district must have been formed, not only at a subsequent epoch, 

 from that in which the greywacke strata of the Lammermuirs were formed, but 

 under conditions totally different. Every thing leads to the conclusion that these 

 greywacke strata, after their formation and consolidation, had been thrown up 

 by volcanic agency ; and that, after this period, there had been deposited on their 

 flanks, first a series of red sandstones, and next the series of strata commonly 

 termed coal-measures, which have been particularly described in this memoir. It 

 may be proper to observe, that, on the south side of the Lammermuirs (viz. in 

 Berwickshire and Roxburghshire), there is a deposit first of red sandstone, and 

 secondly of coal-measures, possessing exactly the same general features which 

 these formations have on the north side of the range, — so that it is more than 

 probable that these sedimentary strata were formed on both sides of the range of 

 hUls, by the same agents, and under similar, though certainly not exactly the 

 same circumstances. 



What those circumstances were, can best be discovered from an examination 

 of the strata themselves ; for, if properly examined, they will be found to con- 

 tain, to a considerable extent, internal evidence of their origin and history. 



It is hardly necessary to enter upon any formal demonstration of the now 

 generally received opinion, that most if not all the strata composing the old red 

 sandstone and carboniferous formations must have been deposited in an aqueous 

 medium. The beds of conglomerate, skirting the sides of the Lammermuir Hills, 

 composed as they are entirely of greywacke, and occasionally trappean boulders 

 and pebbles, cannot be explained in any other way than by supposing them to 

 have been washed down from the adjoining hills, and to have accumulated along 

 the margin of a sea or lake. In like manner, the sandstone strata which lie over 

 these conglomerates, composed as they are of sand and occasionally fine gravel, 

 necessarily point to a similar condition of things. This inference, obvious from the 



VOL. XIV. PART I. N n 



