MR MILNE ON THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 33I 



the strata are there covered by the boulder clay. The strata dip at an angle of 

 about 60° to the E.SE. On the west side of the quarry is a stratum of shale, 

 which runs along the whole length of the quarry for several hundred yards. 

 This stratum, along its edge or outcrop where it is in contact with the clay, is for 

 a considerable distance raised up from its natural slope of 60°, to almost a vertical 

 position. There is a line of crack visible, occasioned by its having been bent or 

 forced into that position ; — which crack runs parallel with the edge or crop of the 

 stratum, and is distant from it several feet. That the shale has been pushed east- 

 wards into this position by the superincumbent boulder-clay, I think there can be 

 no doubt. 



The remarks now offered correspond entirely with the inferences of a very 

 distinguished member of this Society, the late Sir James Hall. He it was who 

 first pointed out the phenomena in this neighbourhood, and particularly to the 

 west of Edinburgh, of what has been termed " crag and tail." He discovered 

 various ruts and scratches on different parts of Corstorphine Hill ; and ascertained 

 their average direction to be W.SW. by compass. It was his opinion, that the body 

 of water which flowed over Corstorphine Hill, carrying with it the enormous 

 boulders which were left on its east side, could not have been much less than 

 1000 feet deep. 



My own observations in other parts of the district, quite confirm Sir James 

 Hall's opinion. I have shewn that the boulder-clay, with its imbedded blocks, 

 reaches in several places to the height of 960 feet above the present sea. It 

 cannot be imagined, that the water which transported these blocks did not 

 reach a higher level. On the contrary, the water must have been very deep, in 

 order to have possessed the force necessary to transport materials so weighty and 

 so extensive. If therefore, we find these materials reaching to a height of 960 

 feet, the water which transported them must have been at least 1700 feet above 

 the sea, — a depth sufiicient to have covered most of the Pentland and Lammer- 

 muir hills. 



It is not difficult to understand, where the imbedded blocks of stone may 

 have come from. But it may form a question, where the enormous mass of clay 

 could have come from. That it was derived from the westward, is rendered pro- 

 bable from the fact of the boulders imbedded in it having been brought from the 

 westward. But farther than this, I do not think we can yet safely go in quest of 

 the true explanation. I have several times heard a member of this Society, pos- 

 sessed of great practical knowledge, express opinions on this subject, in which, 

 however, I cannot concur. He thinks that the immense volume of boulder clay, or 

 " old alluvial cover," as he has termed it, may be accounted for by the slips which 

 have broken up the subjacent coal-measures. No doubt there must have been, 

 as just explained, an immense mass of debris occasioned by these slips. But 

 these materials never could have produced the houlder-day of the district. They 



