David Milne, Esq., on Polished and Seriated Bocks. 171 



4. There is another question, connected with this subject, of the 

 deepest interest in geology, viz., At what level did the sea stand, 

 when the rush of waters which brought the boulder clay, took place 

 and suioothc-d the rocks ? 



The answer to this question would open up another field of in- 

 quiry, too wide to be entered on in this paper, though it is a subject 

 closely connected with the results to which we have been brought. 

 The facts recorded in this paper, are probably too scanty to furnish 

 a satisfactory answer. But, they do go pretty far to shew, that 

 when. the boulder clay was deposited, the sea stood at a level much 

 higher than Sampson's Ribs. In the Memoir on the Lothian Coal- 

 fields before alluded to, it is attempted to be shewn, that it stood 

 greatly above the top of Arthur Seat. 



The horizontal beds of sand and gravel, and of the sloping but 

 stratified bed of coarse gravel, on the SE. side of Arthur Seat, in- 

 dicate very clearly the existence of a sea which stood more than 

 400 feet above the present level ; — though it is difficult to say, 

 whether these beds were deposited before or after the arrival of the 

 Boulder clay. 



Farther, it is probable, that since these deposits took place, there 

 has been no material change in the relative levels of the country. 

 "What is the surface of the present dry land, was then the bottom of 

 the sea, consisting of the very same hills and hollows, plains and 

 slopes, as are now covered with terrestrial vegetation. On this 

 principle, and apparently on no other, is it possible to explain the 

 rounding and smoothing of the existing hills and knolls, on their 

 north and north-west sides ; the bed of coarse gravel at Windygowl, 

 which has the same slope as the surface of the hill ; and the identity 

 of the boulder clay at the top and bottom of Sampson's Bibs. 



After the tumultuous waters which transported the Boulder-clay 

 were assuaged, the upper parts of that deposit were acted on by the 

 natural currents and tides of the ocean ; and in all the hollows, ac- 

 cumulations of stratified mud took place, destined, after the land rose 

 out of the sea, to be the sites of brick and tile works. In this way 

 the boulder clay would everywhere be abraded to a considerable depth; 

 and, hence, there is generally found on its upper surface, great quan- 

 tities of boulders of all sizes. 



I refrain in this paper, which was intended merely to describe and 

 account for a particular phenomenon, from entering farther on these 

 large and difficult questions. But, I cannot conclude, without ex- 

 pressing the gratitude which I feel, in common with every geologist, 

 to Mr Nixon, the inspector of works in the Queen's Park, under the 

 direction of the Commissioners of Woods and Forests, for agreeing 

 to protect and preserve from injury, some of the polished and striated 

 rocks at Sampson's Bibs. They were in the way of the new carriage- 

 drive which Mr Nixon had lined out, and were intended to have been 

 entirely removed. But I had simply to request the preservation of 



