170 David Milne, Esq., on Polished and Seriated Rocks, 



pouth, and leave marks of that direction on the sides of the wall- 

 faces as they rushed past them. It is only at the north part of the 

 gully that these ruts, deviating from the horizontal, and dipping to 

 the north, occur. 



Some of the scratches, after persevering horizontally for 18 or 20 

 inches, suddenly indicated a bending downwards, and a greater faint- 

 ness of marking, at their eastern extremities. The blocks being press- 

 ed on the wall-faces by the onward current, would, of course, produce 

 ruts corresponding with the line of the current, only so long as there 

 was sufficient pressure on them ; but the pressure could not be exactly 

 continuous for any length of time ; and as it diminished, these blocks 

 would, by their own weight, droop, and thus produce the appear- 

 ances observed. 



But whilst the direction of the rush of waters at Arthur Seat and 

 the neighbourhood, seems to have been from the NW., the appear- 

 ances at Linton indicate a direction from the north or NE.; for a 

 current from the NAV. would not easily have smoothed the rocks 

 there, which are smoothed and striated on their faces fronting the 

 SE. The locality in Fife referred to, would indicate a movement 

 from the NNW. 



Farther, on this point, I may mention, that between Musselburgh 

 and Joppa, one of the boulders bears two sets of scratches, — one set 

 running NNW., and the other W. by S., by compass, the former 

 having been partly obliterated by the latter, and therefore prior to 

 it.* 



This, however, is a very subordinate point, and immaterial to the 

 great question which now agitates geology, whether it is by aqueous 

 or glacial action that the phenomena of smoothed rocks and trans- 

 ported boulders are to be explained. 



Without wishing to deny that, in some situations, glaciers may 

 have produced the effects, I certainly do deny that there is as yet the 

 slightest evidence of their existence in the Lowlands of Scotland, 

 and maintain, that the smoothed and striated rocks of Arthur Seat 

 and Markle Ridge, and the boulders which occupy the clay covering 

 of these rocks, are all to be ascribed to the action of an impetuous 

 torrent of water. 



No glacialist who saw the gully at Sampson's Ribs, or the knolls 

 of Markle Ridge, would venture to say, that a glacier could have 

 existed at either place. There is no valley in which a glacier could 

 bo confined, no mountain to be the birthplace of its flowing ice- 

 streams ; and if a sheet of ice could be supposed to have moved 

 down from Arthur Seat, it would have passed over and across the 

 gully of Sampson's Ribs, and not through it. 



* The boulders which are rutted on their upper surface, must have stuck in 

 the clay, whilst the rest of the debacle moved over and passed them. 



