501 



as the strisB of the smoothed rock. There is a hollow precisely simi- 

 lar immediately under the summit of Arthur's Seat, to the north, 

 with a ridge of equal length forming its boundary in that direction. 

 This valley and this ridge lie in the same line, namely, pointing 

 toE. 15° N. 



On the north haunch of Arthur's Seat there are many exposed 

 trap surfaces of a rounded form, but much weathered, and sometimes 

 greatly shattered. These may be considered as roches moutonnees in 

 a state of extreme decay. 



I have only to remind the Society of what Mr Maclaren pointed 

 out many years ago, that fragments of the trap of Salisbury Crags 

 are scattered over the back of that hill, and in some instances have 

 been transported across the valley, and placed higher on Arthur's 

 Seat than any part of the parent hill now is. One has settled a little 

 above the hollow just described as existing under the summit of 

 Arthur's Seat. From the very hard greenstone, again, which con- 

 stitutes the south haunch of the. Lion, large blocks are carried east- 

 ward along the slope of the hili to the extremity of the park in that 

 direction. 



It will be observed, that amongst the whole phenomena, old and 

 new, there are some remarkable harmonies. All the drifted matters 

 have been carried eastward. The prominences are all abrupt towards 

 the west, while to the eastward they are tailed away, affording on 

 that side shelter to accumulations of loose matter. The striae in four 

 exposed surfaces of the two hills, and two remarkable troughs or 

 hollows on Arthur's Seat, are coincident in direction, namely, between 

 W. 15° S. and E. 15° N., being precisely the direction in which the 

 striae in numberless other places throughout this district, and all the 

 longitudinally-shaped hills and hollows also, are disposed. Over- 

 looking the somewhat discrepant direction of the hollow over Samson's 

 Ribs, — for which some accidental cause may be speculated on, — this 

 uniformity in the phenomena may be said to speak strongly for the 

 deep ice-current, which I have long upheld as necessarily to be 

 assumed, to account for a large class of appearances in Scotland, as 

 I believe also in Scandinavia and in North America. 



I have already pointed out, however, that ice has operated in more 

 ways than one in our country.* The traces of a later glacial system 



* lleference is made to a paper which I had the honour to read to the Society 

 in December 1852, and which is published in Jameson's Journal for April 1853. 

 VOL. III. - 3 T 



