David Milne, Esq., on Polished and Striated Rocks » 157 



in its extrcmo length does not exceed 120 yards in length, opens 

 freely at both ends. Indeed, the narrowest part of it, is not at either 

 end, though it is not far from the north end. But in passing from 

 that point where the sides of the trough approach nearest, it gra- 

 dually opens out or increases in horizontal width both ways. Farther, 

 at the north end, the surface of the ground suddenly slopes away, and 

 sinks down from 80 to 100 feet. At its south end, the ground slopes 

 down with still greater rapidity, and presents almost a precipitous 

 face above the level plain, which is about 200 feet below. 



The greatest extent of polished surface is on the east side of the 

 new road, and forms part of the west base of Arthur Seat. There 

 the rocks, for about 80 yards continuously, have evidently been rubbed, 

 and in some places very highly polished. 



On the west side of the new road, there has lately been exposed 

 a surface of rock about 20 feet in length, also very highly polished. 



On this west side, the polished rock extends upwards for about 4^ 

 feet above the road ; it is unknown how far it extends below ; and 

 it would be very interesting to discover. The face of the rock here 

 is exceedingly steep ; in the part close to the road (and therefore 

 nearest to the bottom of the trough) forming an angle with the horizon 

 of 65°, — and about 5 feet above, 47°. 



The debris conceals the upper surface or termination of the rock ; 

 but apparently that side of the trough has been altogether from 15 

 to 20 feet high for some distance along the line of the road. The 

 rock was at most places, on the east side where exposed, almost ver- 

 tical, and at the narrowest part of the gully towards the north, it 

 was almost opposite the pohshed rocks on the west side of the road. 

 Towards the eastward, where apparently the rock is more friable, the 

 poHshed rock does not rise so high above the road, and the polished 

 surface was less steep, and in some places almost horizontal. It 

 there presented the following outline. 



Fig. 1. 



a Boulder-clay. 



h Polished rock surface. 



c Level of New Iload. 



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