David Milne, Esq., on Polished and Striated Bocks* 159 



and at these prominences the faces looking north are much smoother 

 than those looking south. 



The direction of the polished wall on the west side of the road is 

 apparently not parallel to that of the rock immediately opposite to 

 it. The rock exactly opposite is not seen, heing probably covered 

 by debris ; but if it were uncovered, it would probably be found 

 running NW. by W., judging from the parts nearest it, whereas 

 the polished rock on the west side runs NNW. 



Having now described the polished and smoothed condition of the 

 rocks, I proceed to describe the furrows and scratches on them. 



(1.) In i\\e first place, they are quite innumerable. They are to 

 be seen on almost every part of the rocks, which have been polished 

 or rubbed. 



(2.) They, of course, vary in length, from a few inches to several 

 feet. One of them I traced continuously for six feet. 



(3.) The direction of them coincides, generally speaking, with 

 that of the gully. When seen on the steep or vertical wall-faces 

 of the rock, they are, in almost all cases, found to be horizontal. 

 But at the places where the polished rock-surface projects beyond the 

 general line, the furrows and scratchings are not horizontal ; some 

 of them slope to the horizon as much as 4°, or even 5°. 



In all the cases of this kind, the sloping lines are on the faces of 

 the rocks which project beyond the average line of the side into the 

 gully. Their dip is to the north. 



There is one rock-face, however, on which the scratches dip, 

 though, apparently, the rock does not project beyond the general 

 line of the side. This is on the west side of the road. Close to 

 this wall-face there exists a large basaltic boulder, which, to a con- 

 siderable extent, has choked up the gully at this point, and, of course, 

 rendered the passage of any body through it more difficult. On the 

 NE. side of the boulder itself, there are some well-marked ruts and 

 scratches. 



(4.) The scratches and ruts vary in depth and width, as much as 

 in length. Generally speaking, the longest are also the widest and 

 deepest. The one before referred to as six feet long, is about one 

 inch wide, and one-third of an inch deep. 



It appeared to me, that the longest and deepest scratches are in 

 the following places, viz., first, on the horizontal rock-surfaces ; and, 

 secondly, on those sloping wall-faces, where the scratches dip to the 

 north. 



Generally, the scratches seem to be the most numerous at a low 

 level ; and on those parts of the rocks facing the SW., which were 

 only a little, if at all, polished, there was only a faint trace of scratch- 

 ing. In one place, viz., at 6 c on the foregoing figure, where the 

 SW. face was rubbed and smoothed, there were two or three scratches 

 visible. 



Having described the polished and striated appearance of the 



