200 Wilson — Glaciation of Orf or d and Sutton Jits., Quebec. 



rounded rock ridge which constitutes the very summit of the 

 mountain rises about two feet above the surface of the soil 

 cover which lies in the adjacent hollow to the east of it. On 

 the south side of the summit area one of the rounded ridges 

 still shows small rounded hollows on its surface which are the 

 markings Dresser referred to when he wrote of the occurrence 

 of glacial striations on the summit of the mountain. The 



Figure 2. Summit of Orford Mountain, a small rounded dome with gla- 

 cial scorings. 



writer has examined these markings carefully, but could find 

 no evidence to show that these furrows were produced by 

 weathering processes acting on joint planes, as suggested by 

 Chalmers.* Indeed, of all the loose material occurring at the 

 summit, only a very small percentage can be attributed to the 

 local disintegration of the rock in situ. The depth to which 

 the decomposition due to weathering has visibly penetrated 

 the exposed rock surfaces is very slight, except along fracture 

 planes. Microscopically all of the primary minerals are found 

 to be much altered for a considerable depth, bat the rock is 

 not disintegrated. The distribution of the effects of weather- 

 ing is found to be fairly uniform, specimens from the base hav- 

 ing practically the same appearance as those from the summit. 

 On the west side of the summit dome, a few feet from the 



* Ottawa Naturalist, vol. xix, p. 53. 



