24 NEW YORK STATE MUSEUM 



part of the slope of the mountain was wave washed during the 

 late marine invasion of the Champlain valley. I could not 

 determine that the delta surface immediately north of this 

 locality exhibited a trace of dislocation attributable to the post- 

 glacial origin and continuation of this supposed fault into the 

 rocks underlying the delta. 



Probable fault on Mt St John, Quebec. Mt St John is the 

 small conical elevation of basic igneous rock seen standing up 

 on the plains between northern Vermont and the St Lawrence 

 river. Viewed from the train on the Intercolonial Railway 

 between Chamblj' and Beloeil, St John presents an outline on 

 its northern aspect like that shown in the appended sketch, 

 figure 6. On ascending the mountain as high as the quarries 



Fig. 6 Outline of Mt St John (Monnoir) viewed from the north. The lower part of the 

 iketch is meant to show the tc?p of the forest. 



worked on its eastern face near the summit, it is found that the 

 steps shown in the above view are separated from the slope 

 back of them by evidences of fracture, and in one case, I believe, 

 also of dislocation. The most pronounced fissure which I exam- 

 ined at the level of the highest quarry showed a gap partly filled 

 with large blocks which had tumbled in from the sides and the 

 slope of the mountain above the bench. The fissure opens at 

 the surface much above the level to which, according to my 

 determinations, the sea extended in the postglacial marine inva- 

 sion ; moreover, the chasm is not of the wave-made type. When 

 the sea makes a chasm it removes in so doing the blocks of rock 

 in and about it or above the level of the chasm floor. The 

 annexed sketch, which below the surface line is partly conjec- 

 tural, gives at least the superficial aspects of the locality as I 

 saw them. 



