GEOLOGY OF THE PHILIPSBURG REGION OF QUEBEC 321 



of Ai. It is likely that as a general rule the compressive forces 

 effected folding in the grey facies, and fracture in the buff facies. 

 The most southerly extension of the "high rocks" exposure on the 

 shore south of the boundary exposes well the buff facies of Ai. 

 There is a sKght valley between these cliffs and those of the grey 

 facies to the north. Although the bedding in the buff facies in 

 most places is almost impossible to determine, the impression given 

 is that they stand almost vertically. If this is the case and if the 

 buff facies really overlies the grey, the buff beds have been faulted 

 down and upturned in the general deformation which closely folded 

 the underlying grey strata. 



About 250 yards east from the lake at the international boundary 

 the yellowish white, brown weathering magnesian limestones of the 

 buff facies come in on top of the grey. In one place one-eighth 

 mile south of the boundary, this line of contact was traced in a 

 continuous outcrop for 100 yards. At the southern extremity 

 of this outcrop the yellow white limestone appeared to be standing 

 on end, in very much the same attitude that it appears to be stand- 

 ing in the escarpment three-fourths of a mile south of the boundary 

 on the lake shore. In this place it would seem that the yellow white 

 limestone is above and younger than the grey limestone. Following 

 the boundary east to the valley parallel to the lake which is occupied 

 by the Philipsburg-Highgate Springs road, the limestone of the 

 grey and buff facies seems to become interbedded and finally grades 

 into a pure compact dove grey limestone. The outcrops of these 

 beds are conspicuous because they weather smooth and very often 

 Kght grey to white. These beds belong to Logan's A2. Beds of Ai 

 and A2 can be followed from the Boundary northeast by almost 

 uninterrupted exposures to Morgan's Corners. Here a well defined 

 line of fault is beautifully shown north of the road running east 

 to Bedford. 



A3 follows A2 first with reddish grey granular beds of limestone 

 and these in turn by black Kmestone. In an unpublished letter, 

 Dr. G. A. Young, of the Geological Survey of Canada, has recognized 

 these two quite distinct phases of Logan's A3. He named these 

 members A3 a and A^b. Since the integrity of these divisions is 

 maintained in the faulted zone at Morgan's Corners, it is important 



