318 E. M. KINDLE RECONNAISSANCE OF PORCUPINE VALLEY 



bell river. Folds ranging from a few hundred j^ards to perhaps a mile 

 in width occur in this region. 



Two anticlinal uplifts of the larger type occur in the region. One of 

 these is coextensive in. width with the Lower Eamparts; the other in- 

 cludes the beds exposed for about 7 or 8 miles below the International] 

 boundary. A large number of observations in dip and strike were made' 

 near New Eampart House, just above the boundary. In 90 per cent of 

 these the strikes ranged between north 25 degrees west and north 45 

 degrees west. In every case the dips observed were westerly. Westerly 

 dips continue down the river for 7 miles, ranging from 20 to 60 degrees, 

 but averaging perhaps 35 degrees. The northwesterly strike prevailing 

 at the boundary sometimes swings to northeasterly. These westerly 

 dips appear to belong to the western limb of an anticline having its 

 axis east of the boundary a short distance. The reconnaissance was not 

 continued far enough beyond the boundary to ascertain its position. The 

 beds elevated to the surface by this uplift include a large proportion of 

 quartzites. These offer greater resistance to weathering than the surface 

 Paleozoic beds to the westward, which are largely shales and limestones. 

 The north and south mountain belt near the boundary is consequently the 

 result of the anticlinal structure just described, which has brought the 

 ■quartzites within reach of the sculpturing agencies of erosion. 



The second anticlinal uplift of the larger type includes the limestones 

 exposed in the Lower Eamparts. A belt of Silurian and Ordovician 

 limestones 14 miles in width trends north and south across the Porcupine 

 at the Lower Eamparts. They are flanked on both sides by rocks of 

 younger age. The normal dips which should characterize broad, simple 

 anticlinal folds have been complicated by faults, two of which have been 

 recognized, while there are doubtless others which have not been recog- 

 nized. 



Applying the name of the shallow gorge through which the river crosses 

 this fold, it may be called the Lower Eampart anticline. This fold finds 

 topographic expression in a series of low ranges of mountains and hills 

 trending north and south. 



FAULTS 



The most extensive fault which has been recognized crosses the river 

 immediately below the western entrance to the Lower Eamparts. The 

 plane of this fault has not been seen, but it has been recognized through 

 the discordance in the succession of the faunas and its position is known 

 within about 100 yards. 



On the north bank of the river, at the entrance to the Lower Eamparts, 



