igoi] Ells — Ancient Channels. 23 



At most of these the banks are hio^h and the river still 

 apparently follows its original course. At the Roche Capitaine 

 however, and at Des Joachims, secondary channels have been 

 made and the waters diverted. This feature is especially well seen at 

 Desjoachims where the present channel of the river is comparatively 

 new and the course of the old channel lies to the north following the 

 depression occupied by McConnell Lake and coming into the 

 present channel at the head of the Deep River, to the north of the 

 village of Des Joachims in a well defined depression, while the 

 shallow nature of the present channel is indicated by the long line 

 of foaming rapids which come in from the south. The difference 

 in elevation between the foot and the head of these rapids is about 

 forty feet, it is probable that at some time in the histoty of the 

 river, perhaps at the close of the Glacial period, great accumula- 

 tions of sand, gravel and boulders blocked the old channel at a 

 point some three miles above the present foot of the rapids or near 

 the mouth of the Dumoine river, and thus diverted the stream. 

 Possibly the same thing occured at the Roche Capitaine, since 

 here the second channel is seen to the north of the large island in 

 the river, this channel being now largely dry at ordinary stages of 

 the water. 



Indications of this blocking of the old course of the Ottawa is 



seen in the great accumulations of boulders near the village of 



Mattawa, which represent terraces of morainic origin, modified 



by the agency of the waters of the river. This evidently had 



some effect upon the river channel at this place, since Dr. A. E. 



Barlow in his report on the region says that "a well defined old 



river-channel occurs running through the rear portion of the 



village between the main street and the railway station which has 



evidently been followed by the Mattawa or its antecedent stream. 



It leaves the Mattawa about a mile above its mouth and reaches 



the Ottawa at the foot of the rapid nearly three-quarters of a mile 



below"* 



About twenty miles west of Pembroke the river makes 



a sudden bend to the south at what is known as High View. 



Just above this on the north side is a bold headland known as 



Oiseau rock, which rises abruptly from the surface of the stream 



Rep. Geol. Sur. Can. I897 Vol. X, p. 178, Part I. 



