88 THE GEOLOGY OF MINNESOTA. 



[Pope, itso. 



rocks in place being found in its entire length within the territories of the 

 United States. It abounds with boulders or erratic blocks of granite, which 

 in all cases are very much rounded by the action of water. They are most 

 abundant upon the highest ridges of the prairies, and cause all the rapids 

 in the small streams tributary to the Red river, the St. Peter's and Mississ- 

 ippi. About seventy miles north of our frontier (at Pembina) a secondary 

 limestone appears at the falls of the Red river, which is unquestionably the 

 basis of the whole valley, but at what depth below the surface at different 

 points it is impossible to say. There are no rocks in place found west of the 

 Mississippi along the route pursued by the expedition to the Red river of the 

 North, and the geological features of the banks of the Mississippi have been 

 given in the report of Mr. Nicollet, published in the year 1842." 



Capt. Pope states that there were three routes by which to reach the 

 valley of the Red river of the North, used by the traders and trappers in 

 their annual pilgrimages to the Mississippi with their peltries. The most 

 southern follows the valley of the St. Peter's, and descends into the plains 

 of the Red river near lake Traverse. The middle route leaves the Missis- 

 sippi at Sauk Rapids, seventy'six miles above the mouth of the St. Peter's, 

 and intersects the Red river near its most southern point. This is the route 

 pursued by the expedition. The northern route follows for some distance 

 the valley of Crow Wing river, and turning the northern extremity of Otter 

 Tail lake, descends into the valley of the Red river near the mouth of Buffalo 

 river. These routes were mere trails, and followed as far as possible the 

 open prairie. 



The further geographical facts which his report contains can be sum- 

 marized as follows: Between Pembina and the mouth of the Red Lake river 

 he passed successively the Two rivers, Park river, " Riviere au Marais No. 1," 

 from the east; Big Salt river and " Riviere au Marais No. 2," from the west; 

 Turtle river, and "Riviere au Marais No. 3" from the east, and a small 

 stream called " Coulee* de 1'Anglais." The largest of these were the " Riviere 

 au Marais No. 1," and the Park, Big Salt and Turtle rivers, which were 

 about eighteen yards wide and six feet deep, the Red Lake river itself being 

 about fifty yards wide near its mouth and fourteen feet deep, and with a 



Coulee is often anglicized to couley or ctuKe. It signifies a deep ravine, and was in common use nmonu the 

 ek voyageure. 



