ON THE MINNESOTA RIVER. 



493 



of artificial basins, which greatly enhance the beauty of the country, especially 

 when skirted, as they sometimes are, by groves of trees, and frequented by a 

 variety of water-fowl, which tend to animate and relieve the otherwise almost 

 deathlike silence which so often pervades the prairie. 



For about fifty miles above its confluence with the Mississippi, the St. Peter's 

 has a sluggish current, and is slightly turbid, — hence the Dakota name of Minne- 

 sota] i. 



For several months in each year there is sufficient depth of water for steamboats 

 of small draught to ascend as far as the Little Rapids, usually estimated by the 

 voyageurs to be fifty-six miles above the mouth. This impediment could probably 

 be overcome by a single lock of five to six feet. The present keel-boats of the Fur 

 Company are (excepting during high water) unloaded again at this point, and 

 reloaded again above the rapids, after which they meet with no further obstruction 

 for a distance of sixty miles, to Traverse des Sioux, which is as far as the St. 

 Peter's is used for the transportation of freight. Beyond this point the goods 

 for the Indian trade are conveyed in carts. 



There is abundant evidence of the rise of land throughout the valley of the St. 

 Peter's ; and I would call attention to the fact that the ancient elevated bed abounds 

 in boulders, while but few are seen in the upland prairie, and none on the recent 

 alluvial deposits. Hence I infer that the second bench was not formed by the 

 same causes which accumulated the first bench. 



I would observe here that many of the water-courses represented on Nicollet's 

 Map as rivers, are really very small streams, with not sufficient water to render 

 them suitable even for canoe navigation ; they are in fact mere creeks or rivulets. 



On the St. Peter's River and its tributaries, the Lower Sandstone, F. 1, and 

 Lower Magnesian Limestone, F. 2, are the prevailing rocks for a distance of two 

 hundred and seventy to two hundred and eighty miles southwest of the Mis- 

 sissippi. 



The last exposure of the Lower Magnesian Limestone on the St. Peter's is about 

 half a mile above the mouth of the Mankato, or Blue Earth River, where it has 

 only a thickness of twenty-seven feet. The underlying sandstone is still seen 

 extending some thirty miles beyond, viz., nearly to the mouth of the Waraju 

 River ; but one mile higher up, there are altered red sandstones, quartzite, and 

 conglomerate, which can be traced to the first exposure of granitic rocks on the 

 St. Peter's. 



These are no doubt the lower beds of F. 1, more or less changed in their appear- 

 ance by metamorphism where they abut upon the igneous rocks, some of the beds 

 assuming the character of a close-grained, compact sandstone, and quartzite, varying 

 from a light to a deep brick-red colour, in fact, presenting the usual lithological 

 character of the beds associated with the red pipestones, so highly esteemed by the 

 Indians, and found in the same geological position in other parts of the District. 

 The last exposure of the magnesian limestone on the Mankato, is about six miles 

 south of the St. Peter's, where it is sixteen feet thick. 



The underlying sandstone can be traced six miles beyond, in a southerly direction, 

 to one mile above the mouth of the Wantonwan River, where it is seen just above 

 the water's edge. 



