ON THE MINNESOTA RIVER. 



487 



White and brown sandstone, similar in character to that found at 

 White Earth Bluff, ...... 



Seam of green siliceous marl, ..... 



Magnesian limestone, containing Lingula and Orbicula, . 



From these measurements it appears that there is a rise of about forty feet in the 

 strata between the last exposure and this point. 



The Blue Earth or Mankato River joins the Minnesota a few hundred yards 

 above this bluff. Our instructions required us to explore this stream and its 

 principal tributaries previous to completing our observations on the Minnesota. 

 "We accordingly began the ascent. 



Half a mile above the mouth, the sandstone, with a capping of Magnesian Lime- 

 stone, appears, forming abrupt cliffs, seventy-two feet high. About one mile above 

 the mouth, the same rocks again occur, in solid ledges, with an elevation of forty to 

 fifty feet. 



About three miles above this locality is the confluence of Lesueur River, which 

 we entered. About half a mile up this stream, an exposure of Lower Sandstone, 

 F. 1, rises to the height of twenty-five feet above the level of the stream, sur- 

 mounted by sixty-eight feet of sand, pebbles, and small boulders, the latter not 

 exhibiting any appearance of stratification. 



A mile further is a similar section, as follows 





Feet. 



1. White and brown sandstone, ..... 



50 



2. Thin beds of loosely cemented conglomerate. 





3. Sandstone, ....... 



5 



4. Thin bed of firmly cemented conglomerate. 





5. Ferruginous sandstone, ..... 



8 



6. Nodules of oxide of iron, and argillaceous iron ore, 



o 



7. Unstratified drift, with large boulders, .... 



18 



The nodules of iron ore have mostly a concentric structure, and appear to be of 

 good quality. The superficial indications render it probable that this bed of iron 

 ore may be both extensive and easily accessible. 



Two or three miles above the mouth, the hills are composed mostly of sand, 

 gravel, and erratics, resting on a thin bed of light, bluish-gray, arenaceous, stratified 

 marl. 



The Psah River comes in on the left side, about five miles above the mouth of 

 the Lesueur River, which, being the larger stream of the two, we turned into it. 

 We had not proceeded far, however, before the water became shallow, and our 

 progress difficult. We succeeded, however, in ascending it some seven or eight 

 miles, by dint of laborious poling and frequent wading, in very rapid water amongst 

 the numerous boulders, but with considerable risk to our craft. At length we 

 reached a region where no rocks could be discovered, even in the lowest cuts of 

 the stream ; and where the whole hills seemed to be composed of confused masses 



* The beds are always given in the sections in the ascending order, No. 1 being the lowest. 



Feet. Inches. 



70 



6 



45 



