BORDERING ON THE WISCONSIN RIVER. 



293 



be considered the head of steamboat navigation on this river. Occasionally, fine 

 sections of sandstone were displayed in the bluffs to-day, rising from thirty to one 

 hundred feet above the water-level. 



A short distance above Sauk Prairie, I noticed, for the first time on this route, 

 the Lower Magnesian Limestone, overlying the sand-rock, which reaches, in the course 

 of the river, from Whitney's Rapids to this place. At the junction of the two 

 rocks, they present a very peculiar banded appearance, when exposed in mural 

 cliffs, owing to the intercalation of thin layers of the two formations, and their wea- 

 thering unequally. 



At this point my geological observations ceased ; the object of the reconnoissance 

 having been to trace the rocks from Lake Superior to their junction with the Pro- 

 tozoic Sandstone of the Mississippi Valley, and make incidental observations on the 

 topography of the country. Having accomplished these objects to the best of my 

 abilities, I hastened toward the rendezvous at Prairie du Chien, where we arrived 

 on the morning of the 19 th October. 



SECTION HI. 



NARRATIVE OF EXPLORATIONS MADE IN 1848, ALONG A PORTION OF THE NORTH SHORE OF LAKE 

 SUPERIOR, AND ON LEFT-HAND, ST. LOUIS, UPPER EMBARRAS, VERMILION, RAINY LAKE, BIO FORK, 

 AND THE NORTHERN MISSISSIPPI RIVERS. 



On the 10th of June, I received, at the mouth of Crow Wing River, your final 

 instructions, regarding my field of operations for the season, and the nature of the 

 reconnoissance to be made along the north shore of Lake Superior. As the geography 

 of the northern portion of the District was but little known, and as the geological 

 exploration of this country would be far in advance of the linear surveys, the Depart- 

 ment had determined to have the position of important points determined, as nearly 

 as might be, by astronomical observations with the sextant and chronometer. This 

 especial duty was assigned to Colonel Charles Whittlesey, the result of whose labours 

 has already been communicated to you. 



We were detained at the mouth of Crow Wing River nearly a week after your 

 departure for Red River of the North, in consequence of our inability to procure 

 canoes and a sufficient number of voyageurs. Our first intention was to ascend the 

 Mississippi to Cass Lake, and proceed thence to Rainy Lake, by way of Red Lake ; 

 and from that point to cross the country to Lake Superior, by way of Vermilion 

 Lake. But, on making an estimate of the length of time which would be required 

 for such a journey, it was obvious that the small lot of provisions we had brought 

 with us would not last beyond Rainy Lake River. As there was little probability 

 of our being able to obtain supplies at either Red Lake or Rainy Lake River (which 

 we subsequently ascertained we could not have done), and none could be procured 

 at Crow Wing, we determined to reverse the projected line of exploration, and pro- 

 ceed immediately to Lake Superior ; and, after having made a reconnoissance of 

 that portion of the north shore of the Lake designated in my instructions, to pro- 



i 



