154 



FORMATIONS OF THE INTERIOR 



on the L'Eau Claire, that the soil can derive little fertilizing chemical principles 

 from the intrusive rocks ; it is generally but little better than that of the sandy 

 region of the Chippewa, above and below the mouth of the Menomonie. 



" From all that was observed of the geological features of the country on the L'Eau 

 Claire, there is little probability of its affording productive ores. The only metallic 

 mineral noticed, associated with the crystalline rocks, on this river, was yellow sul- 

 phuret of iron, disseminated through the hornblende rock." 



Dr. Litton, who also explored the Menomonie, did not observe, on this western 

 branch of the Chippewa, any crystalline rocks in place on the surface, in any part of 

 its course, as far as he ascended it, viz., to the forks of the two small branches 

 which proceed from a series of lakes forming its head waters. There is, however, 

 reason to believe, from observations on the streams east of it, that they cannot 

 be far beneath the surface here, especially as Mr. Randall found, at the pipestone 

 locality, fifteen to twenty miles east of the Menomonie, beds partially metamor- 

 phosed, such as we have usually found lying in close proximity to the crystalline 

 formations. 



Dr. Litton also ascended Prairie a la Crosse River, fifty miles above its mouth, 

 by the course of the stream, and Mountain Island River, ninety to a hundred miles ; 

 and Mr. Macy explored Buffalo River for about forty miles. On none of these 

 streams were any intrusive rocks found in place.* 



On the main branch of the Chippewa, the first crystalline rocks which were 

 observed on the surface were just above the Dalles, about ninety miles by the course 

 of the river from its mouth. 



On the east side of the Chippewa, about twenty to thirty feet above the bed of 

 the river, and a short distance below Allen's Mills, is a deposit of the earthy brown 

 oxide of iron, which appears to be extensive. It is of a variety that would be easily 

 wrought in the furnace. 



The quartzose granite, at the Falls, immediately above, contains but little mica. 

 On the northwest side of the river, a considerable portion of flesh-coloured felspar 

 enters into its composition, and is disseminated in veins ; its structure is rather sub- 

 cuboidal. On the southeast side the felspar is lighter coloured, and the rock of 

 the character of gneiss, whilst other parts of it look almost like a metamorphic 

 sandstone. In consequence of the great flood which occurred just at the time we 

 were there, I had not an opportunity of examining the rock to advantage, since 

 very little of it was exposed above high water. The wood-cut on page 147, repre- 

 senting the Falls of the Chippewa during the flood of June, 1847, shows the 

 exposure of the crystalline rocks as they appeared at that time. 



Near the head of the portage above Ganethie's trading-post, at the mouth of Cut 

 Rock, solid ledges of sandstone, F. 1, a, are again in place, on the west side of the 



* The strata which prevail ou the west branch of the Chippewa belong chiefly to F. 1, d, and F. 1, e, 

 i. e., to the Lingula sandstones and Trilobite grit, treated of in Chapter I. On Mountain Island, Prairie a 

 la Crosse, and Buffalo Rivers, the same beds form, together with F. 1, c, the principal parts of the hills, 

 capped sometimes with F. 2. 



