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 4 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 on the west branch of the Chippewa belong chiefly to F. 1, d, and F. 1, ¢, 
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. 
