OF WISCONSIN AND MINNESOTA. 



153 



greatest extent; the latter varying from a quarter of a mile to a mile in width. On 

 the ridges, besides maple are found elm, birch, balsam-fir, hemlock, and hazel. 



For fourteen or fifteen miles north of the Manidowish, on the meridian line, no 

 rocks but boulders were seen on the surface. On Sections 1 and 2, Township 44, a 

 granite is again in place, possessing the character of that on the Falls of Black 

 River. This is the most northerly outburst of granitic crystalline rocks which was 

 observed on the 4th Principal Meridian. * 



The igneous ranges first show themselves in the bed of the east branch of the 

 Chippewa. This stream was explored by Dr. Litton, who reports his observations 

 on the L'Eau Claire, as follows : 



" Dalles, formed of the sandstones of F. 1, a, commence almost immediately on 

 entering the river, but extend only a few hundred yards. For twelve miles above 

 the mouth, coarse quartzose sandstone is the only rock visible ; this extends, in 

 every case, from the level of the river to the very highest point that I found rock 

 exposed. About fourteen miles above the mouth, the crystalline rocks are in place. 

 They present themselves, on one side or other, at distances varying from two hundred 

 yards to a mile, up to the Falls, which, by the course of the river, are twenty miles 

 from the mouth. At the Falls, the rock is composed chiefly of hornblende, and 

 possesses a crystalline structure ; it is exposed on both sides of the river, but does 

 not rise higher than twenty feet above the water. The general level of the country 

 is about sixty or seventy feet higher. Associated w r ith the hornblende rock, above 

 the Falls, are both gneiss and chlorite slate ; the former in a state of decomposition. 

 These are exposed for seven or eight miles, never rising to a height of more than 

 twenty feet above the river bed, and frequently not more than ten feet, or even 

 less. Everywhere, except on the river bank, these igneous and metamorphic rocks 

 are covered with a drift of sand. 



" Four miles above the Falls, a pink granite was observed, containing large 

 plates of gray mica, and masses of flesh-coloured felspar. Sixteen or seventeen 

 miles above the Falls are Dalles similar to those below the Falls. They are not 

 formed by the crystalline rocks, but by the same coarse-grained sandstone observed 

 below the Falls, which rises to the height of sixty or seventy feet above the level 

 of the river, and extends along the stream some two hundred yards. 



" Twenty-five miles above the Falls, the intrusive rocks are again in place, for at 

 least eight or nine miles, and form a chain across the river, producing a succession 

 of rapids, that obstruct its navigation, known as the Little Falls. 



" Two miles above the Little Falls, and about thirty above the main Falls, pebbly 

 sandstone, of F. 1, a, rests upon decomposed green, gray, and reddish clayey-materials, 

 derived from the decomposition of a rather close-grained granite, destitute of mica, 

 but containing abundance of felspar. 



" So great is the body of sand which overlies the igneous rocks here as elsewhere 



* For a further description of the 4th Principal Meridian, see Colonel Whittlesey's Report. Section 

 No. 2, R, constructed by Mr. Randall, shows the succession of the formations from Lake Superior to the 

 Mississippi, along the line of the 4th Principal Meridian. 



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